AM 67-2 

ADAPTATION TO VESTIBULAR DISORIENTATION. IV. 

Responses to Angular Acceleration and to Bilateral Caloric Stimulation 

Following Unilateral Caloric Habituation 

Approved by 

~~ J. R. DILLE, M.D. 

CHIEF, CiviL AEROMEDICAL 

INSTITUTE 

Ruth Ann Mertens 

and 

William E. Collins 

January 1967 

Released by 

P. v. SIEGEL, M.D. 

FEDERAL Am SuRGEON 

FEDERAL AVIATION AGENCY 

Office of Aviation Medicine 
Qualified requestors may obtain Aviation Medical Reports from Defense Documentation 

Center. The general public may purchase from Clearinghouse for Federal Scientific and 

Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151 
ADAPTATION TO VESTIBULAR DISORIENTATION. IV. 

Responses to Angular Acceleration and to Bi1ateral Caloric Stimulation 

Following Uni1ateral Caloric Habituation 

I. Introduction 

Thorpe14 defines ha:bitmation as "an activity of 

the centra:l nervous system whereby innate responses to certain relatively simple stimuli, especially those of ·potential value as warning of 

danger, wane as the stimuli continue for a long 

period without unfavourable results"; hrubituation, then, is learning not to respond. In accordance with this central concept of habituation, it 

has been suggested that the response declines to 

repeated vestibular stimulation are forms of 

learning, as they evidence the characteristics of 

learned beha vior~acquisition, retention, and 

transfer. 

Several recent investigations have been concerned with questions of transfer-effects in 

habituation of ocular nystagmus. One such effect 

is that of stimulus transfer, i.e., transfer of 

habituation from one type of stimulation (e.g., 

rotatory) to another (e.g., caloric). 

MaX'well, Burke, and Reston13 and Hood and 

Pfaltz12 reported no decline in nystagmic re-

~ponses to caloric stimuli after rotatory habituttion. More recently, Collins2•

3 investigated 

bransfer from rotatory to caloric and from caloric 

;o rotatory situations and obtained minimal transfer. Dunl3)p8, however, found a marked reduction 

:n the response of rll)bbits to rotatory stimulation 

rollowing a series of caloric irrigations with ice 

;vater. The absence of stimulus transfer-effects2•

3 

1as been attributed t'o (1) differences in intensity 

>f response produced by caloric irrigation and by 

mgular acceleration; ( 2) differences in the pat-

:ern of neural excitation to unilateral and to biateral stimulation. A study by Capps and Colins1 isolated certain of these differences and 

:howed that, irrespective of the stimulus intensiA major portion of the data presented here was submitted 

y the first-named author to the Psychology Department, Uniersity of Oklahoma, in partial fulfillment of the requirements 

or the degree of Master of Science. Grateful acknowledgment 

l made of the assistance rendered by Bill Updegraff, Sue 

frounds, Nancy Rice, Jeanne Heaton, and David Schroeder. 

1 

ties used, . a significant reduction in nystagmic 

responses of the cat to unilateral stimulation 

occurred after habituation to bilateral caloric 

irrigations. The present study was designed to 

examine furtJher some questions regarding transfer of hrubituation while attempting to evaluate 

the influences of intensity, type of stimulus, and 

unilateral vs. bilateral stimulation. 

II. Methods 

Subjects and Restraint. Subjects were 60 mature cats, unused in previous experiments, and 

assigned randomly to six equal groups. Restraint 

was accomplished by the method of Henriksson, 

Fernandez, and Kohut11 with an adjustll)ble restraining device. For rotation trials, the head 

was positioned so that a line from the outer 

canthus of the eye to the tragus of the ear was in 

the horizontal plane, placing the la·teral canals in 

the plane of rotation; for cah>ric irrigations, the 

head was inclined 45° upward from the horizontal. 

Oalorization. Water baths equipped with 

Bronwill constant temperature circulators were 

used for 26°0, 30°0, and 46°C stimuli. For ice 

water irrigations temperature was 4°0. Rubber 

tubing extended from the wa'ter baths to irrigation nozzles which were inserted into the animal's 

ears. Rate of water flow was 15ccjsec. Irrigation periods were controlled automatica:lly by 

means of solenoids connected to a Hunter Interval 

Timer, Model 1'1;1.-C. 

Rotation. The turntable5 was situated in a 

light-proof room. A set of tiers allowed as many 

as three cats to be rotated simultaneously with 

their heads at the center of rotation6• 

Recording. Needle electrodes inserted at the 

outer canl:!hi of the cats' eyes picked up corneoretinal potentials, which were relayed through a 

terminal electrode board to the recorder. Two 
Offner recorders were used, a Type TC for caloric 

trials and a Type R for rotation trials. A 3-sec 

time constant was employed in amplification. 

0 alibration. Prior to vestibular testing, eye 

movement calibratiDns were obtained by means 

of an optokinetic stimulator (a steel drum with 

a striped interior). Eye movements (optokinetic 

nystagmus) induced by rotation of the drum at 

24° jsec were recorded, measured, and used to 

cal'culate calibration constants. 

Sooring. For all trials, three types of measures were obtained : amount of slowphase eye 

displacement (in millimeters), number of nystagmic beats (frequency), and duration of response 

(in seconds). Slowphase displacement values in 

millimeters were transformed into degrees of eye 

movement by means of the calibration constants1 • 

III. Procedure 

Six groups of animals were used. A different 

series of 15 habituation trials was administered 

to each of five of these groups; t'he sixth group 

received no h!llbituation trials (see Table 1). All 

animals were given identical pre- and post-tests 

(bilateral caloric irrigations and rotation trials). 

All trials, irrcluding the irrigation periods, were 

in total darkness. 

PRE- AND POST-TESTS 

For all animals, the pre- and post-test rotation 

trials consisted of an acceleration (5° jsec2 for 12 

sec), 2 min of constant velocity, and a subsequent 

deceleration (5° jsec2 for 12 sec) ; half of the subjects in each group received 'Clockwise rotations 

and the remaining half received counterclockwise 

rotations. Pre- and post-test bilateral caloric 

stimulation consisted of simultaneous irrigations 

with water at a temperature of 30°C to the right 

ear and 46°C to the left ear. Duration of stimulation was 20 sec. 

HABITUATION TRIALS 

Experimental Groups. The habituation series 

for the three experimental groups consisted of 15 

unilateral irrigations. 

Experimental Group I received an habituation 

series of ice water irrigations ( 4°C) applied to 

the right ear ·for 15 sec. The habituati'On trials 

for this group were of a greater intensity (resulted in greater response output) rela·tive to the 

pre-trials than those of the other two experimental groups. 

Experimental Group II received habituation 

trials consisting of irrigations with 26°C water, 

TABLE 1. Schedule of Test Stimuli for Each Group. (R=right ear; L=left ear; 

rw =ice water irrigation; all temperatures are in ( °Centigrade) 

Pre-1 

Rotation 

(5° jsec2 for 12 sec 

accel and decel) 

Control Groups 

Oalorio. Bilateral Caloric 

(R30°L46°C for 20 sec) 

Rotation. Rotation 

(5° jsec2 for 12 sec accel; 

subthreshold decel) 

P'l'e-tests 

Habituation Series 

0 ombined. No habituation trials 

Post-1 

Bilateral Caloric 

(R30°L46°C for 20 sec) 

Post-tests 

2 

Pre--2 

Bilateral Caloric 

(R30°L46°C for 20 sec) 

Ell!perimental Groups 

I. Unilateral Caloric 

( IW right for 15 sec) 

II. Unil!llteral Caloric 

(R26°C for 30 sec) 

II I. Unilateral Oaloric 

(R30°C for 30 sec) 

Post-re 

Rotation 

(5° jsec2 for 12 sec 

accel and decel) 
administered to the right ear for 30 sec. These 

trials were of an intensity intermediate to those 

received by Groups I and III. 

Experimental Group III received an habituation series of irrigakions with 30°C water applied 

to the right ear :for 30 sec. This hwbituation 

s.eries was the least intense of those received by 

the experimental groups. 

Control Groups. Three control groups were 

used to provide a measure of the expected level 

of response after 15 bilateral calorizations ( Caloric Oontrol), 15 rotation trials (Rotation Control), and a period of no stimulation (Combined 

Control). 

The Caloric Control Group received an habituation series o:f bilateral irrigations ( 30°C water 

to ·the right ear and 46°C to the left ear simultaneously for 20 sec). These 15 habituation trials 

were identical to the pre- and post-test bilateral 

irrigations received by all groups. 

The Rotation Control Group received habituaGion trials which consisted of counterclockwise 

accelerations (5° jsec2 for 12 sec), 2 min of con-

~tant velocity, and subthreshold decelerations 

(0.15° jsec2 ). Thus, only eye movements in the 

~arne direction as those evoked by the caloric 

habituat~on trials were elicited. 

The Combined Control Group received no 

hrubituation trials. The animals remained in regtraint for a period of time equal to that of an 

hil:bituation series. 

The test schedule appears in Table 1. In all 

3ases a time interval of 20 minutes between the 

~tart o:f successive trials was provided. Animals 

were run in groups of £our :for the caloric trials 

md in groups o:f three :for rotation trials whenwer practicable. All animals were in room 

lllumination for at least five minutes prior to 

each trial. 

IV. Results 

HABITUATION TRIALS 

Experimental Groups. All experimental groups 

widenced response declines :from Trial 1 to Trial 

L5 of the habituation series. These reductions 

ranged :from 76-83% :for slowphase displacement, 

from 58-74% for beat-frequency, and :fr~m 15-

36% for duration of response. Response reducGion was most marked during the early trials of 

Ghe habituation series. 

The three stimulus levels (ice water, 26°C, and 

l0°C) produced the expected variation in re3 

sponse. Ice water evoked the greatest amount 

o:f nystagmus, the 30°C irrigations produced the 

least, while the 26°C stimulus yielded an intermediate level o:f response. 

Control Groups. Both the Caloric and the 

Rotation Controls exhi'bited declines :from Trial 

1 to Trial 15 of the habituation series. (The 

Combined Control Group received no habituation 

trials.) The Caloric Control response decline 

was 62% for slowphase displacement, 50% for 

number of beats, and 2% for duration of response. Corresponding reductions for the Rotation Oon'trol Group· were 45%, 23%, and 15%, 

respectively. 

PRE- AND POST-TEST TRIALS 

Group Differerwes. For the six groups, analyses of covariance were conducted on pre- and 

post-test scores for (1) the bila·teral calorie tests, 

(2) the rotatory stimuli eliciting responses in the 

direction stimulated during the habituation series, 

and ( 3) the rotatory stimuli eliciting responses 

in the direction opposite to that stimulated during 

the habituation trials. Separate analyses were 

executed for the three measures o:f nystagmus 

(slowphase, :frequency, and duration). (1) 

Groups differed in pre- to post-test response decline for !bilateral calorizations on all measures 

( .001 levels) . ( 2) For responses to rotation in 

the same direction as those elicited during the 

habituation trials, the groups also evidenced significant differen(les in pre- to post-test response 

reduction on all measures ( .05 to .01 levels). 

( 3) No significant differences in pre- to post-test 

response declines were :found :for responses to 

rotation in the direction opposite to those which 

oecurred during the 'habituation series. 

To ascertain which groups differed significantly 

in pre- to post-test response decline, t tests were 

executed on group pre- to post-test difference 

scores (% decline) . 

Bilateral Calorizations. For bilateral caloric 

data, declines ro:f the various groups were evaluated by comparing them statistically with the 

declines shown after a bilateral caloric habituation series (the Caloric Control Group) and with 

the reductions evidenced after a period of no 

stimulation (the Combined Control Group). For 

slowphase displacement, frequency, and duration 

o:f response resulting ·:from bilateral caloric stimulation, the response declines of the three experi-
mental groups were as great as those of the 

Caloric Control Group. The three experimental 

groups and the Caloric Control Group also had 

significantly greater reductions in out·put on all 

measures than did both tihe Comlbined and the 

Rotrution Control Groups ( .05 to .001 levels) , 

while the latter two groups did not differ from 

each other on any measure. Thus, unilateral 

ha:bituation stimuli produced as great a bilateralcaloric response reduction as did a series of bilateral caloric irrigations : that is, unilateral 

caloric habituation transferred to bilateral caloric 

stimulation. 

The response reductions among experimental 

groups were not found to differ significantly on 

any measure. Thus, intensity of the habituating 

stimulus did not appear to he a significant variable in this transfer of habituation. 

The Rotation Control Group showed significantly less ·pre- to post-test caloric response decline than did the three experimental groups and 

the Caloric Control Group (.05 to .001 levels), 

while exhibiting a reduction no greater than that 

of the Combined Control Group (the group receiving no habituation stimulation). Therefore, 

it would seem that rotatory habituation did not 

transfer to bilateral caloric stimulation, although 

both stimuli •were of a bilateral nature. 

Figure 1 illustrates tJhe group reductions in 

responses to the bilateral caloric irrigations for 

the experimental and control groups. Tracings 

of nystagmus during pre- and post-test bilateral 

caloric responses are presented in Figure 2 for 

the experimental groups and in Figure 3 for the 

control groups. 

Angular Accelerations: Responses in the Direction Elicited During Habituation. For rotation-induced responses in the same direction as 

those elicited during the habituation series, preto post-test changes shown by the groups were 

evaluated by comparing them with the declines 

round a:fter a rot.atory habituation series (the 

Rotation Control Group) and with the changes 

shown by the Combined Control Group. The 

Rotation Control Group declined significantly 

more in slowphase output than did all other 

groups ( .05 to .001 levels). (The Combined 

Control Group also declined significantly more 

than Experimental Group III.) For beatfrequency in the habituated direction, the response reduction of the Rotation Control Group 

4 

was statistically greater than that of only Experimental Group III ( .05 level) . (Group III also 

declined significantly less than did Groups I and 

II.) The fact that the Rotation Control Group 

did not exhi!bit a greater mean decline in beat 

frequency was due to a large pre- to . post-test 

increase in the number of eye movements from 

one animal; the ·post-test response consisting of 

a large number o·f low-amplitude nystagmic beats. 

The decline in duration of response for the Rotation Oontrol Group was not statistically greater 

than that for any of the other groups. (Experimental Group I showed a significantly greater 

reduction in duration of response than did Experimental Group III or the Combined Control 

Group.) Thus, frequency and duration data allow for no unequivocal conclusion concerning 

caloric-to-rotatory transfer, as the decline of the 

Rotation Control Group on these measures was 

statistically no greater than that shown by the 

group receiving no habituation trials (the Combined Control Group). On the 'basis of the slowphase data dbtained, however, it would appear 

that habituation to caloric stimulation has little 

effect on rotatory responses. 

Figures 4 and 5 demonstrate pre- to post-test 

reductions for rotation responses in both directions for the experimental and control groups, 

respectively. 

V. Discussion 

TRANSFER OF UNILATERAL CALORIC 

HABITUATION TO BILATERAL CALORIC 

STIMULATION 

The data indicate that unilateral caloric habituation transfers to bilateral caloric stimulation. 

All three experimental groups (those groups receiving unilateral caloric habituation trials)' 

exhibited as great a bilateral-caloric response 

reduction as did the Caloric Control Group (the 

group receiving bilateral caloric habituation 

trials). 

While the three intensities of unilateral stimuli 

resulted in three different levels of responseoutput on early trials, the intensity factor did 

not appear to influence transfer of unilateral 

habituation to bilateral stimulation, within the 

intensity limits described here, as the three experimental groups did not differ in amount of 

post-test bilateral-caloric response reduction. 

This finding parallels that of Capps and Collins1 
who indicated that intensity of the habituating 

stimulus was a negligible factor in their examination of bilateral~to-unilateral transfer of caloric 

ha!bituation. 

TRANSFER OF CALORIC HABITUATION 

TO ROTATORY .STIMULATION 

All groups receiving caloric habituation trials 

(the three ex·perimental groups and the Caloric 

Control Group) evidenced significantly smaller 

reductions in pre- to post-test slowphase displacement responses to rotation in the habituated 

direction than did the Rotation Control Group. 

For slowphase displacement, the Rotation Control Group also showed a greater response reduction than did the Combined Control Group. This 

was not the case for reductions in beat frequency 

and duration of response, however. The unexpectedly small mean decline in beat frequency 

evidenced by the Rotation Control Group ( significant'ly greater than the decline of only one 

other group) was due, as noted earlier, to depression of the mean by an atypical pre- to posttest increase, ·for this measure only, shown by 

one animal in tJhe group (this same animal 

showed a 25% pre- to post-test reduction in 

slowphase displacement). 

The values plotted in Figures 4 and 5 indicate 

that all groups which received caloric ha!bituation 

trials (the three experimental groups and the 

Caloric Control Group) exhibited somewhat 

greater reductions ·for frequency and duration 

scores during ·post-test rotations which elicited 

nystagmus in the same direction as that elicited 

during the caloric habituation trials (as opposed 

to rotation-induced nystagmus in the direction 

opposite to that stimulated during the habituation series). This suggests that the caloric 

habituation series may have exerted some influence on subsequent responses to angular Mceleration. On the basis of these data, then, it is 

suggested that while caloric stimulation may 

have some influence on responses to rotation, a 

series of caloric irrigations apparently does not 

produce nearly so great a response reduction as 

does an equa'l number of rotation trials, even 

though the caloric stimuli are of much greater 

intensity ('produce a greater response output) 

than the angular stimuli. That this is the case 

whether the caloric stimuli employed activate 

only one la!byrinth (the three experimental 

groups) or both la!byrinths (the Caloric Control 

5 

Group) indicates that differences in caloric and 

rotatory modes of activation may he at least 

partially responsible for failure to dbtain transfer. Another possible explanation for lack of 

intermodal transfer lies in the difference between 

position of the otoliths during rotatory and during caloric stimulation (heads were fixed in a 

position approximately that of normal carriage 

for rotation trials and were eleva;ted 4'5° for 

caloric irrigation). To the extent that the otoliths might influence semi-circular canal responses, transfer of nystagmus habituation might 

be specific to a given position of the otoliths. 

Data presented below in tJhe section dealing with 

rotatory-to-caloric transfer of habituation appear 

to support either of the possible explanations 

offered above. 

TRANSFER OF ROTATORY 

HABITUATION TO BILATERAL 

CALORIC STIMULATION 

Results of the present investigation demonstrate a failure to obtain transfer of response 

declines from rotatory ha:bituation to bilateral 

caloric stimulation. This is readily apparent in 

the values plotted ·for the Rotation Control Group 

in Figure ·1. ·. That no significant rotatory-tocaloric transfer was obtained is in agreement 

with findings of other investigators3•

12•

18• 

The failure to dbtain transfer, however, cannot 

be ascribed to differential stimulation of one or 

botJh lrubyrinths by the rotatory and caloric stimuli, as the caloric irrigations used in the transfer 

tests were bila;teral. 'A'lso, data already reported1 , 

as well as findings of this study, indicate that 

intensity of the habituating stimulus appears to 

be a negligrble :factor in transfer of habituation 

within the intensity limits employed. Specifically, in the present investigation, caloric irrigations (both unilateral and bilateral), although 

of a greater intensity than the angular stimuli 

used, appeared to have only a slight effect on 

responses to rotation. In addition, intensity of 

the habituating stimuli was :found not to influence unilateral-to-bilateral caloric transfer of 

ha;bituation. The present lack of transfer, therefore, cannot be explained adequately as being a 

result of the fact that the rotation trials (habitua:tion series) were relatively mild stimuli in comparison to the pre- and post-test bilateral caloric 

irrigations. It would seem, then, that failure to 

dbtain rotatory-to-caloric transfer may depend 
more upon differences in the rotatory and caloric 

modes of response-activation or upon some otolithic influence than upon relative intensities or 

differential stimul'a.tion of the labyrinths. 

ADDITIONAL OBSERVATIONS 

Sew Differences. Capps and Collins1 reported 

statistically significant ( .05 level) sex differences 

(favoring female cats) in amount of slowphase 

output and frequency of nystagmus to unilateral 

irrigations. The 22 male cats in this study were 

compared by t test with a group of 22 female 

cats randomly selected from the remainder of 

the group. Although females were found to 

have greater average pre-test response output 

to bilateral caloric irrigation than did males 

(2978° vs. 1842° for slowphase displacement; 

175 vs. 121 for frequency), these differences fell 

just short of statistical significance at the .05 

level (t = 1.99 and 1.87 where p.os = 2.02). 

Female cats also showed slightly greater average 

responses to the pre-test rotation (673° vs. 610° 

for slowphase displacement; 33 vs. 32 for frequency), but these differences were clearly not 

significant ( t = 0:71 and 0.49 where p.os = 2.02). 

The present findings thus indicate that if sex 

differences in vestibular functioning of the cat 

exist (a) they are probrubly limited to caloric 

stimulation and related more to ·physical factors 

influencing thermal conduction than to vestibular 

function per se, and (tb) there is considerable 

overlapping of the male and female response 

distributions. 

Double irrigations. When water of t:he same 

temperature is applied to both ears simultaneously (double irrigations), the opposing stimuli 

theoretically cancel any horizontal nystagmus4 • 

Upon administering double irrigations to a group 

of cats already habituated to unidirectional bilateral calorizations, Capps and Collins1 found 

no effect o£ the habituation series on responses. 

To examine further the possible influence of unidirectional caloric habituation on responses to 

double irrigations, animals in Experimental 

Group II (26°C) and the Combined Control 

Group (no habituation stimulation) were administered •two double irrigations immediately following the post-2 trial. Half of the animals 

received stimulation with water of 30°C on the 

first trial and 46°C on the second trial. The 

order was reversed for the remaining animals. 

6 

Some clearly-defined nystagmus was Obtained 

on 6 of 20 records from the Combined Control 

Group and on 11 of 20 for Experimental Group 

II. For the Combined Control Group, 3 records 

evidenced nystagmus in the "unhabituated" direction, 1 in the "habituated" direction, and 2 

showed "reversing" responses (responses first in 

the unha:bituated direction and then in the habituated direction). For Experimental Group II, 

8 records yielded responses in the unhahituated 

direction, 2 were in the habituated direction, and 

1 case of "reversing" occurred. Seven of the 

eight responses in the habituated direction were 

accounted for by four cats. Thus, although animals exposed to an habituation series produced 

more tracings witJh some clear nystagmus than 

did animals receiving no habituation stimulation, 

data of the present study offer no unequivocal 

evidence that unilateral caloric habituation influences responses to "double irrigations". 

Additional post-trials. A single post-test for 

transfer may not always be sufficient to allow 

habituation transfer-effects to evidence themselves1. In order to explore this poss~bility, the 

Rotation Control Group was given a series of 

eight bilateral caloric irrigations after completion 

of the post-2 rotation trial. These consisted of 

four trials during which responses were elicited 

in the habituated direction (R30°L46°) and four 

trials during which responses in the unhabituated 

direction (R46°L30°) were evoked. The two 

stimuli were applied alternately from trial to 

trial ; irrigation periods were 20 sec. In addition, 

the Caloric Control Group was given a series of 

five r<Jtation trials following (and identical to) 

the post-2 trial. Half of the animals were rotated CW and half were rotated OCW. 

As can he seen in Figure 6, responses in both 

the habituated and unhabituated direotions £all 

off to about the same level after four irrigations 

or after five rotations (taking into consideration 

the pre- and post-test trials) . This provides 

confirmati-on that rotatory habituation trials had 

little influence on responses to caloric irrigation 

and that bilateral caloric habituation had little 

effect on rotation-induced responses. Transfereffects, therefore, were not merely "masked" by 

such factors as novelty due to a change of the 

stimulus. 

Retention Trials. Repor:ts indicate that habituation of nystagmus is retained for consider-
a:ble periods of time1 • 11 • In order to dbtain some 

further information regarding retention, half of 

the animals in Experimental Groups I (ice water) 

and III (30°C) were tested at one week following, and the remaining half at one month following, their habitua:tion series. Eight bilateral 

caloric irrigations were administered at rates of 

15ccjsec for 20 sec. Four irrigations produced 

responses in the direction previously habituated 

(R30°L46°), and four yielded nystagmus in the 

opposite direction (R46°L30°). The two stimuli 

were alternated from trial to trial. 

Data obtained after one week and after one 

month of rest are plotted in Figure 7. As data 

for Groups I and III were similar, results were 

combined. One week after the habituation series, 

the first test in the habituated direction showed 

recovery to 60% of the original pre-test level. 

The "one-month" retention curves indicate more 

recovery (75% of the pre-test), but drop off more 

rapidly than the "one-week" retention curves. 

Urrhabituated-direction slowphase responses at 

one month also decline more ra:pidly than at one 

week, reaching 30% of pre-test after 4 trials. 

Initial differences between the response curves 

for the habituated and unhabituated directions 

indicate the directional specificity of habituation. 

However, responses in both directions declined 

steadily with repeated stimulation. These cat 

data do not agree with the views offered by Fluur 

and Mendel9 • 10, based on human subjects, indicating that no habituation occurs if nystagmus 

is elicited alternately in opposite directions4 • 6 • 

VI. Summary 

Transfer of nystagmus habituation from unilateral calorization and from unidirectional rotation to bilateral calorization and to bidirectional 

rotation was investigated in 60 subjects. Reductions in bilateral caloric responses were ·dbtained 

independent of the intensity of the unilateral 

caloric habituating stimuli. Habituation to rotatory stimulation was found to have no effect 

on responses to bilateral · caloric irrigations. 

Caloric habituation appeared to exert relatively 

little influence on rotation responses. Additional 

observations were concerned with retention of 

habituation, possible sex differences in nystagmic 

output, "double irrigations", and the influence of 

several post-tests on nystagmic responses in the 

unhabituated direction. 

REFERENCES 

1. CAPPS, M. J., and CoLLINS, W. E., 1965 : Effects of 

bilateral caloric habituation on vestibular nystagmus 

in the cat. Acta Otolaryng. (Stockh.), 59, 511-530. 

2. CoLLINs, W. E., 1964 a : Nystagmus responses of the 

cat to rotation and to directionally equivalent and 

non-equivalent stimuli after unilateral caloric 

habituation. Acta Otolat·yng, ( Stockh.), 58, 247-258. 

3. CoLLINS, W. E., 1964 b : Primary, secondary, and 

caloric nystagmus of the cat following habituation 

to rotation. J. Oomp. Physiol. Psychol., 51, 417-421. 

4. CoLLINS, W. E., 1965: Effects of "double irrigations" on the caloric nystagmus of the cat. Acta Otolaryng. 

( Stockh.), 59, 45-54. 

5. CoLLINs, W. E., and HuFFMAN, W. H., 1964: Design 

and performance characteristics of a mechanically 

driven vestibular stimulator. CARl Report No. 64-15, 

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dog. Acta Otolaryng. ( Stockh.), 62, 19-26. 

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8. DUNLAP, L., 1925: Adaptation of nystagmus to repeated caloric stimulation in rabbits. J. Oomp. 

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9. FLUUR, E., and MENDEL, L., 1962 a: Habituation, 

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1961: The caloric test in the cat. Acta Otolaryng. 

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12. HOOD, J. D., and PFALTZ, C. R., 1954: Observations 

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13. MAXWELL, S. S., BURKE, U. L., and RESTON, C., 1922: 

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after-nystagmus in the rabbit. Amer. J. Physiol., 58, 

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1- (/) 

en z 0 

ILl 90 ILl 90 z 90 ILl ::!: 0 

1- lr ILl 0 C) > ILl (/) ILl 80 0 80 • (/) 80 ILl 0 ::!: 1- 3!:: ILl • ILl (/) 70 >- 70 (/) 70 0:: :::::> ILl :::::> 

a.. ::!: 0 ::!: C) C) 

lL. ~ 60 ~ 60 ~ 60 0 C) Control Groups: (/) 

~ (/) 

>- >- Caloric ·-· 1- z (/) z z 50 >- 50 50 

ILl ILl z IL. Rotation •-• 

u (/) 0 <{ IL. Combined_ o-o 0:: I 40 0 40 z 40 ILl Q. .:> a.. lr 

~ Stimulus: 3: ILl 

ID 0 30 ::!: 30 lr .J 30 Bilateral Caloric :::::> (/) :::::> 0 z R30•c: L46•c 

20 20 20 for 20sec 

10 10 10 

0 0 0 

PRE POST PRE POST PRE POST 

100 100 • 100 

90 (/) 

1- 90 90 z 

ILl (/) 80 ::!: 

80 (/) ILl ILl 0 80 ILl > z 1- lr 0 0 

(/) C) ::!: 0 

ILl ILl 70 70 ILl 70 

1- 0 ILl (/) 

>- ILl 3!:: ILl 

0:: (/) 60 0 60 (/) 60 

a.. :::::> ::!: :::::> ::!: 

C) C) ::!: Experimental Groups : C) lL. ~ 50 ex 50 0 1- ~ 50 I (IW) 6--6 (/) (/) (/) 1- >- >- >- n (26. c> z ·--· z 40 z 40 z ILl 40 m<30•c> c--o ILl IL. u (/) 0 IL. 

0:: <{ 0 

ILl I 30 lr 30 z 30 a.. Q. ILl 0 Ill 

~ Stimulus: 3: c ::!: 

0 20 ::::> 20 lr Bilateral Caloric .J z 20 :::::> (/) 0 R30° C; L46°C 

10 10 10 for 20 sec 

0 0 0 PRE POST PRE POST PRE POST 

TRIALS 

FIGURE 1. Mean pre- and post-test b'ilateral caloric scores for slowphase displacement, beat-frequency, and duration 

of response for the experimental groups and for the control groups plotted as percentages of the pre-test. 

8 
EXPERIMENTAL GROUPS 

GROUP I : CAT 154 

PRE ~!I/INIIIIIAM/1NvNJWI/Vv.AJVVW1/IMMAAWf\,A,f\~,v.JW!i,WWMfi1.WJJJftMMN 

1NJV'AAMMMMM.Vv 1AAMM..AMM/tf\JVIM~MMM/WIAA/INIMf'INif.MNAAJIIMN'/Nift/I/IIIA W/'IVIN'I"'A 

POST 

GROUP li: CAT 169 

PRE .~\A l~J~J~~}.~.~/IJ1.A~v;~JfijV)~fJN1}Jv1~fiM~N~fifi.~ANfi~Mfl~!lAftl#~NlW 

~MN~k.ll:1~AAMfi~Nvlfi.~~/if1Nfi.ffiA~VW ~. 1~/VIfNI/IfiNWfiMfiMM~fiN.~ ·~ WNWt#NN.:JV"'!fiWifMj 

POST ·~~W!1Nl.M. VV\/VvA!\JV\/V\f\rvVlf\tJ'.!f'vJ\IV\!VV 

Mf\lwV~;Vtvv\rJ NVVvvwvvvvvv\A 1\Af\/vv'\NV' 30•L 

I SEC 

GROUP m: CAT 172 

PRE~~~~· 

Nw~~· 'lfVVv/vvVVV\N'{~ 

BILATERAL STIMULUS : 30• C to Right Ear and 46° C to 

Left Ear for 20 Sec 

30·L 

I SEC 

FIGURE 2. Pre- and post-test tracings of bilateral caloric nystagmus for cats in the three experimental groups. Vertical bars mark the .termination of the stimulus period. 

9 
CONTROL GROUPS 

CALORIC CONTROL 1 CAT 184 

PRE "--t" \..--\.1\ '\/"-V\/ V\/\.~V\,J \JV\!vvvvV""-" ~. 'V\J\.1\_j \! \!\. .. ' j,...\1-J\1\_ 

A_~ -J~!\M""-.l\Ai'Vvvv-~-~)\.JVV\.1\1\1\1\1\_"j\!\l'.f\~J· 

POST --

~~L 

I SEC 

ROTATION CONTROL: CAT 191 

PRE 

~L I SEC 

COMBINED CONTROL: CAT 208 

PRE ~/\y\/1,_/V~JVt·vv~Vv\/VV 

'\~ -v--------

/\._,. ~~./\./\../\/"'~-v---"\/\./\. /\./-v---\...- 3()-L 

BILATERAL STIMULUS : 30• C to RIQht Ear and 46• C 

to Left Ear for 20 Sec 

I SEC 

FIGuRE 3. Pre- and post-test tracings of bilateral caloric nystagmus for cats in the three control groups. Vertical 

bars mark the termination of the stimulus period. 

10 
UNHABITUATED DIRECTION 

100 100 

~ 100 

~ 

90 

80 

en 

~ 

.... 80 

90 

en 

0 

90 

80 

~ D 

z I&J 2 0 

a: I&J 0 

~ 70 > I&J 070 en 70 

0 2 ~ I&J 

en 60 ~60 en 60 ::» ::» 0 2 I ~~ i50 :! ~ .... ~ en 

en .... ,.. 

,.. ~ 40 z40 z 40 

z 

I&J "' 0 

en "' z Cl 30 030 0 30 X a: ~ ll. 

~ I&J 

20 120 a: 20 1- ...1 ::» 

en en ::» 0 

LLI z 

1- 10 10 10 

UJ 

0: 

Cl. 

LL PRE POST PRE POST PRE POST 

0 

1-

HABITUATED DIRECTION 

z 100 100 

~ 100 LLI 

0 

0: 

UJ 90 90 90 

Cl. en D 

Ci) .... en 

1!: 80 ~ 80 ~ 80 

a: 2 0 

0 (!) I&J I&J 

~10 ~10 en 70 

2 ~ ~ 

~ 60 ~60 • ~ 6o 

2 I&J 2 Experimental Groups 

(!) 0 (!) I (IW) 6 6 :!50 i 50 :!50 D (26•) •--• en (!) en 

,.. :! ,.. m (30•> a a 

z 40 z ~ 40 "'40 I&J z 0 en Stimulus: f30 ~30 z 30 0 Rotation 

~ 20 

a: ~ s•t sec:2 for 12 sec I&J 

CD 20 a: 20 en ::» 2 0 ::» 

z 

10 10 10 

PRE POST PRE POST PRE POST 

TRIALS 

FIGURE 4. Mean pre- and post-test rotation scores for slowphase displacement, beat-frequency, and duration of re- sponse for the experimental groups plotted as percentages of the pre-test. 

11 
UN HABITUATED DIRECTION 

100 (/) 100 100 

1- (/) (/) 

w z 0 

w 90 w 90 tj 90 0::: ~ 

w u ffi > i LIJ 

0 80 0 80 (/) 80 ~ z 

(/) w • (/) 

:::> 70 >- 70 :::> 70 ~ w ~ (!) u (!) 

~ 60 ~ 60 ~ 60 

(/) (!) (/) 

>- ~ >- z 50 (/) 50 z 50 >- LIJ z IJ... 

(/) 0 

<t 40 IJ... 40 z 40 I 0 0 1- a.. 

0::: i= en ;: 30 w 30 <t w 30 g m 0::: 

1- ::!E :::> 

(/) :::> 0 

w 0 z 0 0 

a:: PRE POST PRE POST PRE POST 

Q_ 

LL 

0 

1-

z HABITUATED DIRECTION 

w 

u 100 (/) 100 100 a:: (/) 1-

w z (/) LIJ 

~ 90 0 Q_ w 90 z 90 0::: 

LIJ 0 (!) 

w > u 

80 0 80 m 80 0 ::!E 

(/) w ~ 

:::> 70 >- 70 (/) 70 ~ LIJ :::> • (!) u ::!E 

~ 60 <t 60 ~ 60 Control Groups : 1-

~ (/) • (/) 

.Caloric ._. >- ~50 z >- 50 z 50 Rotation ·-· w >- IJ... 

(/) z 0 Combined o-o 

<t 40 ~ 40 z 40 I 

a.. 0::: 0 Stimulus: 

• ~ 30 ~ 30 ti 30 Rotation 

::!E 0::: 5•1sec2 for 12 sec ....I ::::> (/) ::::> 0 0 z 0 0 

PRE POST PRE POST PRE POST 

TRIALS 

FIGURE 5. Mean pre- and post-test rotation scores for slowphase displacement, beat-frequency, and duration of re- sponse for the control groups plotted as percentages of the pre"test. 

12 
100 100 

(I) 

90 ... 90 - z U) LIJ LIJ 2' LIJ 

a:: 80 LIJ 80 

C) > •, 0 LIJ 

0 2 ' 70 • 70 ' .... \ ---... ---- ' 

\ ' LIJ ,, (I) ~ 

:J 60 \ LIJ 60 2 \ 

C) \ 0 

~ ~0 

\~ :i ~0 

(I) 

~ ~ z 40 ... ~ U) 40 ~ LIJ ..... z (I) 

C( 30 30 &&. X 0 ~ 0.. 

(/) 31: 20 a:: 20 Caloric Control Group 0 w ...J LIJ 

~ (I) m 

10 2 10 Post Rotations ::::» 

z 

w 0 0 0::: Pre Post I 2 5 4 !5 Pre PMt I 2 5 4 !5 

a.. '--Additional----' '--Additional----' 

LL 

0 

~ 100 \ , 100 \ z \ U) 

w \ .... 0 - 90 \ z 90 

(I) • LIJ 

0::: LIJ \ 2 • 

LIJ \ LIJ \ w a:: 80 \ ~ 80 \ 

a.. C) \ \ LIJ \ 2 \ 0 70 70 - \ LIJ \ 

\ 

U) •, ~ • ::::» 60 \ LIJ 60 \ 

2 \ 0 . \ 

C) \ 

U) 

(I) 

LIJ 

z 

~ 

~ 

40 

!50 • \ 

\ 

i 

U) 

C) 

~ 

z 

~ 40 

!50 

~ C[ 30 &&. 50 

X 0 

0.. 

31: 20 e-e Habituated Direction a:: 20 Rotation Control Group 0 l&J 

...J CD 

U) 

10 •--• Unhabituated Direction 2 10 Post Calories :J 

z 

0 0 

Pre Post I 2 5 4 Pre Post I 2 3 4 

'-Addltlonai......J L-Addltlonai......J 

TRIALS 

FIGURE 6, Mean slowphase displacement and beat-frequency scores for the additional post-tests .plotted as percentages 

of the pre-test. The upper figures illustrate values for post-rotations, and the lower figures for post-calories. 

13 
WEEK RETENTION 

100 • • 100 

\ (/) ' \ t90 \ z 90 \ .... 1&.1 (/) \ 

1&.1 \ ~ \ 

1&.1 80 \ 1&.1 80 \ 

a: \ > • 0 \ (!) 

~ \ 1&.1 ~ 0 -70 \ 70 \ 

- \ 1&.1 \ .--"'- \ (/) >- '.----· \ 1&.1 :::> 60 60 -·\ \ 2 -- 0 (!) 

4 :i 50 t- 50 .......... (!) (/) 

>- • ~ z 40 (/) 40 

>-

1&.1 z • (/) 30 30 4 ~ t- X 

C/) Q. • 31: 20 a: 20 

w 0 1&.1 

t- ..J ID (/) 2 Average for 8 Cats 10 10 :::> 

w 

z 

a:: 0 0 

Q. Pre Alit 2 3 4 2 3 4 Pre Post 2 3 4 2 3 4 

Rclw Rwlc Rclw Rwlc 

IJ.. 

0 MONTH RETENTION 

t- 100 • 100 • • \ z (/) 

t- \ w .... 90 z 90 \ 0 (/) 1&.1 

a:: 1&.1 • 2 \ 

1&.1 80 ' 1&.1 80 w a: \ \ > 

Q. (!) 0 • \ 1&.1 • \ 2 \ 0 70 \ \ 70 \ - \ 1&.1 \ 

(I) \ >- •, 

;::) 60 "' 60 \ 'e... 2 \ .... ! • \ ~ 

50 \ \ 2 50 \ z 

~ .......... 

' ~ 40 (/) 40 

\ >-

1&.1 ... z 

(I) 30 .\ 4 L&.. 30 • 

% 0 

Q. 

31: 20 a: 20 

g 1&.1 

ID Average for 7 Cats (/) 10 ~ 

;::) 

z 

0 0 

Pre Post 2 3 4 2 3 4 Pre Post 2 3 4 2 3 4 

Rclw Rwlc Rclw Rwlc 

TRIALS 

FIGURE 7. Mean slowphase displacement and beat-frequency scores at one week and at one month following the 

habituation series plotted as percentages of the pre-test. 

14