TECHNICAL REPORT STANDARD TITLE PAG.E 

1. Report No. '2. Government Accession No. 3. Recipient's Catalog No. 

FAA-AM-7 4- 3 

4. Title and Subtitle 5. Report Date 

ADAPTATION TO VESTIBULAR DISORIENTATION. XII. March 1974 

HABITUATION OF VESTIBULAR RESPONSES: AN OVERVIEW 6. Performing Organization Code 

7. Author( s) B. Performing Organization Report No. 

William E. Collins, Ph.D. 

9, Performing Organization Name and Address 10. Work Unit No. 

FAA Civil Aeromedical Institute 

P. 0. Box 25082 11. Contract or Grant No. 

Oklahoma City, Oklahoma 73125 

13. Type of Report and Period Covered 

12. Sponsoring Agency Name and Addres• 

Office of Aviation Medicine 

Federal Aviation Administration 

OAM Report 

800 Independence Avenue, s .w. 14. Sponsoring Agency Code 

Washington, D. c. 20591 

15. Supplementary Notes 

This research was conducted under Tasks No. AM-A-73-PSY-33 and AM-D-74-PSY-33. 

16. Abstract 

Vestibular and visual mechanisms are critical sensing systems in spatial orientation and in spatial disorientation. In aviation or space environments in particular 

the role of the vestibular system is central to the problems of spatial disorientation and "pilot's vertigo. II A question of significant concern in this regard has 

been centered around the possibility of abolishing or reducing undesired vestibular 

responses (inaccurate experiences of motion and eye movements which could blur 

vis ion) by repeated exposure to appropriate stimulus conditions • The present 

report reviews research conducted on this question. The review is generally 

restricted to activity and responses from the semicircular canals of the vestibular 

system. Methodological problems are presented briefly and the influence of arousal 

on vestibular responses is detailed. Data obtained from animals and from man are 

treated separately. At least for man, the term "habituation" may be better defined 

by a dynamic ehange in the form of vestibular responses than by a simple response 

reduction. 

17. Key Words 18. Distribution Statement 

Habituation Availability is unlimited. Document may be 

Vestibular Function released to the National Technical In formaSpatial Orientation tion Service, Springfield, Virginia 22151, 

for sale to the public. 

19. Security Classif. (of this 'report) 20. Security Classif. (of-this page) 21· No. of Pages 22. Price 

Unclassified Unclassified 37 $3.00 

Form DOT F 1700.7 <s-ssl 
or undulating movements of the eyes. Such 

spontaneous responses do not occur with eyes 

open in total darkness.92 Under the open-eyes 

condition in darkness, a large-amplitude nystagmic eye-movement signal is obtained by 

corneo-retinal potential techniques. However, 

subjects rapidly become unaware of the position 

of their eyes and it is possible that they may 

even close their eyes without realizing it. Further, dark adaptation has been shown to influence 

the corneo-retinal potential,75 76 the method most 

frequently used to record nystagmus, and the 

fidelity of tracings obtained by this technique is 

not always true. 31 All in all, there are problems 

associated with any of the methods used; therefore, the method must be kept in mind when 

considering reports of results. Further, in evaluating changes in the nystagmic reaction, the 

measure used may be of considerable significance. 

Although duration of nystagmus has been traditionally the most commonly used means of assessing vestibular reactivity, particularly in cli~ical 

situations, it is also probably the least indicative 

of changes. A thorough assessment requires 

some combination of measures of slow-phase eye 

displacement, velocity of eye movement, frequency of nystagmic beats, and duration of the 

response. 

III. The Problem of Arousal. 

A. Animals. Fearing and Mowrer85 examined 

the effects of anesthesia on habituation of rotation-induced head nystagmus in pigeons. They 

reported no habituation for anesthetized animals 

and a clear reduction in nystagmus for undrugged birds. From incidental observations 

made during the study, Mowrer167 became probably the first investigator to attempt to manipulate arousal factors and examine their influence 

on vestibular responses. "\Vorking with pigeons, 

Mowrer167 differentiated between "excited" and 

"unexcited" conditions, depending upon how the 

birds were prepared for rotation trials, and reported longer durations of nystagmus for the 

"excited" condition. His interpretation, based 

also on previous studies, was that "excitement" influenced the vestibular reaction but that it could 

not account for all of the reduction produced by 

repeated stimulation. Similarly, "\Vendt201 202 

. noted that immobilized animals might go into 

sleep-like states ("animal hypnosis") and that 

2 

various types of stimuli (e.g., auditory or tactual) could restore alertness and reinstate an 

apparently suppressed nystagmus. Hood and 

Pfaltz140 like Mowrer167 reported temporary increases in frequency of nystagmus from rabbits 

when they appeared excited, and, further, noted 

that injections of adrenalin in rabbits which had 

shown substantial response declines to repeated 

rotation produced a partial recovery of nystagmus. Similar r'esults were obtained by Hernandez-Peon and Brust-Carmona134 with acoustic 

startle and by Crampton and Schwam70 who used 

intermittent electric shock and auditory signals 

as excitatory stimuli during repeated rotation of 

cats. 

Drugs haye also been used to affect alertness. 

Crampton68 introduced the use of d-amphetamine 

in an effort to maintain arousal levels in the cat; 

recorded amplitude of nystagmus was increased 

but the usual rapid reduction of nystagmus occurred with repeated rotation. Dowd78 reported 

an increase in recorded amplitude but no change 

in phase relationships of nystagmus during 

sinusoidal acceleration of cats treated with damphetamine; sodium pentobarbital depressed 

the response. On the other hand, Cenacchi, 

Fenu, and Gabrielli34 reported decreased nystagmus from rabbits with various amounts of 

amphetamine. 

W olfe207 has noted that the dosage levels of 

d-amphetamine that have been used to maintain 

animal alertness may have some undesirable side 

effects; some animals become ataxic and appear 

to have vestibulo-cerebellar impairment. In addition, the influence of the drug on eye-movement 

calibrations has been neglected. The importance 

of the latter was noted by Jongkees and Philipszoon 144 145 who reported enhancement of rabbit 

nystagmus with hyoscine and also a slight increase in the (corn eo-retinal potential) eyecalibration signal. Other drugs such as chlorpromazine and cinnarzine, which have a soporific 

effect, have been shown to reduce rabbit nystagmus19 144 145 without altering the eye-calioration 

signal.1H 145 

B. 111 an. Although a number of early investigatorse.g., 3 10 106 m 189 had noted effects on vestibular responses of "indifference," "nervousness," 

or "arousal," "\Vendt202 was apparently the first 

to attempt a definition of "excitement" or 

"arousal" in terms of conditions basic to the state 
of the subject, and to relate these to the problem 

of habituation. He cited two factors in habituation: in one case, repeated rotatory stimulation 

under conditions that provided opportunities for 

visual fixation would result in an increasing 

dominance of the visual stimuli and thereby inhibit nystagmus; in the other case, under conditions of darkness, an "inward orientation of 

attention" would account for nystagmus reduction while an "environment-directed orientation" 

would restore nystagmus or prevent its decline. 

Based primarily on ·wendt's202 notions regarding mental or attentional states, Collins, Crampton, and Posner54 evaluated several instructional 

procedures aimed at controlling alertness during 

rotational stimulation of human subjects (tested 

with eyes open in total darkness) and demonstrated that both quantity and quality of nystagmic output could be manipulated in the same 

subject by instructions regarding mental activity. 

If subjects were asked to relax, daydream, and 

pursue no particular line of thought ("reverie"), 

relatively weak nystagmic responses were recorded; vigorous nystagmus was obtained when 

the same subjects performed continuous mental 

arithmetic (successive division) or signalled 

turning sensations in 90° intervals. c. f., 12 109 

Several other_ studies120 150 156 reported that mental tasks or increased alertness would produce a 

regular nystagmus in place of dysrhythmic responses (see Figure 1), or would prevent apparent adaptation from occurring. 55 123 

The results of subsequent research39 40 43 45 6o 

pointed to the fact that inward- vs. outwarddirected orientations probably do not account for 

the influence of the instructions on nystagmic 

output since both "reverie" and mental arithmetic may be classified as "inward-directed." 

STIMULUS: BILATERAL IRRIGATION FOR 15 SEC 

FIGURE 1. The effeet on caloric nystagmus of alerting a subject. The vertical bar indicates the end of the irrigation; the arrow denotes the point at which the subject (eyes open in darlmess) was told to alert himself. The 

tracing comprises 42 seconds of recording. 

What appears to be of importance is that the 

subject be in a sufficiently aroused or active 

mental state, whether the arousal arises from attending to his sensations, pursuing a particular 

line of thought, performing mental calculations, 

or responding to auditory or other stimuli. It 

should be noted that not all instructions are 

effective in this regard. Some tasks, such as 

counting, may not produce any noticeable effect 

on nystagmus/52 while others, such as tasks involving timing behavior, appear to require relatively little attention with repetitioii. 39 A point 

of additional interest made by Collins, Crampton, and Posner54 was that EEG alpha activity 

was not blocked as a result of angular accelerations nor did it appear to be affected by different 

instructions regarding alertness, although nystagmus was markedly influenced by the latter. 

These EEG-nystagmus findings were confirmed 

in a later study60 which concluded that, at least 

under some conditions, EEG monitoring might 

be a less sensitive indicator of states of alertness 

than are vestibularly-induced eye movements. 

Pendleton and Paine176 made a similar observa3 

tion with newborn infants, and Lidvall152 noted c 

stable alpha activity and lack of blocking during 

caloric vestibular stimulation. More recently, 

Goto, Tokumasu,. and Cohen100 concluded that 

(excluding barbiturates or deep sleep) "the frequency and velocity of rapid eye movements are 

among the most sensitive indices of alertness of 

any, including the EEG." 

That assigned tasks or instructions regarding 

mental activity are important in maintaining 

vigorous nystagmus or restoring a deteriorated 

response has been confirmed in a number of 

studies. e.g .. n 11 24 79 99 147 1ss 192 196 198 Instructions 

have been effective with caloric irrigations,40 45 57 

with drugs/6 59 with alcohol,190 191 with positional 

alcohol nystagmus,129 and when used in conjunction with hypnosis7 although, in one report,142 

hypnotized subjects showed suppressed nystagmus (and, frequently, slow pendular eye movements) in spite of assigned tasks. Under some 

laboratory conditions, mental tasks appeared 

effective in reducing or preventing motion sickness occasioned by unusual vestibular stimulation.64 65 114 Further, the absence of alertness or 
SUBJECT 7 DECElERATION 

SESSION I- REVERIE 

TRIAl I -1-------~~~--,, .... r-._~,·1'-----~----~---~J --------.. -~--r---/·~--- J 

TRIAl2 

-1-----------·----------- ----- -~--- ..... -I -~- ------ --~------- ---- -- .-.r--__,_ I 

TRIAl 3 

-L------~---------------------· l·-- -------------------- ----~-- I 

TRIAl 4 

.~ t . -~-----------¥ ---

SESSION m-MENTAl ARITHMETIC 

TRIAl I 

~;,,~-.J'-_J··-!'-i -... J'-f·I·I· ,. ,j·,(--.J '-.I .,1.: -~·- J --~J'---.~- -J'-i',;''-/'v'--.. .. i'--. .,_i-,_, _ _.,_~'--.. '-·-- I 

TRIAL 2 

--~·,J"'--1'---J'·.r---..f'-J _ {"' -Jv-./ /· r r • ··+ -./'--.,J..._r--.J·--r~"-~---..---I------.~----:----''--.t---.- -...._-._ I 

TRIAl 3 , .. _ ,_ r- ,, 1 ~ f\. (\,._ f·- , . r (\ "' r r- I, J , ,f"-.t--.._1'-J'-.__ ~ "---'----- --..__ .. __ ------ • ....., '--./"' ' '-/ '-1 " ' --!' --~'I 'I 'J f '.J'· '•fV'-1'-,j' .. J'·J',J • -- . ~ ---...,..._;-·- --- ... 

TRIAL 4 

.r-.--I'--...r--~-./'V'----.I'J·· j (1'---...j-J-------..r--v•, j v'~...,~'-/'-,~'-J''-''----.. "--...'~-----

FIGURE 2. The inftuence of instructions on vestibular nystagmus (see text). Vertical bars through the tracings 

demarcate a 15-second period of angular stimulation at 4.5° ;sec'. :\larkers at the end of each tracing indicate 

20° eye calibrations. Recordings were obtained from the subject with eyes open in total darkness. Sessions 

were held on separate days; trials were consecutive on a given day. The "reverie" task was given. during the 

subject's first exposure to laboratory vestibular stimulation. (Reprinted with permission from the Joornal ot 

Experimental Psychology.'") 

arousal, whatever its neuro-psychophysiological 

cause, is probably a major factor in vestibular 

findings which indicate substantial or total suppression of nystagmic responses in schizophrenic 

patients. e.g., 2 37 38 181 Patients who show these 

sub-normal vestibular reactions are frequently 

characterized as apathetic, indifferent, lacking in 

initiative, and showing a poverty of mental content. More recent work with autistic children 

has shown a similar depression of nystagmus.181 

However, the latter deficit has been attributed to 

vestibular dysfunctio~ in a scheme which assigns 

to the vestibular system the role o£ regulating 

the mutual interaction o£ sensory input and 

motor output during the waking state and in 

REM sleep.113 

It is sometimes suggested that the use o£ mental tasks to maintain arousal level represents an 

artificial means of preventing or interfering with 

4 

the habituation process. That is, in the absence 

of structured mental activity, an overall suppression of nystagmus rapidly appears. It is quite 

apparent that a decline of nystagmus can occur 

with relatively few stimulus repetitions in total 

darkness when subjects are uninstructed regarding arousal. It is equally apparent that any 

inadvertent alerting of such subjects will result 

in the reappearance of a vigorous nystagmus.120 

However, since "reverie" assignments can result 

in almost no nystagmus to an otherwise adequate 

rotational stimulus during the first exposure to 

laboratory angular accelerations,39 it would seem 

proper to differentiate between situational or 

perhaps psychological habituation as opposed to 

habituation o£ the vestibular system per se. If 

interest centers around true changes in vestibular 

functioning as a result of repeated testing, it 

would appear to be an experimental prerequisite 
to attempt to effect some control over the mental 

state of the subject. This is particularly true 

when subjects are repeatedly tested in total darkness or with their eyes closed; the tendency to 

doze under such conditions is probably very 

strong. 

IV. Survey of Studies of Animals. 

A. Nystagmus: Rotation-Indwed. Abels1 apparently began experimental evaluation of the 

habituation of head after-nystagmus in pigeons. 

Using a cage suspended from cords which were 

twisted and then allowed to unwind, Abels observed the intensity of the jerks of nystagmus 

following an abrupt stop of the rotation under 

conditions either permitting or excluding vision. 

He noted a marked habituation with repetition 

under the former condition, and a considerable 

but lesser response reduction under the latter 

condition. Abels1 reported that the reduction 

was directionally specific; after repeated rotation 

in one direction, a reversal of direction would 

elicit a vigorous response. 

The reductio;n of head after-nystagmus from 

pigeons tested in the light was confirmed by 

King146 and by Huddleston.141 Huddle~ton141 

indicated that the decline was more rapid for 

squabs than for older pigeons and noted that 

head after-nystagmus could be completely inhibited by visual stimuli in combination with 

voluntary movements of the head. Further, although birds rotated in the dark showed a compensatory head movement upon which nystagmus 

of relatively low amplitude was superim'posed, 

birds rotated in the light showed little compensatory positioning of the head and a relatively 

higher amplitude of nystagmus. 

King146 confirmed Abel's1 finding of the lesser 

reduction of nystagmus with vision excluded by 

testing blind birds, while Fearing,82 rotating 

hooded pigeons alternately clockwise and counterclockwise, reported significant reductions in 

frequency and duration of head after-nystagmus 

with no apparent effect of one direction of stimulation upon the other (i.e., the responses for 

each direction appeared to decline independently). In later studies, Fearing83 84 massed the 

habituation trials ( 61 stimulations in a single 

session) for one group of birds and spaced the 

habituation trials (10 trials per day for 14 successive days) for other birds; the animals were 

5 

then subdivided into smaller groups, each retested at a different interval ranging from two 

to 32 weeks. The data led FearingB4 to conclude 

that spacing the habituation trials led to .greater 

retention of habituation than did massmg the 

trials in a single session. Brown26 confirmed 

this effect with ocular nystagmus from cats. 

King's146 study also introduced a finding. whi?h 

has yet to be experimentally resolved, I.e., m 

tests following habituation stimuli, the number 

of nystagmic head movements declined .more 

when the pigeons' heads were fixed (restramed) 

during the habituation series than when .t~ey 

were free to move in the horizontal plane (VISion 

permitted in all cases). Lumpkin,105 r?tatin~ a 

single rabbit in the light in an extensive senes 

of tests (142 days), used a head-holder for most 

of the trials but tested the animal with its head 

free on specific occasions. He found considerable 

differences in the frequency and duration of 

ocular nystagmus for the two conditions (althouO'h both showed habituation) and concluded 

that "'head-fixed and head-free habituation were 

not the same. Earlier, Maxwell, Burke, and 

Reston160 claimed that ocular nystagmus was reduced more in the light when rabbits' heads were 

free as opposed to fixed. However, they simply 

noted the results of the habituation series for 

their animals (i.e., there was no pre- to post-test 

comparison of the groups under the same conditions) and, initially, the head-free group had 

durations which were approximately 30% shorter 

and frequencies of nystagmus which were about 

50% less than the head-fixed group. 

Mowrer's168 study of the influence of vision on 

habituation of head nystagmus in pigeons also 

contained differences related to head-free stimulus conditions. Mowrer168 reported that pigeons 

tested in darkness showed little or no habituation 

of the duratioJ:i of after-nystagmus followfng a 

large number of rotations with heads free in 

illumination, and a clear (directionally specific) 

decline when the heads were fixed and the room 

was illuminated during the habituation series. 

Similarly, when vision was permitted and a 

striped drum forming a wall around the turntable was rotated with the turntable during the 

habituation series (thereby preventing optokinetic nystagmus), only a slight bidirectional 

reduction of head after-nystagmus was obtained 

during post-tests in darkness (use of the stripeddrum also produced very little after-nystagmus 
during light trials and repeated stimulation resulted in abolition of the response). However, 

when the habituation series was in darkness, bidirectional nystagmic reductions were obtained 

for both the head-fixed and head-free conditions 

although, contrary to results reported by King146 

for tests in which vision was always permitted, 

response attenuation was greater for the latter 

condition. The complete lack of a decline of 

nystagmus in the dark following repeated headfree stimulation in the light and a directionally 

specific decline in the dark following head-fixed 

stimulation in the light are difficult to explain 

since Mowrer168 employed approximately equal 

rates of acceleration and deceleration during the 

habituation trials. However, the experiment was 

a complex one since it involved: fixed vs. free 

head conditions; ocular nystagmus with and 

without head nystagmus; optokinetic nystagmus 

enhancing vestibular nystagmus in one direction, 

and opposing it in th,e other; compensatory head 

positioning allowed to occur with free heads and 

prevented with fixed heads ; and the possibility 

that head position varied among the conditions. 

Mowrer169 later examined the effects of interacting vestibular and optokinetic stimulation with 

pigeons. He indicated that, when vision was 

permitted during and after rotation, afternystagmus was inhibited by : ( 1) the tendency to 

fixate visually on some object, (2) the tendency 

for an optokinetic response to persist after cessation of rotation, and ( 3) the tendency for 

optokinetic head movements during rotation to 

stimulate the semicircular canals in a way which 

counteracted the vestibular stimulus occasioned 

by a deceleration. 

King146 had also reported that decerebrate 

pigeons with heads fixed in the light showed less 

habituation than did normal birds. Halstead127 

and Halstead, Yacorzynski, and Fearing,128 using 

hooded pigeons, found a significantly greater 

decline in duration of head after-nystagmus from 

normal birds than from those with cerebellar 

lesions. Another group of normal birds received 

a similar series of rotations and demonstrated 

the same response reduction; half of the birds 

were then subjected to cerebellar operations. 

Two weeks later, birds with cerebellar lesions 

showed significant recovery of nystagmus; those 

which had not been operated on showed no 

change from the habituated level. Similar findings were obtained from yet another group with 

6 

a 4-week interval. In both control and cerebellar 

birds, some habituation was still present after a 

3-month interval. Moreover, substantial (control 

birds) to complete (birds with lesions) "transfer 

of habituation" was obtained to rotation in the 

opposite direction. The latter result confirmed 

the findings of Mowrer168 although "transfer" 

may be an inappropriate term since the acceleration stimulus used during habituation trials almost surely was of high magnitude and brief 

duration. 

The question of "transfer of habituation" to 

the opposite direction of turning as cited by 

Halstead127 and by Abels1 involves some confuPRE 

POST 

PRE 

POST 

PRE 

POST 

PRE 

POST 

PRACTICED DIRECTION 

~~ 

UNPRACTICED DIRECTION 

DOG NO. II •o•L 

2Sec 

PRACTICED DIRECTION 

UNPRACTICED DIRECTION 

CAT NO. 120 •o·L 

2Sec 

FIGURE 3. Directional specificity of habituation of ocular nystagmus in a cat and a dog. A series of 15 

CW angular accelerations (decelerations were subthreshold) was administered between the pre- and 

post-tests. A directionally specific reduction is evident. The animals were rotated under head and 

body restraint in total darkness.•'··"' Vertical bars 

demarcate the stimulus period; optokineticallyderived calibration markers indicate 40° eye excursions. Similar effects are obtained from other animals. (Reprinted with permission from Acta Otolaryngologica. "') 
swn regarding stimulation (compare Figures 3 

and 4). Early investigators sometimes overlooked the fact that a rotating subject brought 

to an abrupt stop actually received vestibular 

stimulation in both directions (in one direction 

during acceleration, and in the opposite direction 

during deceleration). In Abel's1 situation, the 

acceleration rate was probably of lower magnit~de than that of the deceleration (brake stops) ; 

w1th Halstead,127 the rates were probably approximately equal. In examining only deceleration responses, and in reversing the direction of 

turning after an habituation series, one would 

expect an equally reduced response if the rates of 

acceleration and deceleration during habituation 

had been approximately equal (see Figure 4) or, 

if the rate of the latter were higher, the "unhabituated" direction might be expected to yield 

a. relatively stronger response than that finally 

evidenced in the "habituated" direction. Data 

from the two studies support these expectations, 

and the expectations themselves are based on 

studies by Griffith105 with white rats and by 

Maxwell, Burke, and Reston160 with rabbits, 

which showed a considerable reduction in frequency and duration of ocular nystagmus following repeated abrupt stops of rotation. 'Vhen 

the stopping was then attempted from a faster 

rate of motion, a more vigorous and longerlasting nystagmus was elicited (however, even 

this response was less than that obtained from 

an identical stimulus prior to the habituation 

trials). 

Most of the investigations cited above have 

examined habituation of head after-nystagmus. 

Before beginning a more thorough look at the 

habituation of ocular nystagmus, one further 

study might best be considered here. Fukuda, 

Hinoki, and Tokita96 rotated unrestrained, blindfolded leghorns on perches. During accelerations, these birds showed the usual head deviation 

opposite to the direction of turn followed by an 

appropriate head nystagmus. Upon stopping, 

the head deviation and nystagmus were in the 

opposite direction. In tests following repeated 

exposure to rotation in both directions, the birds 

still showed a head deviation opposite to the 

direction of. acceleration, but now nystagmus was 

very brief; moreover, this attenuated nystagmus 

was followed by a deviation of the head in the 

direction of the turn. The head remained in 

this position until rotation ended; the head then 

'l 

TIIIAL CAT NO. 124 

15 ~'""""""-''-V"-..I'-.J'-.1'-.f'...J'J"'-"-"·l._f'--~ 

~~--v-v---~~~~------~~~·o·l_ 2Sic 

CAT NO. 149 

CAT NO, 150 

Ill -+---~--~ -------~----~ ---------f------_ -_ -------~ -_• _'_' 

ao•L zsec 

FIGuRE 4, Equal rates of repeated accelerations and 

delecerations produce equal reductions in both dinections of nystagmus (cat no. 130). Responses 

need not be permitted to run their course in order 

for the reductions to occur; cat no. 149 received 15 

accelerations which were followed within 0.6 seconds 

by decelerations (arrows). Cat no. 124 shows the 

usual reduction in all phases of the nystagmus response as a result of 15 unidirectional stimulations ; 

strong secondary nystagmus is also evident during 

the first trial. Vertical bars demarcate the stimulus 

periods; dots in the lower tracings indicate approximately 80 seconds of recording not shown. 41 

deviated even further in the direction o£ the 

previous turning, a brief nystagmus occurred, 

and the head returned to the mid-line. These 

opposite reactions, conditioned by practice, were 

accompanied by improved equilibrium during 

rotation. 

As noted earlier, Maxwell, Burke, and Reston160 reported reductions of ocular nystagmus 

from rabbits as a result of repeated rotation with 

vision permitted. Maxwell,159 Pilz,179 180 Lumpkin,155 and Henderson130 confirmed this finding. 

Maxwell and Pilz161 compared nystagmic reductions for groups of rabbits (their heads apparently were fixed) rotated in the light and total 

darkness. A greater percentage of decline in 

number of eye movements was obtained for the 

latter group. However, these findings simply 

reflected the results of the habituation series and 

optokinetic stimuli were present throughout the 
light trials. Henderson130 noted that rabbits 

which no longer showed after-nystagmus following repeated stimulation in the light would evidence a vigorous response if they were then 

blindfolded. Some further tests led him to agree 

with the conclusions of l\Iowrer169 regarding the 

influence of optokinetic stimuli. 

Maxwell, Burke, and Reston160 also reported 

that, following habituation to rotation, rabbits 

gave "normal" responses to caloric irrigations. 

Hood and Pfaltz140 made a similar observation 

with rabbits tested in the dark, and Collins42 

obtained the same results from cats. ·However, 

the animals' heads were fixed at different angles 

for rotation as opposed to caloric trials in the 

latter two investigations, and head position was 

not specified in the Maxwell, Burke, and Reston160 study. It has been suggested41 52 166 that 

differences in the orientation of specific and nonspecific gravi-receptors for the two types of test 

situations might account for the failure to obtain 

transfer of habituation from rotational to caloric 

stimulation. 

Hood and Pfaltz140 also reported that the response decline obtained by repeated rotation did 

not show recoYery upon retest two weeks later. 

Other tests showed that the interval between 

stimulations did not afi'ect the course of habituation, i.e., that the number of stimulations performed was critical regardless of the interval 

between tests. 

More recent investigations have dealt primarily with ocular nystagmus from the cat and have 

probably effected better overall control of stimulus conditions. Although Prince183 reported no 

change in the duration of after-nystagmus from 

cats subjected to over 1000 rotation tests, all later 

investigations show clear response reductions 

following repeated rotatory or caloric stimulation. In all of the studies cited below, the heads 

of the cats were fixed by special restraining techniques (almost invariably that of Henriksson, 

Fernandez, and KohuU32 ) and electronystagmog~aphical methods were used to record eye movements. Unless otherwise indicated, rotatory 

stimuli comprised accelerations and decelerations 

separated by one to three minutes of constant 

velocity. Unidirectional rotatory stimulation involved deceleration at stimulus rates below the 

threshold for eliciting nystagmus. 

8 

Crampton and Schwam70 and Crampton68 reported a marked reduction of ocular nystagmus 

from cats during the course of a 12-trial series 

of angular accelerations in darkness. Auditory 

stimuli or electric shock interspersed throughout 

a trial produced only partial recovery of habituated nystagmus. The response decline occurred 

both within a 12-trial series and over the course 

of similar series administered once a week for 

six weeks. Fairly strong doses of d-amphetamine 

injected into previously untested cats appeared 

to produce a higher-than-normal amplitude of 

nystagmus throughout habituation trials, but the 

response showed the same form of reduction as 

that of undrugged cats subjected to the same 

tests. 68 The drug does not appear to affect the 

time-course of nystagmus. 56 

McCabe and Gillingham163 reported no habituation of ocular nystagmus in ·anesthetized cats 

subjected to strong bidirectional stimuli (360°-

7200/sec2). However, unanesthetized cats showed 

marked reductions in the eye-movement response. 

Ablation experiments conducted on cats with 

suppressed nystagmus were effective in restoring 

nystagmus (i.e., releasing suppressio!)..) when the 

superior and lateral vestibular nuclei were destroyed ; the releasing effect was most pronounced 

when both nuclei together were eliminated. 

Crampton,68 Collins,42 and McCabe and Gillingham163 have defined the reduction of nystagmus in the cat as an overall suppression. The 

greatest decline occurs within the first five stimulations; slow-phase eye velocity is sharply 

reduced, duration of the response becomes attenuated, frequency declines, and secondary nystagmus (a response which follows and is opposite in 

direction to the primary responsecr., 5 ) begins 

earlier and is of lower output with stimulus 

repetition. The same effects occur with prolonged 

angular accelerations ( 36 seconds) and a progressiYely earlier peaking of the response with a 

declining output during angular acceleration becomes clearly evident with repeated tests. 5 6 118 

Crampton66 also subjected groups of cats 

treated with d-amphetamine to a unidirectional 

series of six habituation trials in total darkness. 

An evaluation of pre- and post-tests which comprised stimulation in both directions led Crampton to conclude that habituation was directionally 

specific. Brown and l\1arshall29 confirmed these 

results with d-amphetamine but reported com-
plete recovery of nystagmus after one week. 

They related the latter point to Fearing's83 84 

work on "massed" and "spaced" practice with 

pigeons and to a study by Brown25 in which 

separate series of unidirectional angular accelerations in darkness were administered to groups 

of cats. The series for each group were presented 

at different intervals (one to 14 days). An additional series was given to all cats two weeks 

later, and a final series was presented one month 

after that. The acquisition of habituation occurred equally for all groups in spite of the 

different time between series, but recovery (partial) after rest intervals was clearly affected. 

Groups with the shortest intervals between series 

showed the most recovery ; those with the longest 

intervals between series showed no recovery. 

Response reductions were also obtained by 

Collins and U pdegraff62 from both cats and dogs 

subjected to unidirectional habituation trials in 

total darkness. Duration, frequency, and slowphase measures of nystagmus all showed declines, 

with duration yielding the least reduction and 

slow-phase eye movement the most (see Figure 

3). Responses to stimulation in the opposite direction were more vigorous, but such that the 

authors concluded that habituation might be only 

relatively specific to direction. Following one 

week of rest, only partial response-recovery was 

obtained. 6

" Similarly, Winget and Smith204 reported a reduction in the duration of ocular 

after-nystagmus from restrained chickens (eyes 

closed) repeatedly decelerated from 32 rpm. 

Winget, Smith, and Kelly/05 however, indicated 

that such steady declines did not occur if animals 

were exposed to long periods of centrifugation 

( 1.5-2.0g) between habituation stimuli. These 

authors suggested that centrifugation might alter 

the functional characteristics of the labyrinth 

by inducing structural or chemical changes. 

Crampton67 examined the influence on habituation of optokinetic stimuli (room lights were on 

during accelerations and for 30 seconds thereafter) during unidirectional rotatory stimulation 

of cats. Whether the optokinetic response enhancf\d (one group) or opposed (another group) 

the vestibular nystagmus, the same amount of 

habituation was evident in pre- and post-tests 

conducted in total darkness as occurred with a 

group of cats given the same habituation series 

(eight rotations) in total darkness. 

9 

Later, Crampton and Brown69 reported that 

repeated unidirectional rotatory stimulation of 

the vertical semicircular canals (in darkness) 

had no effect on responses of the horizontal 

canals, i.e., there was no transfer of effects from 

vertical canal stimulation to the horizontal 

canals. Although these authors apparently did 

not record the vertical nystagmus, Collins52 demonstrated habituation of all aspects of that response in a series of unidirectional habituation 

trials in darkness with the animals restrained 

and placed on their sides. Pre- and post-tests 

showed that the habituation was relatively specific to the direction of nystagmus elicited during 

practice and, moreover, was relatively specific to 

the position of the otoliths and other gravireceptors (see Figure 5) ; the latter pre- to posttest comparison was accomplished by placing the 

animals on the side opposite that maintained 

during habituation (i.e., changing their positions 

by 180°), thereby stimulating the same set of 

canals, but with the otoliths and other gravireceptors in a new position. A similar study by 

Collins and U pdegraff63 demonstrated in parrots 

the same possibility of the specificity of habituation of vertical canal responses to the position 

of gravi-receptors. 

Collins47 noted no significant effect on habituation of nystagmus in darkness when physically 

equivalent accelerations and decelerations followed each other within less than a second, i.e., 

the deceleration stimulus was applied during the 

peak of the nystagmic response to acceleration, 

thereby interrupting that response; nystagmus 

occasioned by deceleration was permitted to run 

its course. Habituation was obtained for both 

directions of response (evaluated in separate 

unidirectional pre- and post-tests) and was of the 

same magnitude as that obtained both from a 

group of cats exposed to 2-minute periods of 

constant velocity between accelerations and decelerations (both directions of response were 

permitted to run their course) in a similar 

habituation series, and from another group which 

received unidirectional habituation (subthreshold 

decelerations). The latter group also confirmed 

the relative directional specificity of habituation 

(see Figure 4). 

B. Nystagmus: Caloric-Induced. With the 

exception of Dunlap's81 use of unilateral ice 

water irrigations with two rabbits, caloric hab-
VERTICAL NYSTAGMUS 

HABITUATED DIRECTION 

PRE --+-1'--~,r-vvvv-vv~vv-v~~_______.v-.-J\_ -----.I\ 

POST \~vv-Af--1[-v--r~---"------ "-J~ 

UNHABITUATED DIRECTION 

PRE~!---~~ 

POST - ~1_____ ___j\_______J__ ____A_____]L_.. ~ 

HABITUATED DIRECTION 

PRE -~ ____ ___......_--..!(~ 

POST ~tuvvtwv0,11JV{VWl~fVl~~- I~ ::I:c ITiz 

l>z 

ol> 

UNHABITUATED DIRECTION "'0~ 0~ 

(I)C 

:::j~ -, 

~0 PRE ~~~----~----------LlL.--v--

POST -IJ_jtJ\J}u\AAIL~_N~l /~_Jl __ ---J\_ 

PARROT D-12 :wL 

2sec 

FIGURE 5. Specific and non-specific gravi-receptors interact with the semicircular canals in the reduction of vertical 

nystagmus by repeated rotation of birds63 and cats."" The ocular tracings above were obtained from a parrot 

which was exposed to 15 unidirectional accelerations with its head and body fixed in a "beak down" position. 

Pre- and post-tests involved both directions of rotation with the beak down (habituated head position) and 

both directions of rotation with the beak up (unhabituated head position). Nystagmus reduction was relatively 

specific to both the head position used and the direction of nystagmus elicited during the habituation series. 

Vertical bars demarcate the acceleration period; a calibration marker appears at the bottom right of the chart. 

(Reprinted with permission from Acta Otolaryngologica.63 ) 

ituation studies of animals have been largely 

restricted to cats. Dunlap81 calorized a single 

ear of each rabbit in the light three times daily 

every other day for a total of 39 to 48 trials. 

No ocular nystagmus was elicited following the 

24th trial in one animal and the 33rd trial in the 

other. Retests a month later showed recovery; 

nystagmus was obtained during the first five to 

six days of this new series which was continued 

for one to two months. The opposite ear was 

then irrigated and yielded some response, but the 

reaction was clearly weak; several days of irri10 

gation eventually abolished this nystagmus. The 

rabbits next were rotated and showed no nystagmus to stimulation of the horizontal or of the 

vertical (animals were placed on their sides)· 

semi-circular canals. Retested six months later, 

the rabbits showed no caloric nystagmus, but 

both gave vigorous responses to rotation. The 

heads of the animals may have been in the same 

plane for both ca.loric and rotatory stimulation. 

Henriksson, Fernandez, and Kohut132 calorized 

cats in the light and reported a reduction of 

nystagmus (particularly maximum eye-speed) 
following several stimulations. In another study 

which permitted vision/33 10 irrigations, alternately warm to one ear and cool to the other 

(each driving nystagmus in the same direction), 

produced more habituation and at a faster· rate 

than that obtained by 10 irrigations of one ear 

with a single temperature of stimulus; a following irrigation drove ny~tagmus in the opposite 

direction and produced vigorous nystagmus, i.e., 

there was no transfer of habituation to the unpracticed direction of responses. In another 

series of tests, cats were given 10 irrigations of 

one ear alternately with cool and warm water; 

another group received a single temperature of 

stimulus alternately to each ear. Both procedures reduced maximum eye velocity, but the 

second procedure seemed more effective, in agreement with the related finding noted above. Further tests showed that the same pattern of 

habituation was obtained whether 10 irrigations 

were separated by 5-minute intervals or by 24-

hour intervals, and that response declines persisted for two to three weeks. Transfer of 

unidirectional habituation was extensively examined. Different groups were given 10 calorizations of a single ear with cool or with warm 

water; the same ear was then irrigated with the 

opposite stimulus temperature (driving nystagmus in the unpracticed direction) ; normal responses were obtained. Other animals received 

10 cool stimuli in the right ear and then, in separate tests, warm water to the same ear and both 

warm and cool water to the left ear. Nonequivalent stimuli (i.e., stimuli which would 

drive nystagmus in the unpracticed direction) 

produced vigorous responses, regardless of the 

ear tested; equivalent stimuli produced a reduced 

response. When animals were given 10 irrigations alternating warm and cool water to· one 

ear or using cool water alternately presented to 

each ear (in both cases, nystagmus was driven 

alternately to the left and the right) a bidirectional decline was obtained and any following 

irrigation stimulus (cool or warm applied to 

either ear) revealed complete transfer of habituation. Fernandez and Schmidt86 87 noted that the 

reduction of nystagmus was particularly apparent in the frequency of eye movements and in 

velocity of the slow and fast components, while 

duration and amplitude of nystagmus might not 

be affected. Habituation was also obtained from 

cats with total ablation of the necortex, with 

11 

unilateral or bilateral ablation of the temporal 

lobes, and with hemidecortication.86 87 

Proctor and Fernandez184 examined blindfolded cats with unilateral irrigations and obtained a clear response decline in frequency and 

amplitude of nystagmus (the latter was not obtained in the studies which permitted vision), 

and in the velocity of both the slow and fast 

components. After habituation, blingfolds were 

removed and an additional test was conducted. 

Neither direction, nor frequency, nor total number of eye movements was affected (i.e., they 

were still at the habituated level), but both 

amplitude and velocity of nystagmus were increased. Pre- and post-tests indicated transfer 

of habituation for an equivalent stimulus presented to the non-habituated ear; non-equivalent 

stimuli presented to either ear showed some response reduction (partial transfer). Tests conducted two to 12 days later showed only partial 

response recovery. 

Collins41 confirmed the response reduction with 

unilateral caloric irrigations in the dark and 

noted that the greatest decline occurred within 

the first five trials. The relative directional 

specificity of reduction was also confirmed by use 

of equivalent and non-equivalent unilateral stimuli following habituation. Further, unidirectional rotation tests in total darkness, conducted 

before and after the habituation series, showed 

only a small change in nystagmic output. Thus, 

contrary to Dunlap's81 findings with rabbits, the 

response decline following caloric stimulation did 

not show significant transfer to rotational stimuli. 

However, the animals' heads were positioned 

differently for the two stimulus conditions in 

Collins'41 study. 

In other transfer experiments, Capps and 

Collins3a and Mertens and Collins166 employed 

both bilateral (simultaneous stimulation of one 

ear with warm, and the other with cool water) 

and unilateral irrigations in total darkness. A 

15-trial series produced significant decrements in 

slow-phase eye movement and frequency of nystagmic beats (duration was not markedly affected) for either unilateral or bilateral stimulation (see Figure 6). Retention tests were 

conducted one to four weeks later and showed 

partial recovery which appeared somewhat 

greater after four weeks than after two weeks; 

howe,·er, nystagmus appeared to decline more 
TRIAL STIMULUS: R- IW FOR 15 SEC 

17 

TWO WEEKS LATER 

STIMULUS : L- IW FOR 15 SEC 

POST -I 

~~~,N 

~·~-Jw~~ 

STIMULUS: R-IW FOR 15 SEC 

~~-----

POST- 2 

~/V 

CAT NO. BC -73 

FIGURE 6. Caloric nystagmus during the first and last trials of a 17-trial series of unilateral ice water irrigations 

of the right ear. The response is clearly reduced following the caloric habituation series. After two weeks, 

there is some recovery of the responses from the right ear, but the directional specificity of the reduction is 

still evident when comparisons are made with responses from the left ear. Vertical bars indicate the end of 

the irrigations; optokinetically-obtained calibration markers appear at the right, below each pair of tracings. 

(Reprinted with permission from Acta Otolaryngologica.") 

rapidly with several repetitions of the retentiontest irrigations. In examining transfer, Capps 

and Collins33 gave three groups of cats a preand post-test comprising a mild unilateral stimulus (26° C. to the right ear) ; one group received 

an habituation series of 15 such irrigations, the 

other two groups received a bilateral series 

(26° C. to the right and 50° to the left ear) of 

15 habituation trials for a duration of 25 seconds 

in one case, and 30 seconds in the other ( increasing the duration of a bilateral stimulus up to at 

least 30 seconds produces a stronger nystagmus50). Responses to the post-test unilateral 

stimulus were reduced to an approximately 

equivalent level for all three groups. Thus, 

12 

habituation to bilateral calorizations transferred 

to a unilateral stimulus of less intensity. Similarly, three new groups received a strong unilateral stimulus (ice water) during pre- and 

post-tests; one group was exposed to unilateral 

ice water habituation, the other two were habituated with bilateral irrigations of 15 and 20 

seconds duration, respectively. Although bilateral stimuli produced weaker responses initially 

than did the unilateral ice water irrigation, responses to the post-test unilateral stimulus were 

reduced approximately equally for all groups. 

Thus, habituation to bilateral calorizations transferred completely to a unilateral stimulus of 

greater intensity. 33 Further, no effect of the 
habituation series was evident for optokinetic 

responses (rotation of a striped drum). 

Later, three different intensities of unilateral 

stimulation were applied to three groups of cats 

in a 15-trial habituation series.166 Pre- and posttests indicated that all of the unilateral habituation stimuli produced as great a response reduction to bilateral caloric stimuli as did a series of 

15 bilateral irrigations. Thus, unilateral caloric 

habituation transferred to bilateral caloric stimulation. Additional pre- and post-tests involved 

rotation. Bilateral caloric habituation appeared 

to have relatively little effect on responses to 

rotation. Similarly, a group of cats exposed to 

a series of unidirectional rotations were given 

pre- and post-tests with bilateral calorizations 

(all driving nystagmus in the same direction): 

habituation was obtained to the rotatory stimulus, but no significant effects on caloric nystagmus were obtained.166 These results confirmed 

previous findings by Collins41 42 which showed 

relatively little inter-modal transfer of habituation (head position was different for caloric and 

rotational trials in these studies), but did not 

agree with Dunlap's81 results. 

A study by Collins44 examined the effects of 

"double irrigations" (simultaneous binaural irrigation with water of equal temperatures) on 

habituation in the dark. The "double irrigation" 

drives the cupulae in opposite directions, thereby 

cancelling horizontal nystagmus (weak vertical 

nystagmus may sometimes be produced, c£., 

TRIALS PRE-TEST CALORIC : 2s•c TO RIGHT EAR FOR 30 SEC 

PRE -I 

PRE-3 

'mvL_ POST-TEST CALORIC : 26°C TO RIGHT EAR FOR 30 SEC 2 SEC 

POST-I 

POST-3 

CAT NUMBER 20- E 

FIGuRE 7. Repeated peripheral stimulation does not necessarily cause a reduction of vestibular nystagmus. The 

tracings depicted above are from a cat which received 15 "double irrigations" (administration of 26° C. water 

to both ears simultaneously) between the unilateral pre- and post-tests. Vertical bars denote the end of the 

irrigation period; all trials were in total darkness. (Reprinted with permission from Acta Otolaryngologica!4 ) 

13 
Riesco-Mac-Clure186 ). Pre- and post-tests with 

unilateral irrigations of the same stimulus tem- · 

perature indicated that the seri~s of :'dou~le 

irrigations" produced no nystagmic habituatiOn 

(see Figure 7) . 

V. Survey of Studies of Man. 

A. Nystagmus: Rotation-!nd1.KJed. As noted 

earlier, Ruppertl89 and Barany10 reported a unidirectional reduction of nystagmus from dancers 

who habitually whirled in one direction. In 

more recent times, Fukuda, Tokita, Hinoki, and 

Kitahara98 have cited shorter-than-normal durations of nystagmus not only for dancers but for 

athletes as well. School boys98 and gymnasts188 

involved in vestibular programs of self-stimulation in play activities or prescribed physical 

training are reported to show progressively attenuated nystagmus which is interpreted as an 

improvement of the labyrinthine function by 

training; athletic ability is concomitantly enhanced. 98 188 

In laboratory studies, Griffith106 rotated subjects (including himself) in the light and reported attenuation of the duration of nystagmus 

and of the number of eye movements both within 

a daily series of tests and from day-to-day; only 

minor recovery was evident after two months of 

rest. He also noted that, when a rotating subject 

was stopped and then moved back one-quarter 

turn, a markedly reduced nystagmus duration 

was obtained (this probably has implications for 

"head-free" rotation studies of animals). Four 

years later, with no intervening tests, Griffith107 

conducted another series of rotations on himself 

in the light and reported some recovery of nystagmus duration and number of eye movements 

(the response had been abolished after 135 trials 

in the earlier study), but the nystagmus was not 

as vigorous as it had been initially and now only 

35 trials were required to abolish the response. 

Six subjects in another study104 were given a 

daily series of rotations. After-nystagmus was 

timed in the light following one revolution of 

the turning device; when subjects no longer 

showed any nystagmus, the number of revolutions was increased to two, then to three, and so 

on. Progressively more trials were required to 

inhibit after-nystagmus completely as the numbe-r of revolutions increased from one to two, two 

to three, and so on to nine to ten. None of the 

14 

subjects experienced vertigo at any time ~nd.' at 

the end of the study, none showed past-pomtmg. 

Griffith103 also reported that visual far-fixation 

~fter a brake deceleration produced twice the 

duration and frequency of nystagmus as did 

near-fixation. Subjects with their gaze directed 

laterally (in the direction of the fast-phase) 

showed an enhanced duration, but this, too, became attenuated with repeated practice. Preventing visual fixation (e.g., with 20-diopter 

lenses) doubled the duration of after-nystagmus. 

However, even in the absence of visual fixation, 

duration of nystagmus declined with repeated 

elicitation. 

Ho1sopple137 reported attenuation of afternystagmus with repeated practice in the light for 

several rates of deceleration. Subjects were then 

rotated while wearing 20-diopter len~>es and, although they showed an increased nystagmus 

time, durations were still below initial reactions~ 

One subject was then blindfolded and the duration of his sensation timed; it showed little difference from pre-habituation levels. Holsopple137 

also reported that rotation in the opposite direction yielded vigorous after-nystagmus. He attributed this to the fact that acceleration and 

deceleration stimuli were not separated by a sufficient period of time. He restated this view in 

another paper139 and particularly emphasized the 

importance of nystagmus running its course (i.e., 

that the response must not be interrupted by an 

opposing stimulus) for habituation to occur. 

More recently, Brown26 obtained significant response reductions for both directions of nystagmus during a series in which accelerations were 

immediately followed by decelerations in total 

darkness. Collins47 reported a similar finding 

with cats; however, the form of the habituated 

response curve appears different in comparing 

cat and man. Holsopple138 also noted that nystagmus time may be seriously affected by position 

of the head and that "practically every subject 

exhibits some tendency toward head movem~nts 

during rotation." 

Dorcus77 rotated a group of subjects with heads 

fixed, and another with heads free. Duration of 

after-nystagmus was observed during 50 rotations over a 10-day period. For both groups, 

duration declined with repetition; responses in 

the opposite direction, however, were not affected. 

The "head-fixed" group clearly showed a greater 

reduction than did the "head-free" group. Ad-
ditional trials were then conducted by fixing the 

heads of those previously rotated with heads free, 

and freeing the heads of those previously rotated 

under the "head-fixed" condition. The responselevel which had been reached at the end of the 

habituation series was not changed by changing 

the head condition. Dorcus77 concluded that the 

two types of habituation were different. 

Mowrer170 braked subjects to a stop from 12 

rpm and observed the duration of after-nystagmus. During 12 trials, in a room with striped 

walls, subjects were alternately required ( 1) to 

keep their eyes always open, and (2) to have 

eyes closed during rotation but open when the 

chair stopped. The latter condition produced 

greater after-nystagmus than the former, but no 

decrease with repetition, while the former condition produced some reduction of response duration. ~fowrer170 then gave another series of 12 

rotations to two groups of subjects. Trials were 

alternately conducted with (1) eyes closed during 

rotation but open when the chair stopped, and 

(2) eyes open and the subject fixating on the top 

of his finger (one group) or eyes, open but a 

drum over the subject's head (the other group). 

Both of the latter conditions prevented optokinetic nystagmus and permitted visual still-fixation. There was no difference among the conditions with respect to duration of after-nystagmus. 

Mowrer170 concluded that the reduction of afternystagmus was due to the post-stimulus persistence tendency of the optokinetic response (i.e., 

optokinetic after-nystagmus). 

Dodge74 conducted the first extensive habituation study in which visual stimulation was excluded by subjecting himself to over 600 rotation 

trials during a 6-day period. Using sudden 

starts and stops separated by approximately 15 

seconds of rotation at 20 rpm, he recorded nystagmus with eyes closed and reported abolition 

of the response to deceleration. By changing 

the direction of rotation, he found a 50% reduction of nystagmus from pre-habituation levels. 

However, there were complicating factors present: decelerations were introduced while the 

response to acceleration was still in progress, and 

alertness was probably uncontrolled. \Vith respect to the latter, Dodge• noted that "the rotation experiment had a soothing soporific character . . . (that) did not carry over into reversed 

rotation or accidental interference with the 

customary speed." 

15 

Cupulometric data from 320 normal subjects 

tested with Frenzel-type glasses were obtained 

by Aschan, Nylen, Stahle, and WerslUl.8 Dura· 

tion of nystagmus was directly observed. Using 

four to six stimulus rates, the authors noted a 

directional preponderance which depended upon 

whether subjects were first rotated to the right 

or to the left for each stimulus rate. The durations of nystagmus to the first direction of rotation were significantly longer than those obtained 

to the second direction of rotation for all but the 

highest stimulus value ( 52° /sec). No such effect 

was noted for the duration of the afternystagmus. 

Suzuki and Totsuka194 used standard cupulometric procedures, and recorded nystagmus from 

behind closed lids. Subjects were given a series 

of 10 or more abrupt stops from constant velocities of five or of 10 rpm. No decline in response 

duration was reported for the higher stimulus 

rate, while the lower rate showed considerable 

trial-to-trial variation; in addition, irregular 

nystagmus was frequently associated with the 

shorter durations (probably due to arousal factors). However, Fluur and Mendel93 reported a 

reduction in the duration of recorded nystagmus 

(closed eyes) after 10 to 12 brake decelerations 

from 14 rpm. No technique for controlling 

alertness of the subjects was noted. Additional 

subjects were braked to a stop from 5 rpm, but 

no indication of habituation was evident after 10 

trials. Unilateral caloric stimuli administered 

before and after the 15 rpm rotation series 

showed reduced durations for t}J_e direction of 

nystagmus elicited during the habituation series, 

and a longer nystagmus time for the opposite 

direction in most subjects. Several subjects 

showed a pre- to post-test decline in duration to 

all unilateral caloric stimuli. Similar results 

were reported by Pfaltz and Arx177 who obtained 

a reduction in nystagmus during the course of 10 

unidirectional rotations in darkness. Post-tests 

elicited both directions of nystagmus and showed 

a preponderance favoring the non-practiced direction; the difference was still evident two weeks 

later. 

Collins43 gave 10 subjects each a series of 200 

unidirectional accelerations (decelerations were 

subthreshold) over a 10-day period. Nystagmus 

was recorded with eyes open in total darkness 

and subjects were assigned a variety of tasks to 

be performed during stimulation. Tests con-
ducted the day before and the day after the 

habituation series indicated that there was not 

so much a decline in nystagmus as there were 

changes in the form of the response. Specifically, for the "prn,cticed" direction, slow-phase 

eye displacement declined ( 30%) throughout the 

response. However, the number of eye movements increased throughout the stimulus period 

and for several seconds thereafter (although total 

frequency showed a slight decline) ; the response 

also appeared more regular and perhaps better 

"tuned" to the stimulus (see Figure 8). These 

changes were somewhat gr~ater for the "practiced" direction, but were clearly evident for both 

directions, and were still present one month later 

with no intervening trials. 

TRIALS PRE 

1-CW 

2-CCW 

3-CW 

4-CCW 

Wendt203 reported a similar finding using 

oscillatory stimulation: with repeated testing 

(subjects' eyes were closed), the amplitude of 

slow-phase eye movements declined and the number of fast phases increased until, finally, the 

original form of the nystagmus was lost. Both 

Collins43 51 and W endt203 have noted that repeated elicitation of nystagmus from alert subjects in darkness produces, as one major effect, 

increasingly greater fast-phase activity which 

modifies the form of the response until, conceivably, the nystagmic aspect may no longer be 

evident following a very large number of stimulus repetitions. More recently, Torok197 and 

Johnson and Torok143 noted an increased frequency of nystagmus following repeated angular 

stimulation. 

TEST 20-DE 

I 

I 

I 

I 

POST-I TEST 

1-CW 

2-CCW 

3 - cw -i-~""'-'-.,../"-~""" N" "'JVv..IV'J'.J'-N'-A.r-N'N 

4-CCW 

POST-2 TEST 

,_ cw 

2-CCW ~-~~~~~~~~~~--~~~~~~~~~--~ 

3-CW 

4-CCW 

SUBJECT KS : STIMULUS 4.1• I SEC2 FOR 13 SEC 

I 

I 

I 

I 

I 

I 

I 

I 

FIGURE 8. Tracings of nystagmus obtained from a subject performing mental arithmetic with eyes open in darkness. A 10-day series of 200 CW accelerations (all decelerations were subthreshold) occurred between the pretest and the post-1 test and produced an increase in the frequency of eye movements. Post-2 tests were conducted one month later with no intervening trials. Vertical bars demarcate the period of acceleration; 20° 

calibration markers are at the end of each tracing. (Reprinted with permission from Acta Otola.ryngologica!') 

16 
-·Perhaps the most striking examples of the 

effects of repeated angular accelerations on 

human nystagmic responses may be found with 

figure skaters. Skaters have been regarded both 

anecdotally and as. the resl'!lt of some evaluations162 168 as having acquired considerable or 

complete vestibular suppression as a result of 

their spinning experiences. }yhen tested in total 

darkness, however, skaters gave vigorous nystagmic responses to a variety of angular stimuli.46 51 

When compared with ordinary subjects tested in 

the laboratory (in total darkness), the skaters 

showed significantly less slow-phase eye displacement and as high or higher a frequency of nystagmus during the early part of the response 

than did the ordinary subjects.51 Tracings also 

appeared more regular for the skater group. 

These comparisons between skaters ("practiced" 

subjects) and non-skaters ("unpracticed" subjects) show considerable similarity to the findings discussed earlier in which pre- to post-test 

comparisons of the same subjects were made after 

200 unidirectional rotations.43 Apparently most 

figure skaters spin CCW on ice (there are notable exceptions, and few, if any, either practice 

or develop a facility for spinning well in both 

directions. Since their on-ice spinning rate is 

too high to permit "visual spotting," they use 

visual fixation almost invariably during one direction of eye-movement (i.e., following deceleration). However, no consistent directional differences appeared for skaters in duration of 

nystagmus, slow-phase eye displacement, or frequency of eye movements as a result of angular 

acceleration in total darkness.51 

These results indicate that vestibular nystagmus (in the absence of visual stimulation) is not 

readily suppressed in alert subjects as a result of 

considerable experience with angular accelerations, whether that experience occurs in darkness 

or with opportunities for visual fixation. The 

response appears modified, but in a dynamic 

fashion rather than as the result of an overall 

suppression. 

As noted earlier, Wendt202 claimed that nystagmus generated in total darkness would not be 

abolished in alert subjects. However, he indicated that, with opportunities for visual fixation, 

the visual stimuli would eventually become predominant and markedly interfere with nystagmus. A number of studies in which subjects 

were allowed opportunities for visual fixation 

have reported significant declines (or abolition) 

of nystagmus. 77 106 138 139 Perhaps th~ best example of such habituation can also be found with 

figure skaters. Both in the laboratory (caloric 

and rotational stimulation) and following on-ice 

spins, skaters demonstrate almost total suppression of vestibular nystagmus when they have 

fixed visual references.46 162 The longest duration of nystagmus recorded (by meails of telemetry) from skaters following on-ice decelerations 

from 235-278 rpm was about five seconds; other 

skaters g~ve just a few beats of nystagmus before 

ON-ICE SPINS 

EYES OPEN 

EYES CLOSED 

~' J'l ~~~~\ ;\f{: ;: , _,J"'~v fr/ r;,1r·1 , 1 (r '· .r/>u'~ r:. , .r ·.. (' r!: ri:f 11 rJvj ~ u\ ~ t). ~ r: M: I I~,) j ! I_ J~' \ 'J 

1

•J 't.Jf.f!H':JJi' 11 \('1,J!i\IJ":H1'/'Jj'lf{~ j\!~~~ •J-;{~·~\(\1 ~~\!~f\ 

,NtfV'J\!\fVV\J\ .. J\J,.f\jV\\l'vJ-1·\j'\J'-!\~\f\v\t·J\.j"-i'"'',"'~~w,,rJ\-JJ\~~,.J~ 

FIGURE 9. Eye-movement tracings obtained by means of telemetry during on-i(·e spins performed by a figure skater. 

Each strip of tra(·ings represents 33 seconds of recording. Vertical bars demarcate the period of spinning. After-

·nystagmus is markedly suppressed during visual fixation.C'" ... 

17 
visual fixation terminated any apparent eye 

movement.46 However, removal of the opportunities for visual fixation by means of eye closure would reinstate a vigorous nystagmic 

response (see Figure 9). )fore recently, Fukuda, 

Tokita, Aoki, Watanabe, Hishida, Tashiro, 

Miyata, and Mazuoka,97 Osterhammel, Terkildsen, 

and Zilstorff,174 Dix and Hood,73 and Tokita, 

Aoki, ·watanabe, and Miyata196 reported no afternystagmus (or only a beat or two of eye movement) from ballet dancers whose eyes were open 

following their pirouettes, but vigorous nystagmus when their eyes were closed. Previously, 

Tschiassny199 had noted that a post-rotatory nystagmus could be obtained from a ballet dancer 

if "visual spotting" was not permitted. 

The findings with figure skaters might lead 

one to conclude that total or almost total suppression of nystagmus may require repeated vestibular stimulation with opportunities for visual 

fixation. Such ·suppression is visual inhibition 

of the response rather than vestibular inhibition, 

and the ability to exercise substantial control 

over vestibular eye movements does not seem to 

generalize completely to situations in which 

vision is not permitted.* In fact, one study27 

reported no influence on nystagmic responses in 

darkness of several types of visual stimulation 

during repeated rotation (a small, dim target 

light, an illuminated enclosure, and full room 

lighting). However, the habituation series for 

* Generalization of nystagmic modifications from dark 

to light conditions is also minimal, at least after a short 

series of habituation stimuli. Marshall and Brown158 

rotated subjects in an illuminated endosure before and 

after a series of 10 habituation trials employing identical stimulus rates. One group received the habituation 

series with the enclosure illuminated (and visual stillfixation possible), the other group was in total darkness. 

During all trials, subjects signalled their estimates of 

turning velocity. Both groups showed a significant reduction in slow-phase eye displacement during the 

habituation series. In the post-test (enclosure illuminated), the group habituated in total darkness showed 

no significant change in slow-phase output from the 

pre-habituation level; the group habituated in illuminatio;n, of course, had significantly reduced scores. 'l'his 

lack of transfer from "dark" to "light" conditions might 

be accounted for by the fact that, of itself, visual fixation on objects produces a marked decrease of the slowphase excursion of the eyes, and the reduction obtained 

after a short series of rotations in the dark may not be 

sufficient to influence noticeably the greater attenuating 

effects of visual still-fixation. 

18 

the several tested groups comprised only six trials 

for a given direction of nystagmus and the 

angular accelerations used (24° /sec 2 for 10 seconds) induced incidents of nausea and vomiting 

when either the room or the enclosure was lighted. 

In evaluating the relative lack of generalization of eye-movement control by figure skaters 

from the on-ice condition (vision permitted) to 

the laboratory situation (vision excluded), several factors must be considered: (1) during onice spins skaters actively coordinate control of 

rotation, while in the laboratory they are passively rotated; (2) the stimulus rates during 

on-ice spins are considerably higher than those 

generated in the laboratory; ( 3) some laboratory 

findings with ordinary subjects117 and with aerobatic pilots3 4 32show directionally specific effects 

related to visual stimulation. 

·with respect to the latter, Aschan3 4 reported 

a directionally specific shortening of the duration 

of nystagmus ( cupulometry) from fighter pilots, 

with the reduction related to the direction in 

which the pilots most frequently rolled their aircraft during various flight maneuvers. Caporale 

and Camarda32 obtained a similar finding from 

acrobatic pilots using accelerations and decelerations of 1°, 3°, and 6° /sec 2 separated by 90 seconds of constant velocity at 15 rpm. Recordings 

from behind closed eyes showed a clear directional difference in intensity of nystagmus. Pilots 

who flew on the left during various aircraft 

formations (and therefore kept their heads 

turned to the right during flight to maintain 

visual contact with the aircraft ahead of them) 

showed weak left-beating and normal rightbeating nystagmus. Pilots who flew on the right 

side of formations (with their heads, therefore, 

turned to the left) evidenced the reverse of this 

directionally specific difference. Other studies 

of pilots have not noted such consistencies. 22 23 178 

Guedry117 controlled arousal by tasks and used 

total darkness during one direction of nystagmus 

(e.g., GW acceleration), while visual stimulation 

occurred during the other direction of the response (e.g., CW deceleration). Subjects were 

given 80 such rotation trials within a 4-hour 

period. Tests before and after the SO-trial series 

were conducted entirely in darkness; results indicated a pre- to post-test decline in slow-phase 

nystagmus of about 20% for the direction repeatedly elicited in darkness (in good agreement 

with the results obtained in darkness by Col-
lins43 ) and a pre- to post-test decline of about 

50% for the direction of nystagmus repeatedly 

inhibited by visual stimulation. 

The findings of Aschan,3 4 Caporale and Camarda,32 and Guedry117 do not appear to agree 

with results obtained from figure skaters, who 

show equivalent nystagmus regardless of direction when tested in the laboratory, although on 

ice they make use of visual information only (or 

at least primarily) during deceleration responses. 

The lack of agreement may be due not only to 

active vs. passive rotation and to marked differences in stimulus rates, but also to the fact that 

the skaters do perform on-ice turning maneuvers 

in both directions and the rate of these turns (as 

opposed to rates during their free-style spins) 

may be equivalent to laboratory stimuli. In addition to these factors, ( 1) it is possible that 

visual stimulation may simply speed up the 

habituation process for the practiced direction of 

turn and, with many repetitions, transfer of the 

nystagmic response modification may become 

complete so that both directions of nystagmus 

are equi val en tly modified; and ( 2) the sensory 

pattern is different for skaters spinning on ice 

as compared with laboratory rotations. In the 

latter case, nystagmus was always elicited with 

the cupula in its resting position. On ice, skaters 

build up their acceleration until they feel it has 

reached its peak and then bring themselves to a 

stop; the deceleration (followed by visual stillfixation) is thus introduced with the cupula away 

from its resting position, perhaps at a point of 

maximum deflection. 

All of the above has been concerned with what 

Guedry117 has termed "simple vestibular stimulation," i.e., stimulation by angular acceleration 

about a vertical axis primarily of a single pair 

of semicircular canals. "Complex vestibular 

stimulation" may involve simultaneous activation 

of other pairs of canals and of specific and no)lspecific gravi-receptors. In this regard, mention 

should be made of studies involving rotation 

about a horizontal axis14 15 64 65 116 and combinations of angular and centripetal accelerations.18 48 

Nystagmus is clearly affected by these conditions. 

In the former case, nystagmic eye movements did 

not cease during constant velocities ranging up 

to several minutes in duration, and a relatively 

abrupt termination of nystagmus and sensation 

occurred upon stopping. In the latter cases, the 

intensity, plane, and direction of nystagmus 

19 

changed as centripetal acceleration increased with 

the lateral canals in the plane of rotation. 

Bergstedt20 21 has shown that the intensity of 

both positional and caloric nystagmus is increased 

with increasing . g: the latter finding was confirmed by Orlov172 and by Yuganov,209 with 

Yuganov also reporting a decrease in postrotational nystagmus during weightlessness. 

Thus, it is clear from these and other 

studiese.g., 52 es 164 175 that nystagmus can at least 

be affected by other motion- or position-sensing 

systems and, indeed, horizontal nystagmus can 

even be elicited by periodic linear accelerationsY1 

"Complex vestibular stimulation" can also be 

accomplished by means of simultaneous motion 

about more than one axiscr., 136 or by active or 

passive head movements during rotary motion.121 124 Such simultaneous stimulation of 

more than one pair of semicircular canals, the 

so-called Coriolis vestibular effect, produces (in 

addition to sensations) nystagmus with a predominantly vertical component. It should also 

be noted that there is a lack of congruency between signals from the semicircular canals and 

those from other sensory systems (e.g., otoliths 

and proprioceptors) under these unusual stimulus conditions. In examining the question of 

habituation, most "Coriolis studies" have been 

conducted with opportunities for visual fixation. 

Subjects have been permitted to move about 

freely in a rotating room,121 or have made restricted head movements during rotation according to set procedures,114 119 122 or have been 

exposed to passive movement (chair tilts) as well 

as making active head tilts.80 

Subjects learn to adapt to the unusual vestibular effects produced by moving about in a 

lighted rotating room. During long-term studies 

(64 hours to 12 days) standard head-movement 

tests with control of arousal were introduced during the course of the prolonged rotational period 

as well as before and after rotation (i.e., with no 

rotation). Nystagmus was recorded in total 

darkness during these standard tests and showed 

an overall decline during rotation.121 Following 

cessation of rotation (in a static situation) subjects demonstrated spontaneous compensatory 

nystagmus as a result of head movements,115 121 

That is, following the adaptation period, while 

at a standstill, standard head movements produced a nystagmus opposite in direction to that 

which should have occurred had the same head 
movement been made during rotation. Retention 

and transfer of habituation effects were examined 

by Guedry,m who tested subjects in darkness 

before and after a 12-day exposure to living in 

a CCW rotating room. A clear attenuation of 

nystagmic responses to head tilts during CCW 

rotation was obtained in post-habituation tests; 

little pre- to post-test change was obtained for 

head tilts during CW rotation. Additional posttests were conducted two days, three weeks, and 

three months later. Nystagmic responses to head 

movements during CCW rotation showed progressive but incomplete recovery; however, nystagmus obtained as a result of head movements 

during CW turning fell well below the pre-test 

values in these later tests, to a level approximately equal to CCW responses, as if to establish 

a balance at the habituated level. 

Studies of Coriolis effects with restricted head 

movements (in one quadrant of the frontal plane 

only) have been of shorter durations (four to 

seven hours). Although a large number of head 

movements was made in the lighted room by the 

subjects, no spontaneous compensatory nystagmus 

was obtained following the rotation periods.119 122 

However, standard head-movement trials in darkness during rotation were conducted after about 

200 head movements in the light and showed a 

general pre- to post-test suppression of nystagmus for the practiced direction of head movement, but there was no effect of the habituation 

trials on nystagmus generated by head movements in the unpracticed quadrant. 

Further research confirmed and expanded these 

findings. Guedry114 had a group of subjects tilt 

their heads and return them to upright at set 

intervals with their eyes closed. Other subjects 

performed the same head movements but were 

required to solve problems with multiple-choice 

answers which were projected on a screen during 

the head movements. All head movements were 

made in a single quadrant with most subjects 

completing 100 tilts and 100 returns. Before and 

after the 100-cycle series, subjects performed 

mental tasks in darkness and made head movements in both the practiced and unpracticed directions. A clear pre- to post-test reduction in 

recorded nystagmus (approximately 70%) occurred in the practiced quadrant for subjects 

who performed the visual problem-solving tasks; 

the unpracticed quadrant showed only a 15% 

reduction. A similar quadrant-specific reduction 

20 

was evident in pre- to post-test comparisons for 

the group which had performed the head movements with eyes closed, but the reduction in the 

practiced quadrant was only about 12%; the unpracticed quadrant showed essentially no pre- to 

post-test change. 

B. Nystagm;us: Oaloric-/ndU(}ed. Although 

angular acceleration is the adequate stimulus for 

the semicircular canals, the most frequently used 

method of eliciting nystagmus in clinics is that 

of thermally-produced endolymph movement in 

the canals. The recommended procedure is to 

use water of temperatures 7o C. above and below 

body temperature.88 Cool water (30° C.) drives 

nystagmus (fast-phase) away from the irrigated 

side, warm 'Yater (44° C.) drives it toward the 

irrigated side. Although the stimulus is a gross 

one, it has the advantage of permitting the testing of each ear separately. 

Almost all studies of the effects of repeated 

caloric irrigations on nystagmic reactions have 

involved unilateral stimulation. Loch and 

Haynes154 timed nystagmus from subjects wearing Frenzel glasses and reported no decline as a 

result of irrigations performed once dai~y for 

five to six days, although they noted a change in 

the form of the response (nystagmus became 

more regular). With subjects' eyes closed, 

Stahle193 found no clear response decline for four 

irrigations, two of which drove nystagmus to the 

left and two to the right. However, he noted 

that dysrhythmia might occur with repeated 

stimulation. Lidvall149 150 151 152 performed a series of studies which indicated that .a relatively 

small number of stimuli (four to six) would 

significantly shorten nystagmus duration (recorded from behind closed eyes) and reduce the 

frequency of nystagmus, while increasing latency 

and dsyrhythmia, whether the intervals between 

stimuli were short (six to eight minutes) or long 

(one to 25 days). 

Fluur and Mendel90 91 also recorded eye movements from behind closed lids and obtained significant reductions (about 30%) in response 

duration (increasing dysrhythmia made quantification of other aspects of nystagmus impractical) following a series of eight to 12 irrigations. 

In their first study, subjects received unilateral 

habituation trials. In post-habituation tests, the 

majority of subjects showed a response reduction 

from pre-test levels for unilateral stimuli to 
either ear which drove nystagmus in the habituated direction, and a longer nystagmus time for 

unilateral stimuli which drove nystagmus in the 

opposite direction. Other subjects showed a 

pre- to post-test decline for either cool or warm 

stimulation in either ear. In the second study,91 

subjects were habituated with eight to 12 unilateral stimulations of one ear; post-tests yielded 

the same results as that obtained from the majority of subjects in the previous study. Next, 

a new series of unilateral stimuli drove nystagmus in the opposite direction. Post-tests indicated a decline for that direction of nystagmus 

irrespective of the ear irrigated, but responses in 

the opposite direction (habituated in the first 

series of stimulations) were now back to the 

initial, pre-habituation levels. The authors concluded that "in a person already habituated by 

repeated monaural irrigation with hot water it 

is not possible to superimpose a habituation to 

cold water in the same ear without influencing 

the response to the primary habituation." They 

theorized that habituation influenced the spontaneous activity levels in the two labyrinths and 

disrupted the balance between them. 

However, Pfaltz and Arx171 obtained a directional preponderance of nystagmus following a 

series of unidirectional rotations, and reported 

no reversal of this difference following a series 

of unilateral caloric stimuli which drove nystagmus in the opposite direction, although the caloric 

response declined with repetition (all tests in 

darkness). They noted that a shift in the ratio 

between the two directions of nystagmus could 

be obtained by repeated unidirectional angular 

accelerations, but not by repeated unilateral 

caloric irrigations ("Eine Verschiebung des 

quantitativen VerhaJtnisses zwischen Rects-und 

Linksnystag:rims kann im Gegensatz zur widerholten Dreheizung nicht mittels aufeinanderfolgender monauraler thermischer Reize erzielt 

werden. "). A series of binaural irrigations, on 

the other hand, produced a preponderance of 

nystagmus favoring the unpracticed direction of 

eye movement. 

Forssman, Henriksson, and Dolowitz95 and 

Forssman94 -investigated the effects on caloric 

habituation o£ 12 consecutive irrigations in darkness and in illumination (the first and twelfth 

trials were always in darkness). They reported 

approximately equivalent reductions in duration 

and velocity of nystagmus for the two conditions 

21 

(25% for duration; 55% for velocity). In addition, laterotorsion (i.e., deviation of the header., 131 ) declined by approximately 40%. Dysrhythmia during light trials was considerable (probably due to only intermittently effective visual 

inhibitation), but during dark trials was very 

moderate. 

In the above investigations only Lidvallt52 

reported the_ use of any alerting technique. After 

demonstrating a progressive decline in the number of eye movements during four irrigations, 

Lidvall152 noted that an additional trial during 

which subjects performed mental calculations 

resulted in an immediate restoration of the response. A study by Collins45 examined the influence of an extensive series of unilateral 

irrigations ( 10 daily for four days) on responses 

to both unilateral and bilateral irrigations. One 

group of subjects was tested in total darkness 

while performing various tasks; the other group 

actively sought to control nystagmus by fixating 

on ceiling markers in a lighted room. During 

pre- and post-tests, each subject received six 

irrigations ; two were bilateral (warm and cool 

water simultaneously presented to the two ears), 

one driving nystagmus to the left, the other to 

the right; the remaining four were unilateral 

irrigations with cool and warm water presented 

to each ear successively. Results indicated essentially no effect of the habituation series on the 

duration of nystagmus for either group. For the 

group habituated in total darkness, no significant 

decline in slow-phase eye displacement but a 

significant overall increase in eye-movement frequency appeared (see Figure 10). For the group 

habituated in the light, no pre- to post-test 

change in frequency of nystagmus occurred, but 

slow-phase measures declined significantly. For 

both groups, changes were somewhat greater for 

the three stimuli provoking responses in the same 

direction as that of the habituation trials. For 

the light group no recovery of the slow-phase 

loss was evident after one month of rest; similarly, for the dark group, the increase in frequency of nystagmus was still evident upon 

retest a month later. 

Collins, Schroeder, and Mertens61 performed 

a similar series of 40 irrigations with subjects 

actively fixating on ceiling markers; one group 

was given unilateral irrigations, the other bilateral stimulation; nystagmus was driven to the 

left in both cases. During pre- and post-tests, 
PRE TRIAL 

POST TRIAL 

STIMULUS: 30• C TO RIGHT EAR FOR 30 SEC 

FIGURE 10. Caloric nystagmus recorded before and after an habituation series of 40 unilateral irrigations (all 

trials in darkness with the subject's eyes open). Dysrhythmia and an overall reduction of nystagmus are not 

necessary consequences of repeated vestibular stimulation; an increase in the number of eye movements, as depicted above, may occur. Vertical bars indicate the end of the irrigation; 20° calibration markers appear at 

the beginning of each tracing. Each strip of tracings represents 33 seconds of recording."'·· •• "' 

subjects received the series of six cool and warm 

unilateral and bilateral stimulations noted above. 

Results indicated that, for both groups of subjects, nystagmus declined unidirectionally. A 

control group received only the pre- and posttest irrigations and showed no change. 

The same study also included four rotation 

trials prior to any pre-test irrigations; the rotations were repeated after all post-test irrigations. 

No significant changes were evident in nystagmic 

output for either direction of rotation-induced 

nystagmus as a result of the caloric trials. 

C. Subjective ReMtions: Rotation-Induced. 

The sensations of motion accompanying semicircular canal stimulation appear to be more 

readily affected by repeated exposure to either 

angular accelerations or calorizations than are 

nystagmic eye movements. Of considerable interest is the fact that they may follow a timecourse different from that of nystagmus. 

Griffith,104 106 who reported attenuation of nystagmus following cessation of rotatory stimulation in a lighted room, also noted a decline in the 

sensation of apparent motion with repeated 

stimulation. Although Hallpike and Hood126 

found an attenuation of turning sensations that 

was directionally specific (subjects were rotated 

with eyes closed), their findings may be more 

closely related to adaptation effects than to 

habituation. These investigators used a short 

test stimulus before and after a prolonged stim22 

ulus (e.g., 2° /sec 2 for 75 sec) and found that, 

when the post-test stimulus was in the same direction as the prolonged stimulus, rotary sensations were shorter than the pre-test level; when 

the post-test stimulus was in the direction opposite that of the prolonged stimulus, reactions 

were of normal (pre-test) duration. 

A single subject with eyes covered and head 

approximately erect was given two series of CW 

rotations by Meda.165 The first series covered 40 

days and comprised 290 trials (stops and starts 

were sudden and apparently separated by one 

minute of constant velocity at 30 rpm). A fairly 

systematic decline in the duration of the sensation following deceleration was obtained both 

within days and from day-to-day. Tests conducted before and after habituation showed little 

or no change in (1) the duration of aftersensations with the head anteverted so that the 

lateral canals were perpendicular to the plane of 

rotation, (2) the duration of sensations occasioned by head movements either during rotation 

or immediately after deceleration, and (3) the 

duration of after-sensations following CCW deceleration. The lack of transfer of habituation 

from one set of semicircular canals to another 

set, or between reactions from one set of canals 

and Coriolis-induced. responses has been confirmed in other studies of nystagmus from man 

and cat. 5 2 69 115 119 However, the failure to obtain 

a reduction to CCW deceleration is surprising 

smce the subject was apparently exposed to an 
equivalent stimulus (CW acceleration) during 

the habituation series, at an equivalent rate 

(sudden starts and stops) under identical visual 

conditions (eyes covered). A second series was 

initiated with the subject's head ventrally flexed. 

After 100 rotations the after-sensation was reduced by about 50%. Tests with head movements 

during and following rotation showed no clear 

effect of the habituation series on the duration 

of these Coriolis sensations. Additional tests 

conducted at intervals of one to three months 

with the subject's head erect finally showed full 

recovery of the duration of the after-sensation. 

In comparing the technique of cupulometry to 

the Barany test procedure, Groen and J ongkees108 

demonstrated that the sensation cupulogram obtained before and after a set of three CW and 

three CCW Barany spins (stops from 30 rpm) 

showed a marked decline. They felt that the 

Barany-type stimulus damaged the vestibular 

organ and that a maximum velocity of only 10 

rpm should be used prior to braking subjects to 

a stop. However, Brand24 obtained response declines for post-rotational turning sensations both 

within a daily series of brake decelerations from 

10 rpm (or less) and from one test day to the 

next. 

Aschan,3 using cupulometry, reported reduced 

durations of sensation to rotational stimuli from 

fighter pilots. Unlike the directionally specific 

reductions in nystagmus which he found for this 

group, sensations for both directions of angular 

stimulation were attenuated. Similarly, Dearnaley, Reason, and Davies71 reported shorter 

durations for experienced pilots than for trainees 

in the vestibular sensations occasioned by 1-

minute long, 45-degree banks in an aircraft; 

within each group there was no difference between left and right turns. The differences 

between pilots and students were present whether 

subjects' eyes were closed or visual references 

were available, although increasing the amount 

of visual information decreased the sensation for 

both groups. Preber182 had examined pilot 

trainees before flight training and followed-up 

a group which showed severe airsickness during 

the training period. These subjects, as a group, 

haa longer durations of sensation during turning 

tests conducted prior to flight training than did 

trainees who did not get air sick; however, after 

adapting to the flying situation, tests showed a 

23 

decline in duration of sensation. Previously, 

de Wit2°6 had reported progressively greater 

cupulogram slopes in comparisons of a group of 

sailors who had never been seasick, a group of 

students, and a group of sailors who were chronically seasick. 

Guedry, Collins, and Sheffey120 performed a 

50-trial habituation series spaced over five days 

with trials alternately in total darkness and with 

a 5-second period of room illumination following 

deceleration. Pre- and post-tests in total darkness showed a decline of approximately 50% for 

total subjective displacement. Partial recovery 

was evident nine days later with no intervening 

trials. 

Benson13 gave subjects (closed eyes) impulsive 

decelerations and, three seconds after they had 

reached a stop, had them shake their heads for 

two seconds. The duration of post-rotatory sensations was reduced after the head-shaking period. With repetition, post-rotatory sensations 

declined both with and without head shaking, 

but declined independently. There was no difference between non-aerobatic aircrew and ordinary subjects. 

Collins' study/3 employing 200 unidirectional 

habituation trials in total darkness with subjects 

performing various attention-demanding tasks, 

showed a directionally specific reduction of 39% 

in peak subjective velocity and 37% in total subjective displacement for the practiced direction 

of angular acceleration. There was no pre- to 

post-test- difference for the unpracticed direction 

(see Figure 11). One month later, with no intervening trials, total subjective displacement was 

only 27.5% less, and peak subjective velocity 

only 16.5% less, than the pre-test levels for the 

practiced direction; the unpracticed direction 

still showed no· change from the pre-lest level. 

Thus, the subjective reaction declined in a directionally specific fashion, without the subjects 

attending to the sensation, and in the absence of 

vision; the response showed partial recovery after 

one month of rest. 

Professional figure skaters report some initial 

dizziness when they resume spinning routines 

after vaction periods of one to three months. In 

skating trim, they appear to experience only very 

mild and brief dizziness following on-ice spins, 

but if they close their eyes upon stopping, clear 

vertiginous sensations occur. Similarly, while 
70 

60 

50 

40 

:so 

20 

0 

8 10 

w 

(/) 

II: 0 

~ 

(/) 80 w 

w 

II: 

(l) 50 I!! 

~ 

>- 40 

... 

u 

~ 50 

> 

w 20 

> i= 

(.) 10 w 

jiJ 

~ 

(/) 0 

~ 80 II: 

w 

~ 50 

40 

:so 

20 

10 

PRE 

AVERAGE FOR 

8 SU8JECTS 

5 10 IS 20 25 50 55 40 45 50 55 80 65 

5 10 ~ 20 25 50 55 40 q 50 55 80 • 

POST-2 

TIME IN SECONDS 

-PRACTICED 

Ofii£CTIOH 

~ UNPRACTICED 

DIII£CTION 

FIGURE 11. Subjective velocity estimates made by subjects before (pre) and after (post-1) a series of 200 

CW accelerations (all decelerations were subthreshold). Post-2 tests were conducted one month later 

with no intervening trials. The habituation series 

produced a clear, directionally specific reduction in 

the intensity of the turning sensation (but not in 

its duration) ; a month of rest produced considerable 

recovery. (Reprinted with permission from Acta 

Otolaryngologioa.") 

they can perform gracefully with open eyes following such spins, closing their eyes produces a 

loss of balance and an inability to maneuver.46 

24 

In laboratory tests (total darkness) of figure 

skaters, clear turning experiences were reported 

to rotation and there was no difference in the 

duration of left vs. right turning sensl).tions.51 

When compared with ordinary subjects, however, 

skaters had significantly shorter durations to 

stimuli ranging from 5° /sec2 for 18 seconds to 

90° /sec 2 for one second. It is of considerable 

interest that the differences between the two 

groups were proportionately greater for the 

higher rates of angular acceleration. 51 

D. The Oculogyral Illusion. During rotational stimulation, an object with a minimal visual surround (a small dim light source in an 

otherwise dark room) appears to move in a definite pattern although it and the observer are in 

fixed positions.102 This apparent motion, the 

oculogyral illusion (OGI) has been identified 

with the sensation of turning rather than with 

nystagmus30 72 203 (however, see also reference 

36). Brown and Guedry28 examined the duration 

of the OG I before and after short series of rotations ( 1) in total darkness, ( 2) with a target 

light present, and (3) with five seconds of room 

illumination following cessation of rotation 

(target light present). Marked declines in OGI 

duration occurred for the latter two conditions. 

Previously, Guedry110 had reported a successive 

shortening of the duration of the illusion during 

a series of trials in which conditions of total 

darkness and of brief illumination of the test 

room (shortly after deceleration) were alternated. Directional specificity of this decline in 

the condition which employed vision was noted 

in later studies111 112 113 and it was observed that 

a decline of the OGI at one stimulus rate produced a greater response reduction to a stimulus 

of lesser intensity and a lesser response reduction 

to a stimulus of greater intensity.112 Subsequently, Clark and MacCorquodele35 reported no 

shortening in the duration of the OGI in three 

trained subjects who observed the illusion with 

a more complex visual stimulus (the lighted outline of a cube) during 276 accelerations and 276 

decelerations. A recent study by Brown and 

Crampton27 showed no differential effects on 

duration of the OGI of rotating subjects in total 

darkness, with the OGI, with an illuminated 

enclosure, or in full-room illumination; however, 

only six habituation trials were conducted for 

each group in the direction under consideration. 
E. Ooriolis Vestibular Sensations. The OGI 

has also been used in studies of habituation of 

Coriolis vestibular responses produced by head 

movements during constant rotation. The array 

of effects which occurs depends to some extent 

upon the kind of visual information available 

during the head movements.48 The sensations 

produced (as well as the apparent movement of 

a target light) are combinations of displacement 

and acceleration (see Figure 12 and reference 

53), e.g., tilting the head to the right during CW 

rotation produces a sensation of tilting backward 

and accelerating upward (much like a sharp 

climbing maneuver in an aircraft). Guedry and 

Montague124 reported reduction of the apparent 

@-+@ Rotator at standstill. 

@-+@ CW acceleration (5° /sec2 for 18 sec). 

displacement of a target light with repeated 

head movements. Graybiel, Guedry, Johnson, 

and Kennedy101 rotated subjects in the light for 

a 64-hour period during which they made voluntary head movements or were passively tilted in 

a special chair. Tests during the experiment involved the OGI (the lighted outline of a cube) 

with the room otherwise dark. Magnitude estimates of the illusion declined for all subjects. 

In addition, a conditioned compensatory reaction 

was obtained; when the room was at a standstill 

at the end of the experiment, subjects made head 

movements and reported OGI effects which were 

opposed in direction to those which would have 

been produced had the same head movement been 

Subject detects start of turning, direction of turn (to the right), and increasing velocity. 

@-+® Period of constant velocity at 15 rpm. 

@-+@ Subject perceives velocity of right turn diminishing and, finally, all turning sensations cease. 

@-+® Subject makes head movements upon given signals. 

Head movement: Upright 

Sensation: Level 

Tilt 

Right 

Climb 

@-+® CW deceleration (5° I sec2 for 18 sec). 

Return to Tilt 

Upright Forward 

Dive Roll to 

Right 

Return to Upright 

Upright 

Roll to 

Left 

Level 

Subject detects start of turning, direction of turn (to the left), and increasing velocity. 

®-+@ Rotator at standstill. 

Subject perceives velocity of left turn diminishing and, finally, all turning sensations cease. 

FIGURE 12. The subjective reactions occasioned by angular accelerations, angular decelerations, and head movements during rotation."' Note that: The sensations are reversed if CCW rotation is used; returning the head 

to upright from a tilt to the right is equivalent to tilting the head to the left; the sensation experienced as a 

result of deceleration is directionally opposite that resulting from the acceleration and is perceived as a speeding up rather than a slowing down. 

25 
made during rotation. Similar conditioned compensatory reactions were obtained for nystagmus.121 Further evidence was obtained for 

conditioned OGI effects in studies of shorter 

duration (four to eight hours of rotation) with 

voluntary head movements restricted to a single 

quadrant in the frontal plane.119 122 

Guedry114 exposed two groups of subjects to a 

100-cycle series of head movements restricted to 

a single quadrant; one group performed the 

movements with eyes closed, the other group 

solved problems projected on a screen during the 

head tilts. Tests were conducted before and 

after the 100-cycle series (1) during rotation and 

(2) in a static situation. During. rotation, there 

were clear pre- to post-test reductions in OGI 

for head movements in the practiced quadrant 

and a lesser reduction for the unpracticed quadrant among subjects in the "vision" group; the 

"darkness" group showed less reduction. In 

static post-tests, the "vision" group reported OGI 

effects principally in the practiced quadrant; the 

"darkness" group evidenced little or no OGI 

reactions. 

Related to the above, but without using the 

OGI, Guedry115 gave pre- and post-tests in darkness to subjects who had lived in a lighted, rotating room (10 rpm CCW) for 12 days. The 

subjects rated the intensity of sensations occasioned by specific head movements during both 

CW and CCW rotation. Little or no post-test 

sensations were obtained during CCW rotation; 

sensations from head tilts during CW rotation 

were as strong or stronger than the pre-test 

levels. Additional post-tests conducted two days, 

three weeks, and three months later showed recovery, but not to the pre-test levels. 

F. Subjective Reactions: OalorU;-/nduoed. 

Sensations generated by caloric irrigations are 

not uniform among subjects and may even differ 

from one irrigation to the next for the same 

subject.45 Frequently a directional component of 

the experience cannot be specified.182 Although 

bilateral stimulation (simultaneous presentation 

of cool water to one ear and warm to the other) 

frequently produces sensations of apparent 

angular motion about an earth-vertical axis, both 

bilateral and, more often, unilateral calorizations 

will result in experiences of tilting, floating, 

dizziness, "arcing" (successive apparent motion 

through a relatively small angle), combinations 

26 

of these, or even apparent turning about an 

earth-horizontal axis. 45 

LidvalJ149 150 151 153 reported a considerable decline in "vertigo" with as few as four unilateral 

irrigations and noted that the decline was specific to the direction of cupula deflection in the 

irrigated earl50 i.e., after vertigo habituation of 

one ear with a cool stimulus, a warm stimulus 

applied to that ear, or any stimulus applied to 

the opposite ear would produce a strong vertigo 

response. Forssman, Henriksson, and Dolowitz95 

and Forssman94 noted declines in vertigo ratings 

exceeding 80% after 12 irrigations, whether suqjects were tested in darkness or in an illuminated 

room. Hinchcliffe135 obtained ratings of caloric 

vertigo induced by unilateral stimul~tion and 

reported marked declines in intensity ratings 

following five irrigations; a second se:r:ies administered on the following day showed partial recovery for the first trial and a rapid decline for 

the remaining tests (subjects' eyes closed). 

Collins45 kept subjects alert during a 40-trial 

habituation series (one group was tested in total 

darkness, another group was engaged in active 

visual fixation) and tested responses in total 

darkness before and after the habituation tri~ls. 

Since the pre- and post-tests involved all combinations of irrigations (unilateral and bilateral, 

cool and warm), the effects of the 40-trial series 

(cool water to the right ear) on responses in the 

same and in the opposite "directions" could be 

evaluated. For both groups of subjects, directionally specific effects were evident. There was 

an average increase in latency of the sensation, 

and a decline in its duration and rated intensity 

for all stimuli eliciting responses in the same 

direction as the habituation trials. Responses in 

the opposite direction were either less affected 

(although showing some decline) or, in the case 

of subjects who received the 40-trial series in 

darkness, unilateral stimulations produced ratings o£ greater intensity than the pre-test levels. 

For both groups, a 1-month rest interval resulted 

in some recovery or complete recovery of the 

response. 

Collins and Mertens58 expanded and partially 

replicated the above study. Using the same 

caloric pre- and post-test procedures, they examined two groups which engaged in active 

visual fixation during a 40-trial habituation 

series (one group received unilateral stimulation, 

the other bilateral stimulation) and a control 
(/) 

(/) 36 

w 

z 32 N 

N 

0 28 

lJ.. 

0 24 -(/) 

0 20 z 

0 

u 

w 16 

(/) 

z 12 -

z 

0 8 

~ 4 a= 

::::> 

0 0 

BILATERAL LIGHT GROUP 

0 

/\ 

/ \ / \ / \ / \ / 

0 \ 

\ 

\ 

\ 

o-----o 

6..._, 

..... .......... '6 

----._._A-----A 

4 7 10 

36 

32 

28 

24 

20 

16 

12 

8 

4 

0 

UNILATERAL LIGHT GROUP 

o--o 

• • 6--6 

A & 

N=l2 

4 

DAY I 

DAY 2 

DAY 3 

DAY 4 

7 10 

TRIAL 

FIGURE 13. The mean duration of dizziness calculated from the reports made by 12 subjects in each of two test 

groups during caloric irrigations. Subjects fixated on a ceiling marker throughout each of 10 calorizations per 

day for four consecutive days. The bilateral group received simultaneous irrigations of the two ears (right 

30° C.; left 44° C.) ; the unilateral group received 30° C. irrigations of the right ear only. The subjective reaction shows considerable decline over the test series.<'··"' 

group which received only the pre- and posttests. During the 40 visual-fixation trials, the 

duration of "dizziness" and of the apparent 

movement of the fixation point showed an irregular but progressive decline during each 10-

trial day, and over the four test days (see Figure 

13). The pre- and post-test data (obtained in 

darkness) showed essentially no change in sensation ratings made by the control group. In 

agreement with previous work,45 repeated unilateral stimulation (cool water to the right ear) 

produced relatively little pre- to post-test change 

in sensation-intensity for caloric stimuli which 

elicited responses in the direction opposite those 

of the habituation series. Postctesf responses to 

the unilateral and bilateral stimuli which involved cool water in the right ear showed significant declines; warm water to the left ear (a 

stimulus "equivalent" to that used in the habituation series) did not produce a decline in sensa27 

tion. This latter result (a lack of transfer) does 

not agree with the previous finding of Collins,45 

but does agree with Lidvall's reportl50 that unilateral caloric habituation of vertigo is specific to 

the cupula deflection of the repeatedly stimulated 

ear. The group which received bilateral habituation demonstrated significant declines in vertigo 

( 49-62%) for all three stimuli which produced 

reactions in the same direction as the habituation 

series, and a uniform increase (22-32%) in sensation ratings for the three non-equivalent 

stimuli. 

G. Special Effect8 of Brief Period8 of Vi8ual 

Fiwation on Ve8tibular Re8pon8e8. Only a few 

studies have examined the effects of brief periods 

of visual stimulation on nystagmic and subjective 

reactions. Brown and Guedry28 and Guedry,111 

112 113 as indicated earlier, used brief periods of 

illumination in studies of the oculogyral illusion. 

Wendt202 noted that, although post-rotational 
nystagmus was inhibited during a period of 

visual fixation, the response was quickly reestablished during a succeeding period of darkness. 

Guedry, Collins, and Sheffey120 confirmed 

Wendt's202 statement, but found that the response 

was not restored to the level of an uninterrupted 

reaction a:pd that the sensation of turning showed 

no recovery. 

Collins51 introduced three seconds of room illumination one second after various rates of deSUBJECT JS 

DARK TRIAL 

~ 

j..JJ 

40" L 

I SEC 

-t~ 

------------------Jr--------~r~_____r;~--~rr-______ r ~---------~r- ~~ _____ __,r ..----

LIGHTS ON 

--~~~--~--~-r--~--~~-----r------r---

-----~ ~--------~rr---------------- r .- .-----------~ _____r-.-------' 

__ .,._)........___ ____r--1'-- ------r-~---.r--r----J 

_]~ r~------~~------~ ~----------~ ~-------~ ~-------~rr·· ______ ____r ___ _ 

LIGHT TRIAL 40"L 

I SEC 

FIGURE 14. The influence on nystagmus and subjective turning of a period of room illumination during a CW deceleration. Vertical bars through the tracings demarcate the deceleration period. The deflections on the lines 

just below the nystagmus tracings represent the recorded signals of turning•'·· •• 109 experienced by the subject; 

downward deflections indicate a sensation of turning left, upward deflections indicate a sensation of turning 

right. Note in total darkness the prolonged primary nystagmus, the lack of secondary nystagmus, and the indication of the usual left-turning sensation from this subject. The period of room illumination during the light 

trial produces a reversed (optokinetic) nystagmus and a reversal of the indicated direction of turn. Subsequent extinguishing of the lights reverses the direction of primary nystagmus for only a few seconds; the primary response is then replaced by a long-lasting secondary nystagmus. Moreover, this subject did not experience the leftward turning which the canals would have been signalling after the lights were turned off; a 

long-duration right-turning sensation was reported (subjects called out the direction of turn in addition to 

manual signals). Other subjects reported no sensation for several seconds after the period of room illumination, and then experienced strong sensations of turning to the right.er .. •• 

28 
celeration; trials were otherwise in darkness. 

Subjects actively fixated on wall markers during 

illumination and attempted to control completely 

their eye movements. Room illumination (subjects were at a complete standstill) substantially 

reduced on-going nystagmus; during the subsequent period of darkness, nystagmus recovered, 

but never to the level of an uninterrupted response. Of perhaps greater significance, the 

shortened primary nystagmus was frequently replaced very quickly by a secondary nystagmus 

which appeared more vigorous than the secondary 

reactions obtained (but much later in time) during trials in total darkness (see Figure 14) . 

(Markaryan151 has also noted strong secondary 

nystagmic reactions following angular stimulation and a period of visual fixation.) The sensation of turning was suppressed during the 

visual stimulation and, during the subsequent 

period of darkness, was reinstated (although 

considerably reduced) in only a small percentage 

of cases. 

More recently, using "prolonged" angular 

stimuli (20 ·seconds or more), Collins49 introduced room illumination for various durations 

during the deceleration period ; the final six 

seconds of deceleration and the subsequent period 

at a standstill were always in total darkness. 

Under these conditions, subjects could see themselves decelerating (although in darkness the 

vestibular signals would have produced a sensation of accelerating in the opposite direction; 

see- Figure 12), and an optokinetic nystagmus 

was generated opposite to the nystagmus which 

the semicircular canals would have initiated. 

Room lights were turned off during the last few 

seconds of deceleration, and vestibular nystagmus 

quickly replaced the optokinetic response. However, in comparison with an uninterrupted response, nystagmic output was at a much-reduced 

level, was significantly shorter in duration, and 

more frequently was succeeded by a vigorous 

secondary nystagmus. Following the period of 

room illumination (during the last six seconds 

of deceleration in darkness) many subjects reported no sensation; some reported a brief sensation of turning in the true direction (in 

opposition to the vestibular signals). Very 

shortly after the termination of deceleration a 

marked and prolonged "secondary" sensation 

was reported by almost all subjects. 

29 

These data have been interpreted as indications 

that secondary reactions are of central origin, in 

agreement with Aschan and Bergstedt.5 In addition, it has been suggested that they may occur 

as a result of "prolonged" neural activity in the 

primary direction,49 that secondary reactions are 

processes which oppose primary reactions (perhaps occurring as the consequence of a central 

imbalance produced by "prolonged" unidirectional activity), and that visual information 

(under some conditions) is centrally integrated 

and enhances this already on-going process, 

thereby attenuating the primary response.49 51 

VI. A Modified View of "Habituation." 

The term "habituation" has been used throughout this report to identify a series of repeated 

stimulations or to describe the effects of such a 

series on various responses. Most investigators 

carefully restrict the meaning of the term to 

"response reduction" or, considering habituation 

to represent a valid class of learning, cite 

Thorpe's195 definition ("a tendency merely to 

drop out responses"). Although vestibular research findings appear to share many of the 

general characteristics ascribed to other habituation phenomena,74 127 185 such definitions fail to 

describe adequately the dynamic processes of 

change which are evident as a result o"f repeated 

vestibular stimulation under at least some conditions. For example, repeated exposure of man 

to Coriolis stimulation in the light reduces nystagmus and subjective reactions in both light and 

darkness; an overall suppression appears to 

occur. However, closer examination indicates 

that a conditioned compensatory reaction has 

developed to oppose these responses.114 121 There 

is no simple dropping out of responses; instead 

there is a gtadual inhibition of the original response as the opposed reaction becomes more 

fully developed. These opposed reactions have 

appeared most clearly under two nonexclusive 

conditions: ( 1) when there is an element of conflict between vestibular and visual signals (and 

perhaps others of a sensory nature), (2) where 

the organism is attempting to adapt to an unusual vestibular environment. In darkness, nystagmus repeatedly elicited by simple vestibular 

stimulation is not simply reduced in alert subjects; the form of the response is changed and 

the change appears to be due to increased activity 

of the fast phase of the eye movement which, 
concomitantly, reduces the amount of slow-phase 

eye excursion.41 51 With very brief responses, 

such as those elicited by mild turns of short arc, 

increasingly more frequent fast phases may gradually obliterate the original form of nystagmus. 203 

"Active modification" would more closely describe the effects of repeated stimulation on 

human vestibular responses. 

The above suggests the possibility of more 

than one kind of vestibular "habituation." In 

the section concerned with arousal, presented at 

the beginning of this paper, the notion of psychological or situational "habituation" was discussed in terms of arousal factors. In addition, 

repeated vestibular stimulation of animals produces some effects apparently different from 

those obtained from human subjects. Cats, for 

example, show a very rapid reduction of all 

measures of ocular responses (in darkness or in 

light) similar to what might occur with a nonalert human subject, even though this overall 

reduction occurs in animals which seem alert, or 

which have received an analeptic drug, and in 

which various sensory methods of arousal do not 

significantly restore nystagmus. Thus, in spite 

of a rich history of research, there remain considerable gaps in knowledge concerning specific 

effects of repeated stimulation on vestibular reactions and, moreover, there remain important 

questions regarding the extent to which changes 

in the reaction patterns of animals can be generalized to human response patterns. It is suggested, however, that central processes are 

activated as a result of repeated vestibular stimulation, and that limiting the term "habituation" 

to a "simple dropping out of responses" masks 

dynamic changes and interactions which occur 

in humans as these responses become modified. 

REFERENCES 

1. Abels, H.: Uber Nachempfindung im Gebiete des 

Kin!lsthetischen und statischen Sinnes. Ein Beitrag 

zur Lehre vom Bewegungschwindel (Drehschwindel), Z. PSYCHOL. PHYSIOL. SINNESORG., 

43:268-289 and 374-422, 1906. 

2. Angyal, A., and N. Blackman: Vestibular Reactivity 

in Schizophrenia, ARCH. NEUROL. PSCHIAT., 

44:611-620, 1940. 

3. Aschan, G.: Response to Rotatory Stimuli in Fighter 

Pilots, ACTA OTOLARYNGOL. (Stockholm), Supplement 116, 24-31, 1954. 

4. Aschan, G.: Habituation to Repeated Rotatory 

Stimuli (Cupulometry) and the Effect of Antinausea Drugs and Alcohol on the Results, ACTA 

OTOLARYNGOL. (Stockholm), 64 :95-106, 1967. 

5. Aschan, G., and M. Bergstedt : The Genesis of 

Secondary Nystagmus Induced by Vestibular Stimuli, ACTA SOC. MED. UP SAL., 60 :113-122, 1955. 

6. Aschan, G., M. Bergstedt, and J. Stahle: Nystagmography : Recordings of Nystagmus in Clinical 

Neuro-Otological Examinations, ACTA OTOLARYNGOL. (Stocl;:holm), Supplement 129, 1-103, 1956. 

7. Aschan, G., B. L. Finer, and K. E. Hagbarth: The 

Influence of Hypnotic Suggestion on Vestibular 

Nystagmus, ACTA OTOLARYNGOL. (Stockholm), 

55:97-110, 1962. 

8.- Aschan, G., C. 0. Nylen, J. Stahle, and R. Wersall: 

The Rotation Test : Cupulometric Data from 320 

Normals, ACTA OTOLARYNGOL. (Stockholm), 

42:451-459, 1952. 

II II 

9. Bach, L. : Uher kunstlich erzengten Nystagmus bei 

normalen Individuen und bei Taubstummen, ARCH. 

F. AUGENHLK., 30:10-14, 1895. 

30 

10. Barany, R.: Weitere Untersuchungen {lber den vom 

Vestibular-apparat des Ohres reftektorisch ausgel8sten Nystagmus und seine Begleiterscheinungen, 

MONATS. F. OHRENHK., 41 :477-526, 1907. 

11. Barber, H., and G. Wright: Release of Nystagmus 

Suppression in Clinical Electronystagmography, 

LARYNGOSCOPE, 77:1016-1027, 1967. 

12. Bekesy, G. Von: Subjective Cupulometry, ARCH. 

OTOLARYNGOL., 61 :16-28, 1955. 

13. Benson, A. J. : Modification of Labyrinthine AfterSensations on Shaking the Head. FPRC Report 

1210, Ministry of Defense (Air), London, 1962. 

14. Benson, A. J., and M. A. Bodin: Effect of Orientation to the Gravitational Vertical on Nystagmus 

Following Rotation about a Horizontal Axis, ACTA 

OTOLARYNGOL. (Stockholm), 61:517-526, 1966. 

15. Benson, A. J., and M. A. Bodin : Interaction of 

Linear and Angular Accelerations on Vestibular 

Receptors in Man, A,EROSPACE MED., 37:144-154, 

1966. 

16. Benson, A. J., and J. J. Brand : Some Effects of 

1-Hyascine Hydrobromide on Post-Rotatory Sensation and Nystagmus in Man, QUART. J. EXP. 

PHYSIOL., 53 :296-311, 1968. 

17. Benson, A. J., A. B. Goorney, and J. T. Reason: 

The Effect of Instructions Upon Post-Rotational 

Sensations and Nystagmus, ACTA OTOLARYNGOL. 

(Stockholm), 62:442-452, 1966. 

18. Benson, A. J., and T. C. D. Whiteside: The Effect 

of Linear Acceleration on the Response to Angular 

Acceleration in Man, J. PHYSIOL. (London), 

156 :6-7P, 1961. 
19. Bergmann, F., and J. Gutman: Effect of Largactil 

on Various Forms of Nystagmus, PSYCHOPHARM. 

SERV. CENT. BULL., 2 :57-58, 1962. 

20. Bergstedt, M. : Studies of Positional Nystagmus in 

the Human Centrifuge, ACTA OTOLARYNGOL. 

(Stockholm), Supplement 165, 1-144, 1961. 

21. Bergstedt, M.: The Effect of Gravitational Force 

on the Vestibular Caloric Test, ACTA OTOLARYNGOL. (Stockholm), 53 :551-562, 1961. 

22. Bertoni, R.: Les Epreuves d'Equilibration 1t !'Aide 

du Fauteuil Pendulaire Appliquees au Personnel 

Navigant, REV. MED. AERONAUT. SPATIALE, 

9:67-70, 1970. 

23. Bertoni, R., and G. Bremond : Le Comportement de 

l'Appareil d'Equilibration Chez les Pilotes d'Acrobatie Aerienne, REV. MED. AERONAUT. SPA-

'.riALE, 9 :29--31, 1970. 

24. Brand, J. J.: The Effect of Repetition on Measurements of Post-Rotational Turning Sensation and 

Nystagmus in Man, QUART. J. EXP. PHYSIOL., 

53 :312-326, 1968. 

25. Brown, J. H.: Acquisition and Retention of Nystagmic Habituation in Cats With Distributed Acceleration Experience, J. COMP. PHYSIOL. PSYCHOL., 60 :340-343, 1965. 

26. Brown, J. H.: Interacting Vestibular Stimuli and 

Nystagmic Habituation, ACTA OTOLARYNGOL. 

(Stockholm), 62:341-350, 1966. 

27. Brown, J. H., and G. H. Crampton: Concomitant 

Visual Stimulation Does Not Alter Habituation of 

Nystagmic, Oculogyral or Psychophysical Responses 

to Angular Acceleration, ACTA OTOLARYNGOL. 

(Stockholm), 61:80-91, 1961. 

28. Brown, R. H., and F. E. Gpedry: Influence of 

Visual Stimulation on Habituation to Rotation, J. 

GEN. PSYCHOL., 45:151-161, 1951. 

29. Brown, J. H., and J. E. Marshall: Drug Control of 

Arousal and Nystagmic Habituation in the Cat, 

ACTA OTOLARYNGOL. (Stockholm), 64:345-352, 

1967. 

30. Byford, G. H.: Eye Movements and the Optogyral 

Illusion, AEROSPACE MED., 34:119--123, 1963. 

31. Byford, G. H. : Anomalies of the Human Corneoretinal Potential. FPRC Report 1223, Ministry of 

Defense (Air), London, 1964. 

32. Caporale, R., and V. Camarda: La Funzionalita 

Vestibolare di Alcuni Piloti di Pattuglia Acrobatica, 

RIV. MED. AERON., 21 :12-36, 1958. 

33. Capps, M. J., and W. E. Collins: Effects of Bilateral 

Caloric Habituation on Vestibular Nystagmus in 

the Cat, ACTA OTOLARYNGOL. (Stockholm), 

59 :511-530, 1965. 

34. Cenacchi, V., G. Fenu, and L. Gabrielli: L'azoine 

Dell' Amfetamina Sulla Risposta Nistagmica da 

Stimoli Rotacceleratori. Studio Sperimentale Condotta Sui Coniglio, Bl)'LL. SOC. !TAL. DI BIOL. 

SPER. (Napoli), 41:527-530, 1964. 

35. Clark, B., and K. MacCorquodele : The Effects of 

Repeated Rotatory Acceleration on the Oculo-Gyral 

Illusion, J. EXP. PSYCHOL., 39:219-227, 1949. 

31 

36. Clark, B., and J. D. Stewart: Comparison of Sensitivity for the Perception of Bodily Rotation and 

the Oculogyral Illusion, PERCEP. & PSYCHOPHYS., 3 :253-256, 1968. 

37. Claude, H., H. Baruk, and M. Aubry: Contribution 

a l'Etude de la D6mence Precoce Catatonique : 

Inexcitabilite Labyrinthique au Cours de la Catatonie, REV. NEUROL., 1:976-980, 1927. 

38. Colbert, E. G., R. R. Koegler, and C. H. Markham: 

Vestibular Dysfunction in Childhood Schizophrenia, 

ARCH. GEN. PSYCHIAT., 1 :6oo-617, 1959. 

39. Collins, W. E.: Effects of Mental Set Upon Vestibular Nystagmus, J. EXP. PSYCHOL., 63 :191-197, 

1962. 

40. Collins, W. E. : Manipulation of Arousal and Its 

Effects Upon Human Vestibular Nystagmus Induced 

by Caloric Irrigation and Angular Accelerations, 

AEROSPACE MED., 34:124-129, 1963. 

41. Collins, W. E.: Nystagmus Responses of the Gat to 

Rotation and to Directionally Equivalent and NonEquivalent Stimuli After Unilateral Caloric Habituation, ACTA OTOLARYNGOL. (Stockholm), 

58 :247-258, 1964. 

42. Collins, W. E.: Primary, Secondary, and Caloric 

Nystagmus of the Cat Following Habituation to 

Rotation, J. COMP. PHYSIOL. PSYCHOL., 57:417-

421, 1964. 

43. Collins, W. E.: Task-Control of Arousal and the 

Effects of Repeated Unidirectional Angular Acceleration on Human Vestibular Responses, ACTA 

OTOLARYNGOL. (Stockholm), Supplement 190, 

1-34, 1964. 

44. Collins, W. E.: Effects of "Double Irrigations" on 

the Caloric Nystagmus of the Cat, ACTA OTOLARYNGOL. (Stockholm), 59:45-54, 1965. 

45. Collins, W. E.: Subjective Responses and Nystagmus Following Repeated Unilateral Caloric Stimulation, ANN. OTO-, RHINO-, LARYNGOL., 

74:1034-1054, 1965. 

46. Collins, W. E.: Vestibular Responses from Figure 

Skaters, AEROSPACE MED., 37:1098-1104, 1966. 

47. Collins, W. E.: Effects on Vestibular Habituation 

of Interrupting Nystagmic Responses With Opposing Stimuli, J. COMP. PHYSIOL. PSYCHOL., 

64 :308-312, 1967. 

48. Collins, W. E.: Coriolis Vestibular Stimulation and 

the Influence of Different Visual Surrounds, AEROSPACE MED., 39:125-130, 1968. 

49. Collins, W. E.: Modification of Vestibular Nystagmus and "Vertigo" by Means of Visual Stimulation, 

TRANS. AMER. ACAD. OPHTHAL. OTOLARYNGOL., 72:962-979, 1968. 

50. Collins, W. E.: Some Methodological Considerations 

In Caloric Tests of Vestibular Function. In Third 

Symposium on the Role of the Vestibular Organs 

in Space Exploration. NASA Report SP-152, 

NASA, Washington, D.C., 393-401, 1968. 

51. Collins, W. E.: Special Effects of Brief Periods of 

Visual Fixation on Nystagmus and Sensations of 

'.rurning, AEROSPACE MED., 39 :257-266, 1968. 
52. Collins, W. E.: Influence of Head Position on the 

Habituation of Vertical Vestibular Nystagmus in 

the Cat. J. COMP. PHYSIOL. PSYCHOL., 67:156-

159, 1969. 

53. Collins, W. E.: Effective Approaches to Disorientation Familiarization for Aviation Personnel. FAA 

Office of Aviation Medicine Report No. 70-17, 1970. 

54. Collins, W. E., G. H. Crampton, and J. B. Posner: 

Effects of Mental Activity Upon Vestibular Nystagmus and the Electroencephalogram, NATURE, 

190:194--195, 1961. 

55. Collins, W. E., and F. E. Guedry: Arousal Effects 

and Nystagmus During Prolonged Constant Angular 

Acceleration, ACTA OTOLARYNGOL. (Stockholm), 54 :349-362, 1962. 

56. Collins, W. E., and F. E. Guedry: Duration of 

Angular Acceleration and Ocular Nystagmus from 

Cat and Man. I. Responses from the Lateral and 

the Vertical Canals to Two Stimulus Durations, 

ACTA OTOLARYNGOL. (Stockholm), 64 :373-387, 

1967. 

57. Collins, W. E., F. E. Guedry, and J. B. Posner: 

Control of Caloric Nystagmus by Manipulating 

Arousal and Visual Fixation Distance, ANN. OTO-, 

RHINO-, LARYNGOL., 71 :187-202, 1962. 

58. Collins, W. E., and R. A. Mertens: Influence of 

Repeated Caloric Vestibular Stimulation on Both 

Caloric and Rotation Induced Vertigo. Preprints 

of the Annual Meeting of the Aerospace Medical 

Association, 146, 1968. 

59. Collins, W. E., and R. H. Poe: Amphetamine, 

Arousal, and Human Vestibular Nystagmus, J. 

PHARMACOL. EXP. THE:RAP., 138:120-125, 1962. 

60. Collins, W. E., and J. B. Posner: Electroencephalogram Alpha Activity During Mild Vestibular Stimulation, NATURE, 199 :933-934, 1963. 

61. Collins, W. E., D. J. Schroeder, and R. A. Mertens: 

Relative Specificity of Nystagmus Reduction to 

Caloric Stimuli in Humans. Preprints of the Annual Meeting of the Aerospace Medical Association, 

182, 1970. 

62. Collins, W. E., and B. P. Updegraff: A Comparison 

of Nystagmus Habituation in the Cat and the Dog, 

ACTA OTOLARYNGOL. (Stockholm), 62:19-26, 

1966. 

63. Collins, W. E., and B. P. Updegraff: Possible Interactions Between Gravi-Receptors and Semicircular 

Canals in the Habituation of Vertical Nystagmus 

in Parrots, ACTA OTOLARYNGOL. (Stockholm), 

69 :257-265, 1970. 

64. Correia, M. J., and F. E. Guedry: Influence of 

Laby-rinthine Orientation Relative to Gravity on 

Responses Elicited by Stimulation of the Horizontal Semicircular Canals. USNSAM-NASA Joint 

Project Report No. 100, Pensacola, Florida, 1964. 

65. Correia, M. J., and F. E. Guedry: Modification of 

Vestibular Responses as a Function of Rate of 

Rotation About an Earth-Horizontal Axis, ACTA 

OTOLARYNGOL. (Stockholm), 62 :297-308, 1966. 

32 

66. Crampton, G. H.: Directional Imbalance of Vestibular Nystagmus in Cat Following Repeated 

Unidirectional Angular Acceleration, ACTA OTO--

LARYNGOL. (Stockholm), 55 :41----48, 1962. 

67. Crampton, G. H. : Effects of Visual Experience on 

Vestibular Nystagmus Haituation in the Cat, ACTA 

OTOLARYNGOL. (Stockholm), 55:516-526, 1962. 

68. Crampton, G. H.: Habituation of Ocular Nystagmus 

of Vestibular Origin. In M. B. Bender (Ed.), The 

Oculomotor System. New York, Harper & Row, 

832-346, 1964. 

69. Crampton, G. H., and J. H. Brown: Repeated 

Vertical Semicircular Canal Stimulation Does Not 

Habituate Horizontal Nystagmus in Cat, ACTA 

OTOLARYNGOL. (Stockholm), 58:441-448, 1964. 

70. Crampton, G. H., and W. J. Schwam: Effects of 

Arousal Reaction on Nystagmus Habituation in the 

Cat, AMER,. J. PHYSIOL., 200 :29-33, 1961. 

71. Dearnaley, E. J., J. T. Reason, and J: D. Davies: 

The Nature and Duration of After-Sensations Following the Cessation of Turning in- a- Chipmunk 

Aircraft, AEROSPACE MED., 33:1224--1229, 1962. 

72. Dishoeck, H. A. E. van, A. Spoor, and P. Nijhoff: 

The Optogyral Illusion and Its Relation to the 

Nystagmus of the Eyes, ACTA OTOLARYNGOL. 

(Stockholm), 44 :597-607, 1954. 

73. Dix, M. R., and J. D. Hood: Observations Upon the 

Nervous Mechanism of Vestibular Habitu~tlon, 

ACTA OTOLARYNGOL. (Stockholm), 44 :31'0-318, 

1969. 

74. Dodge, R.: Habituation to Rotation, J. EXP. 

PSYCHOL., 6:1-35, 1923. 

75. Doesschate, G. ten, and J. ten Doesschate: The 

Influence of the State of Adaptation on the Resting 

Potential of the Human Eye, OPHTHALMOLOG ICA, 132 :308-320, 1956. 

76. Doesschate, G. ten, and J. ten Doesschate: The 

Influence of the State of Adaptation on the Resting 

Potential of the Human Eye (2nd communication), 

OPHTHALMOLOGICA, 134 :183-193, 1957. 

77. Dorcus, R. M.: A Comparison of Post-Rotation 

Nystagmus Duration for Repeated Stimulation 

With the Head Fixed and Free, J. COMP. 

PSYCHOL., 7:177-179, 1927. 

78. Dowd, P. J.: Responses of the Habituated VestibuloOcular Reflex Arc to Drug Stress. USAF SAMTDR-64-72, Brooks AFB, Texas, 1964. 

79. Dowd, P. J.: Factors Affecting Vestibular Nystagmus in Coriolis Stimulation, ACTA OTOLARYNGOL. (Stockholm), 61 :228-236, 1966. 

80. Dowd, P. J., and R. L. Cramer: Habituation Transference in Coriolis Acceleration, AEROSPACE 

MED., 38:1103-1107, 1967. 

81. Dunlap, K. : Adaptation of Nystagmus to Repeated 

Caloric Stimulation in Rabbits, J. COMP. PSYCHOL., 5 :485-493, 1925. 

82. Fearing, F. S.: Post-Rotational Head Nystagmus 

in Adult Pigeons, J. COMP. PSYCHOL., 6:115-131, 

1926. 
83. Fearing, F. S.: The Retention of the Effects of 

Repeated Elicitation of the Post-Rotational Nystagmus in Pigeons. I. The Retention of the Effects 

of ":Massed" Stimulation, J. COMP. PSYCHOL., 

30:31-40, 1940. 

84. Fearing, F. S. : The Retention of the Effects of 

Repeated Elicitation of the Post-Rotational Nystagmus in Pigeons. II. The Retention of the 

Effects of "Distributed" Stimulation, J. COl\lP. 

PSYCHOL., 31 :47-56, 1941. 

85. Fearing, F. S., and 0. H. Mowrer: The Effect of 

General Anesthesia Upon the Experimental Reduction of Vestibular Nystagmus, J. GEN. PSYCHOL., 

11:133-144, 1934. 

86. Fernandez, C., and R. Schmidt: Studies on Habituation of Vestibular Reflexes. II. Effect of Caloric 

Stimulation in Decorticated Cats, ANN. OTO-, 

RHINO-, LARYNGOL., 71 :299-321, 1962. 

87. Fernandez, C., and R. Schmidt: Studies in Habituation of Vestibular Reflexes : III. A Revision, 

LARYNGOSCOPE, 72 :939-953, 1962. 

88. Fitzgerald, G., and C. S. Hall pike: Studies in 

Human Vestibular Function. I. Observations on 

the Directional Preponderance ("Nystagmusbereitschaft") of Caloric Nystagmus Resulting from 

Cerebral Lesions, BRAIN, 65:115-137, 1942. 

89. Fluur, E., and L. Eriksson : Nystagmographic Recording of Vertical Eye Movements, ACTA OTOLARYNGOL. (Stockholm), 53:486-492, 1961. 

90. Fluur, E., and L. Mendel: Habituation, Efference 

and Vestibular Interplay. I. Monaural Caloric 

Habituation, ACTA OTOLARYNGOL. (Stockholm), 

55 :65-80, 1962. 

91. Fluur, E., and L. Mendel: Habituation, Efference 

and Vestibular Interplay. II. Combined Caloric 

Habituation, ACTA OTOLARYNGOL. (Stockholm), 

55:136-144, 1962. 

92. Fluur, E., and L. Mendel: Recording of Vertical 

Rotatory Nystagmus, PRAC. OTO-, RHINO-, 

LARYNGOL., 25 :319-323, 1963. 

93. Fluur, E., and L. Mendel: Habituation, Efference 

and Vestibular Interplay. III. Unidirectional 

Rotatory Habituation, ACTA OTOLARYNGOL. 

(Stockholm), 57 :81-88, 1964. 

94. Forssman, B.: Studies on Habituation of Vestibular 

Reflexes. VII. Habituation in Light of Calorically 

Induced Nystagmus, Laterotorsion and Vertigo in 

Man, ACTA OTOLARYNGOL. (Stockholm), 57: 

163-176, 1964. 

95. Forssman, B., N. G. Henriksson, and D. A. Dolowitz: Studies on Habituation of Vestibular Reflexes. VI. Habituation in Darkness of Calorically 

Induced Nystagmn~. Laterotorsion and Vertigo in 

Man, ACTA OTOLARYNGOL. (Stockholm), 56:663-

674, 1963. 

96. Fukuda, T., M. Hinoki, and T. Tokita: Static and 

Kinetic Labyrinthine Reflex: Functional Development of Labyrinthine Function With Rotatory 

Training, ACTA OTOLARYNGOL. (Stockholm), 

49:467-477, 1958. 

33 

97. Fukuda, T., T. Tol;;:ita, S. Aoki, T. Watanabe, K. 

Hishida, K. Tashiro, H. Miyata, and U. Mazuoka: 

Study on Nystagmus During Voluntary ActsObservation of Rotation in Ballet, J. OTO-, RHINO-, 

LARYNGOL. SOC. JAP. (Supplement), 70:11-12, 

1967. 

98. Fukuda, T., T. Tokita, l\I. Hinoki, and M. Kitahara : 

The Physiology of Training the Functional Development of the Labyrinthine Function Through the· 

Daily Repetition of Rotary, Centrifugal, See-Saw 

and Pendulum-Like Motions, ACTA OTOLARYNGOL. ( Stot:I;;:holm), 56 :240-250, 1963. 

99. Gillingham, K. K.: Mental Arithmetic During 

Electron~·stagmographic Testing, ANN. OTO-, 

RHINO-, LARYNGOL., 78 :575-586, 1969. 

100. Go to, K., K. Tolmmasu, and B. Cohen : Return Eye 

Movements, Saccadic Movements, and the Quick 

Phase of Nystagmus, ACTA OTOLARYNGOL. 

(Stockholm), 65 :426-440, 1968. 

101. Graybiel, A., F. E. Guedr~·. W. H. Johnson, and 

R. Kennedy: Adaptation to Bizarre Stimulation 

of the Semicircular Canals as Indicated by the 

Oculogyral Illusion, AEROSPACE MED., 32:321-

327, 1961. 

102. Graybiel, A., and D. Hupp: The Oculogyral Illusion: A Form of Apparent Motion Which May Be 

Observed Following Stimulation of the Semicircu!ar 

Canals, J. AVIATION l\IED., 17 :3-27, 1946. 

103. Griffith, C. R.: An Experimental Study of Dizziness, 

J. EXP. PSYCHOL., 3 :89-125, 1920. 

104. Griffith, C. R.: The Cumulative Effects of Rotational Increments, ILL. STATE ACAD. SCI. 

TRANS., 13 :122-134, 1920. 

105. Griffith, C. R. : The Effect Upon the White Rat of 

Continued Bodily Rotation, AMER. NATURALIST, 

54 :524-534, 1920. 

106. Griffith, C. R.: The Organtc Effects of Repeated 

Bodily Rotation, J. EXP. PSYCHOL., 3 :15-47, 1920. 

107. Griffith, C. R.: A Note on the Persistence of the 

"Practice Effect" in Rotation Experiments, J. 

COMP. PSYCHOL., 4:137-149, 1924. 

108. Groen, J. J., and L. B. W. Jongkees: The Turning 

•rest With Small Regulable Stimuli. III. The 

Advantages of Cupulormetria Over the Classic 

Technique of Barany, J. LARYNGOL., 62 :231-235, 

1948. 

109. Groen, J. J., and L. B. W. Jongkees: The Turning 

Test With Small Regulable Stimuli. IV. The 

Cupulogram Obtained by Subjective Angle Estimation, J. LARYNGOL., 62 :236-240, 1948. 

110. Guedry, F. E.: The Effect of Visual Stimulation on 

the Duration of Post-Rotational Apparent Motion 

Effects, J. GEN. PSYCHOL., 43 :313-322, 1950. 

111. Guedry, F. E.: The Retention of Effects of 

"Massed" and "Distributed" Vestibular Stimulation 

as Indirated by the Duration of the Oculogyral 

Illusion. USNSAM Joint Project Report No. 33, 

Pensacola, Florida, 1953. 
112. Guedry, F. E.: The Transfer of Habituation to 

Rotation With Re:;pect to the Magnitude of the 

Vestibular Stimulus. USNSAM Joint Project Report No. 34, Pensacola, Florida, 1953. 

113. Guedry, F. E.: The Transfer of Habituation to 

Rotation With Respect to the Directional Aspect 

of the Vestibular Reaction. USNSAM Joint Project 

Report No. 35, Pensacola, Florida, 1953. 

114. Guedry, F. E.: Visual Control of Habituation to 

Complex Vestibular Stimulation in Man, ACTA 

OTOLARYNGOL. (Stockholm), 58:377-389, 1964. 

115. Guedry, F. E.: Habituation to Complex Vestibular 

Stimulation in Man: Transfer and Retention of 

Effects from Twelve Days of Rotation at 10 rpm, 

PERCEPT. MOT. SKILLS, Monograph Supplement 

1-V21, 459-481, 1965. 

116. Guedry, F. E.: Orientation of the Rotation-Axis 

Relative to Gravity: Its Influence on Nystagmus 

and the Sensation of Rotation, ACTA OTOLARYNGOL. (Stockholm), 60:30-48, 1965. 

117. Guedry, F. E.: Psychophysiological Studies of 

Vestibular Function. In W. D. Neff (Ed.), Contributions to Sensory Physiology, New York, Academic Press, 63-135, 1965. 

118. Guedry, F. E., and W. E. Collins: Duration of 

Angular Acceleration and Ocular Nystagmus from 

Cat and Man. II. Responses from the Lateral 

Canals to Varied Stimulus Durations, ACTA 

OTOLARYNGOL. (Stockholm), 65:257-269, 1968. 

119. Guedry, F. E., W. E. Collins, and A. Graybiel: 

Vestibular Habituation During Repetitive Complex 

Stimulation : A Study of Transfer Effects, J. APPL. 

PHYSIOL., 19 :1005-1015, 1964. 

120. Guedry, F. E., W. E. Collins, and P. L. Sheffey: 

Perceptual and Oculomotor Reactions to Interacting 

Visual and Vestibular Stimulation, PERCEPT. 

MOT. SKILLS, 12 :307-324, 1961. 

121. Guedry, F. E., and A. Graybiel: Compensatory 

Nystagmus Conditioned During Adaptation to Living in a Rotating Room, J. APPL. PHYSIOL., 

17 :39~04. 1962. 

122. Guedry, F. E., A. Graybiel, and W. E. Collins: 

Reduction of Nystagmus and Disorientation in 

Human Subjects, AEROSPACE MED., 33 :1356-

1360, 1962. 

123. Guedry, F. E., and L. S. Lauver: Vestibular Reactions During Prolonged Constant Angular Acceleration, J. APPL. PHYSIOL., 16:215-220, 1961. 

124. Guedry, F. E., and E. K. Montague: Quantitative 

Evaluation of the Vestibular Coriolis Reaction, 

AEROSPACE MED., 32:487-500, 1961. 

125. Guttich, A.: Beitrag zur Physiologie des Vestibularapparates, BElT. ZUR ANAT. PHYSIOL., 7:1-18, 

1914. 

126. Hallpike, C. S., and J. D. Hood: Fatigue and 

Adaptation of the Cupular l\Iechanism of the Human 

Horizontal Semicircular Canal: An Experimental 

Investigation, PROC. ROY. SOC. LONDON, 141B: 

542-561, 1953. 

34 

127. Halstead, W.: The Effects of Cerebellar Lesions 

Upon Habituation of Post-Rotational Nystagmus, 

CO.MP. PSYCHOL. MONOGR., 12 :1-130, 1935. 

128. Halstead, W., G. Yacorzynski, and F. Fearing: 

Further Evidence of Cerebellar Influence in the 

Habituation of After-Nystagmus in Pigeons, AMER. 

J. PHYSIOL., 120:350-355, 1937. 

129. Harris, C. S., F. E. Guedry, and A. Graybiel: 

Positional Alcohol Nystagmus in Relation to Labyrinthine Function. USNSAM-NASA Joint Report 

No. 76, Pensacola, Florida, 1962. 

130. Henderson, J. W.: Optokinetic and Other Factors 

Modifying Vestibular Nystagmus, ARCH. OPHTHAL., 37 :459-471, 1947. 

131. Henriksson, N. G., D. A. Dolowitz, and B. Forssman : Studies of Cristospinal Reflexes ( Laterotorsion): A Method for Objective Recording of 

Cristospinal Reflexes, ACTA OTOLARYNGOL. 

(Stockholm), 55:33-40, 1962. 

132. Henriksson, N. G., C. Fernandez, and R. Kohut : 

The Caloric Test in the 9at, ACTA OTOLARYNGOL. (Stockholm), 53 :21-32, 1961. 

133. Henriksson, N. G., R. Kohut, and C. Fernandez: 

Studies on Habituation of Vestibular Reflexes. I. 

Effect of Repetitive Caloric Test, ACTA OTOLARYNGOL. (Stockholm), 53 :333-349, 1961. 

134. Hernandez-Peon, R., and H. Brust-Carmona: Functional Role of Subcortical Structures in Habituation 

and Conditioning. In J. F. Delafresnaye (Ed.), 

Brain Mechanisms and Learning, Illinois, C. c. 

Thomas, 393-412, 1961. 

135. Hinchcliffe, R.: Subjective Magnitude of Induced 

Vertigo as an Index of Caloric Response, J. 

LARYNGOL., 81 :875-885, 1967. 

136. Hixon, W. C., and J. I. Niven: A Bioinstrumentation Control Center for the Human Disorientation 

Device. USNSAM-NASA Joint Report No. 79, 

Pensacola, Florida, 1963. 

137. Holsopple, J. Q.: Factors Affecting the Duration of 

Post-Rotation Nystagmus, J. COMP. PSYCHOL., 

3 :283-304, 1923. 

138. Holsopple, J. Q.: Some Effects of Duration and 

Direction of Rotation on Post-Rotation Nystagmus, 

.J. COMP. PSYCHOL., 3 :85-100, 1923. 

139. Holsopple, J. Q. : An Explanation for the Unequal 

Reductions in Post-Rotation Nystagmus Following 

Rotation Practice in Only One Direction, J. COMP. 

PSYCHOL., 4:185-193, 1924. 

140. Hood, J. D., and C. R. Pfaltz: Observations Upon 

the Effects of Repeated Stimulation Upon Rotational and Caloric Nystagmus, J. PHYSIOL. 

(London), 124 :13Q-144, 1954. 

141. Huddleston, 0. L.: The Influence of Retinal Stimuli 

Upon Labyrinthine Head-Nystagmus of Pigeons, 

AMER. J. PHYSIOL., 95 :465-472, 1930. 

142. Johner, C. H., and H. B. Perlman: Hypnosis and 

Vestibular Function, ANN. OTO-, RHINO-, LARYNGOL., 77:126-138, 1968. 
143. Johnson, D. D., and N. Torok: Habituation of 

Nystagmus and Sensation of Motion After Rotation, 

ACTA OTOLARYNGOL. (Stocl~:holm), 69:206-215, 

1970. 

144. Jongkees, L. B. W., and A. J. Philipszoon: Some 

Nystagmographical Methods for the Investigation 

of the Effect of Drugs Upon the Labyrinth, ACTA 

PHY_SIOL. PHARMACOL. NEERLANDICA, 9 :24D275, 1960. 

145. Jongkees, L. B. W., and A. J. Philipszoon: Electronystagmography, ACTA OTOLARYNGOL. (Stockholm), Supplement 189, 1-111, 1964. 

146. King, B. G.: The Influence of Repeated Rotations 

on Decerebrate and on Blinded Squabs, J. CO~IP. 

PSYCHOL., 6 :399-421, 1926. 

147. Lachman, J., L. Aarons, and J. H. Erikson: Nystagmus: A Parameter of Mental Function, PERCEPT. MOT. SKILLS, 26 :943-950, 1968. 

148. Lansberg, M. P., F. E. Guedry, and A. Graybiel: 

Effect of Changing Resultant Linear Acceleration 

Relative to the Subject on Nystagmus Generated 

by Angular Acceleration, AEROSPACE MED., 

36:456-460, 1965. 

149. Lidvall, H. F.: Vertigo and Nystagmus Responses 

to Caloric Stimuli Repeated at Short and Long 

Intervals, ACTA OTOLARYNGOL. (Stockholm), 

53 :q07-518, 1961. 

150. Lid vall, H. F.: Vertigo and Nystagmus Responses 

to Caloric Stimuli Repeated at Short Intervals, 

ACTA OTOLARYNGOL. (Stockholm), 53 :33-44, 

1961. 

151. Lidvall, H. F. : Mechanisms of Motion Sickness as 

Reflected in the Vertigo and Nystagmus Responses 

to Repeated Caloric Stimuli, ACTA OTOLARYNGOL. (Stockholm), 55:527-536, 1962. 

152. Lidvall, H. F.: Specific and Non-Specific Traits of 

Habituation in Nystagmus Responses to Caloric 

Stimuli, ACTA OTOLARYNGOL. (Stocl~:holm), 

55 :315-325, 1962. 

153. Lidvall, H. F.: Neurotic Anxiety and Vestibular 

Function as Reflected in the Vertigo and Nystagmus 

Responses to Repeated Caloric Stimuli, ACTA 

OTOLARYNGOL. (Stockholm), 56 :445-456, 1963. 

154. Loch, W. E., and H. L. Haines: Habituation to 

Caloric Vestibular Stimulation, LARYNGOSCOPE,. 

56 :43-45, 1946. 

155. Lumpkin, R. C.: Post-Rotation Nystagmus in the 

Rabbit With Head Fixed and Head Free, J. COMP. 

PSYCHOL., 7:181-185, 1927. 

156. Mahoney, J. L., W. L. Harlan, and R. G. Bickford: 

Visual and Other Factors Influencing Caloric Nystagmus in Normal Subjects, ARCH. OTOLARYNGOL., 66 :46-53, 1957. 

157. Markaryan, S. S.: Vestibular Reactions Under the 

Effect of Various Angular Accelerations. In V. V. 

Parin (Ed. in Chief), Aviation and Space Medicine, 

Moscow, Akademiya Meditzisaskikh Nauk SSSR, 

1963. . (NASA Technical Translation F-228, 305-

308, 1964.) 

35 

158. Marshall, J. E., and J. H. Brown: Visual-Arousal 

Interaction and Specificity of Nystagmic Habituation. USAMRL Report No. 688, Ft. Knox, Kentucky, 1966. 

159. Max\vell, S. S.: The Effect of Ha"bituation· on the 

Rotation-Nystagmus as Compared With the AfterNystagmus in the Rabbit, AMER. J. PHYSIOL., 

68:125-126, 1924. 

160. Maxwell, S. S., U. L. Burke, and C. Reston: The 

Effect of Repeated Rotation on the Duration of 

After-Nystagmus in the Rabbit, AMER. J. PHYSIOL., 58:432-438, 1922. 

161. Maxwell, S. S., and G. F. Pilz: On the Relation of 

Labyrinthine and Retinal Excitations in the Rabbit, 

AMER. J. PHYSIOL., 70:118-121, 1924. 

162. McCabe, B. F.: Vestibular Suppression in Figure 

Skaters, TRANS. AMER. ACAD. OPHTHAL. 

OTOLARYNGOL., 64 :264-268, 1960. 

163. McCabe, B. F., and K. Gillingham: The Mechanism 

of Vestibular Suppression, ANN. OTO-, RHINO-, 

LARYNGOL., 73 :816-828, 1964. 

164. :McLeod, M. E., and M. J. Correia: Use of Caloric 

Test in Evaluating the Effects of Gravity on 

Cupula Displacement. USNSAM-NASA Joint Report No. 94, Pensacola, Florida, 1964. 

165. :\Ieda, E. : Effetti di Repetuti Eccitamenti Rotator! 

dell Apparato Vestibulare sue Fenmonei Soggettivi 

da Combiamenta di Perizione del Capo Durant! e 

Dope la Rotazione, RIV. MED. AERONAUT., 

10 :316-323, 1947. 

166. Mertens, R. A., and W. E. Collins: Unilateral 

Caloric Habituation of Nystagmus in the Cat: 

Effects on Rotational and Bilateral Caloric Responses, ACTA OTOLARYNGOL. (Stockholm), 

64 :281-297, 1967. 

167. ~Iowrer, 0. H.: Influence of "Excitement" on the 

Duration of Post Rotational Nystagmus, ARCH. 

OTOLARYNGOL., 19 :46-54, 1934. 

168. Mowrer, 0. H.: The Modification of Vestib!llar 

Nystagmus by Means of Repeated Elicitation, 

COMP. PSYCHOL. MONOG., 9(45) :1-48, 1934. 

169. Mowrer, 0. H.: Some Neglected Factors Which 

Influence the Duration of Post-Rotational Nystagmus, ACTA OTOLARYNGOL. (Stockholm), 22 :1-

23, 1935. 

170. Mowrer, 0. H.: The Influence of Vision During 

Bodily Rotation Upon the Duration of Post-Rotational Vestibular Nystagmus, ACTA OTOLARYNGOL. (Stockholm), 25 :351-364, 1937. 

171. Niven, J. I., W. E. Hixson, and M. J. Correia: 

Elicitation of Horizontal Nystagmus by Periodic 

Linear Acceleration, ACTA OTOLARYNGOL. 

(Stockholm), 62 :429-441, 1966. 

172. Orlov, I. V.: Thresholds of Caloric Nystagmus 

During Rotation at Constant Velocity, PROC. 

ACAD. SCI. USSR, 156 :972-975, 1964. 

173. Ornitz, FJ. M.: Vestibular Dysfunction in Schizophrenia and Childhood Autism, COMP. PSYCHIAT., 

11:159-173, 1970. 
174. Osterhammel, P., K. Terkildsen, and K. Zilstorff: 

Vestibular Habituation in Ballet Dancers, ACTA 

OTOLARYNGOL. (Stockholm), 66:221-228, 1968. 

175. Owada, K., and K. Okubu: The Otolithic Reaction 

on Nystagmus by Caloric Stimulations. In Japan 

Society of Vestibular Research: Contribution to 

the Vestibular Physiology and Vestibular Test, 

ACTA OTOLARYNGOL. (Stoci{holm), Supplement 

179, 1-6, 1963. 

176. Pendleton, M. E., and R. S. Paine: Vestibular 

Nystagmus in Newborn Infants, NEUROLOGY, 

11 :45o-458, 1961. 

177. Pfaltz, C. R., and S. V. Arx: Zur Wirkung Wiederholter Thermischer und Rotatorischer Reize auf 

das Normale Vestibulare Endorgan, ACTA OTOLARYNGOL. (Stockholm), 63:191-207, 1967. 

178. Pialoux, P., J. Gibert, P. Blanc, Ch. Chouard, and 

P. Fontelle: Study on Vestibular Habituation 

Among Pilots and Flying Staff in Terms of Their 

Training and Seniority, ADV. OTO-RHINOLARYNGOL., 17:167-168, 1970. 

179. Pilz, G. F.: On the Relation of the After-Nystagmus 

to Rotation Nystagmus. I. Direct Effects of Rotations, AMER. J. PHYSIOL., 77 :428-442, 1926. 

180. Pilz, G. F.: On the Relation of After-Nystagmus 

to Rotation Nystagmus. II. Modifying Influences, 

AMER. J. PHYSIOL., 77 :443-458, 1926. 

181. Pollack, M., and H. P. Krieger: Oculomotor and 

Postural Patterns in Schizophrenic Children, ARCH. 

NEUROL. PSYCHIAT., 79 :720-726, 1958. 

182. Preber, L.: Vegetative Reactions in Caloric and 

Rotatory Tests, ACTA OTOLARYNGOL. (Stockholm), Supplement 144, 1-119, 1958. 

183. Prince, A. L. : Observations on the Physiology of 

the Otic Labyrinth. The Influence of Prolonged 

Rotation on the Duration of Post-Rotatory· Nystagmus, PROC. SOC. EXPER. BIOL. MED., 17:202-

203, 1920. 

184. Proctor, L. R., and C. Fernandez: Studies on 

Habituation of Vestibular Reflexes. IV. Effect of 

Caloric Stimulation in Blindfolded Cats, ACTA 

OTOLARYNGOL. (Stockholm), 56:500-508, 1963. 

185. Ratner, S. C. : Annelids and Learning: A Critical 

Review. In W. C. Corning and S. C. Ratner (Eds.), 

Chemistry of Learning, New York, Plenium Press, 

391-406, 1967. 

186. Riesco-Mac-Clure, J. S. : Caloric Tests: Methods 

and Interpretation, ANN. OTO-, RHINO-, LARYNGOL. 73 :829-837, 1964. 

187. Ritvo, E. R., E. M. Ornitz, A. Eviatar, C. H. Markham, M. B. Brown, and A. Mason : Decreased PostRotatory Nystagmus in Early Infantile Autism, 

NEUROLOGY, 19 :653-658, 1969. 

188. Rossberg, G. : Regulation, Leistungsfahigkeit und 

Trainierbarkeit des Vestibularissystems, PRACT. 

OTO-RHINO-LARYNGOL., 33 :278-288, 1971. 

189. Ruppert, J.: Untersuchungen uber den Drehnystagmus, ZBL. "INN. MED., 27 :465-478, 1906. 

36 

190. Schroeder, D. J.: Influence of Alcohol on Vestibular 

Responses to Angular Acceleration, AEROSPACE 

MED., 42 :959-970, 1971. 

191. Schroeder, D. J.: Some Effects of Alcohol on Nystagmus and "Vertigo" During Caloric and Optokinetic Stimulation, ANN. OTO-, RHINO-, LARYNGOL., 81:218-230, 1972. 

192. Sokolovski, A. : Factors Influencing Nystagmus Due 

to Rotation in Normal Subjects, J. LARYNGOL., 

77 :185-201, 1963. 

193. Stahle, J.: Electronystagmography in the Caloric 

Test, ACTA SOC. MED. UPSAL., 61 :307-332, 1957. 

194. Suzuki, J., and G. Totsuka: Post Rotatory Nystagmus: Modifications Observed in Experiments With 

Repeated Rotatory Stimulation, ACTA OTOLARYNGOL. (Stockholm), 51 :570-578, 1960. 

195. Thorpe, W. H. : The Concepts of Learning and 

Their Relation to Those of Instinct. In Syrup. Soc. 

Exp. Bioi. : Physiological Mechanisms in Animal 

Behavior, Cambridge, Cambridge University Press, 

387-408, 1950. 

193. Tokita, T., S. Aoki, T. Watanabe, and H. Miyata: 

Telemetering of Eye and Head Movements in Ballet 

Rotation, EQUILIBRIUM RES. (Japan), Sup. 

1 :49-59, 1971. 

197. Torok, N.: Nystagmus Frequency Versus Slow 

Phase Velocity in Rotatory and Caloric Nystagmus, 

ANN. OTO-, RHINO-, LARYNGOL., 78:625-639, 

1969. 

198. Torok, N. : The EffeCts of Arousal Upon Vestibular 

Nystagmus, ADV. OTO-RHINO-LARYNGOL., 17:76-

89, 1970. 

199. Tsch!assny, K.: Perrotatory Nystagmus in the 

Ballet Dancer, Pigeon, and Blind Person, ANN. 

OTO-, RHINO-, LARYNGOL., 66 :641-648, 1957. 

200. Vogelsang, C. J.: The Perception of a Visual Object 

During Stimulation of the Vestibular System, ACTA 

OTOLARYNGOL. (Stockholm), 53:461-469, 1961. 

201. Wendt, G. R.: An Interpretation of Inhibition of 

Conditioned Reflexes as Competition Between Reaction Systems, PSYCHOL. REV., 43 :258-281, 1936. 

202. Wendt, G. R.: Vestibular Functions. In S. S. 

Stevens (Ed.), Handbook of Experimental Psychology, New York, Wiley, 1191-1223_, 19fil. 

203. Wendt, G. R.: The Nature of Adaptation to Oscillatory Rotation. In The Role of the Vestibular 

Organs in the Exploration of Space. NASA Report 

SP-77, NASA, Washington, D.C., 133-139, 1965. 

204. Winget, C. M., and A. H. Smith: Quantitative 

Measurement of the Labyrinthine Function in the 

Fowl by Nystagmography, J. APPL. PHYSIOL., 

17 :712-718, 1962. 

205. Winget, C. M., A. H. Smith, and C. F. Kelly: 

Effects of Chronic Acceleration on Induced Nystagmus in the Fowl, J. APPL. PHYSIOL., 17:709-711, 

1962. 

206. Wit, G. de: Seasickness (Motion Sickness): A 

Labyrinthological Study, ACTA OTOLARYNGOL. 

(Stockholm), Supplement 108, 1-56, 1953. 
207. Wolfe, J. W.: Evidence for Control of Nystagmic 

Habituation by Folium-Tuber Vermis and Fastigial 

Nuclei, ACTA OTOLARYXGOL. (Stockholm), Supplement 231, 1-48, 1968. 

208. Young, L. R. : Measuring Eye Movements, AMER. 

J. MED. ELECTRON., 2 :300-307, 1963. 

3'7 

209, Yuganov, Y. M.: The Problem of Functional Characteristics and Interaction of the Otolithic and 

Cupular Portions of the Vestibular Apparatus 

Under ConditiQlls of Altered Gravity. In N, M. 

Sisakyan (Ed. in Chief), Problems of Space Bwlogy, 

Vol. 4, Moscow, lzd-vo Akademii Nauk SSSR, 1965. 

(NASA Technical Translation F-368, 48-63, 1966.)