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differences between the HFS and LFS Ss for
both the PR task (p<.001) and the PT task
(p<.01) respectively, with HFS Ss exhibiting
relatively greater performance impairment. Sig-
nificant HR differences were also found between
the HFS and LFS groups. Table 2 shows that
HFS Ss assigned the PR task have significantly
higher HR’s relative to LFS Ss (p<.01) and
HES Ss assigned the PT task show similar dif-
ferences in comparison to LFS Ss (p<.001).

Taste 1. Comparison of Mean Performance Change
from Training to Testing Phase of High and Low Fear
of Shock Subjects.

Chi

ase | eroup] BRE | vastance| + |p
HFS 0.57 2.05,

Pursuit Rotor 4.52 | .001
LFS 3.60* 2.48
HFS 0.70° 2.03

Press Test 3.73 | .OL
LFS 3.54? 3.94

1. Mean Time on Target (secs.).
2. Mean Correct Responses.

‘Taste 2. Comparison of Mean Heart Rate Change from
Training to Testing Phase of High and Low Fear of
Shock Subjects.

Mean Heart
ate Change
‘Task Group (bpm) Variance} ¢ | p
HFS 25.2 192.10
Pursuit Rotor 3.27 |.01
LFS 69 130.84
HFS 26.0 26,22
Press Test 4.22*) 001
LFS 4.0 245.55,

*Computations based on two sample t-test where variances
are considered unequal (Walker and Lev 1953, pp. 157-158).

IV. Discussion.

The results suggest that an attitude question-
naire may be used effectively to elicit differences
between Ss toward a possibly threatening object
or situation, and that the subsequent behavioral
manifestations of these expressed evaluations may
be reliably reflected in terms of both performance
and heart rate response patterns. The data thus
confirm the previous findings of Thackray and
Pearson’ and suggest further that an individ-
ual’s cognitive appraisal (expressed attitude) of a
threatening object or situation may be subse-
quently manifested in a consistent manner ir-

respective of the task employed. This latter
condition, however, may apply only within cer-
tain limits insofar as consistency across tasks is
concerned. For example, Murphy’ has shown
that the introduction of some types of tasks may
confound results due to the fact that the task
itself may be stress inducing. This could have
the effect of masking differences between groups
exposed to a specific stressor despite prior classi-
fication of Ss on the basis of their expressed at-
titude toward the externally imposed stress situa-
tion. Thus, it is necessary to determine the ex-
tent to which a task may differentially affect the
performance and/or physiological reactivity of
groups which have been classified a priori as dif-
ferent before the introduction of the stressor
under investigation.

The results of this study, taken together with
those of Hodges and Spielberger® and Thackray
and Pearson” suggest that the direct, objective
assessment of attitudes toward specific stress
situations may have greater heuristic value in
stress research than approaches which rely upon
self-descriptive inventories of general anxiety.TM
To the extent that different degrees of threat may
be elicited by different stressors, the assumption
that “high anxious” individuals are also high
in stress. susceptibility, regardless of the nature
of the stressor, may be one of the principle rea-
sons for the lack of success of most self-descrip-
tive anxiety inventories.* It should be noted that
in neither the previous study by Hodges and
Spielberger® nor the later study by Thackray and
PearsonTM® was a relationship obtained between the
TMAS and the “fear of shock” classification, al-
though the “fear of shock” classification was
highly predictive of behavioral response to the
induced stressor of threat of shock. Thus, the
use of general or nonspecific items, such as “more
fearful than my friends,” (a typical statement
found in the TMAS) may connote fears of quite
different stress situations to different individuals,
all of whom may be classified as “anxious.” If
this is the case, it would seem more appropriate
or advisable in stress research for an Z to in-
troduce stressors that are consistent with a S’s
cognitive appraisal of the specific stressor, i.e.,
if a subject indicates fear toward a threat of
shock situation it would be expected that sig-
nificant performance or physiological changes
would occur whenever shock or the threat of
shock is introduced.


titude toward the specific stressors is a separate
issue which will not be treated here. The present
study was designed, using a between-groups ap-
proach, to examine only the related question of
whether or not relative performance change and
physiological reactivity of Ss classified according
to their attitude toward a specific stressor are in-
dependent of the type of task when the stressor
remains constant. It was predicted that (a) Ss
expressing a HFS would perform significantly
below the level of Ss expressing a LFS under a
threat of shock condition, (b) that HFS Ss
would exhibit greater increases in heart rate than
LFS Ss under a threat of shock condition, and
(c) that performance and heart rate changes for
the HFS and LFS Ss would exhibit consistent
differences in the direction predicted in (a) and
(b), above, for both a perceptual-motor and cog-
nitive-interference type task.

Il. Method.

Subjects. Ss were male undergraduates from
the University of Oklahoma, ranging in age from
18 to 25 years. Selection of Ss was based upon
scores obtained from an attitude questionnaire
containing items relating to a number of poten-
tially stressful situations. The questionnaire was
administered by an associate 1 month prior to the
experiment. Each item was rated on a seven-
point (equi-distance) scale ranging from “slightly
concerned” to “strongly concerned.” Ss respond-
ing to the first two or last two equi-distance
spaces of the “fear of shock” item under study
were classified as HFS or as LFS types. From
a larger group thus classified as HFS or LFS
types, an associate randomly selected 20 Ss from
each classification as participants in the experi-
ment. All Ss were informed only that they had
been randomly selected to participate in a motor-
learning experiment.

Apparatus. Performance tasks consisted of a
modified, commercial version of the Stroop
Test, called the Press Test (PT),? and a pursuit
rotor (PR) (LaFayette Instrument Co., Model
2203A. with hinged stylus) attached to a Hunter
Model 120 A Klockounter (Series D). The PT
task contained three separate parts. Part I re-
quired the S to write down the first letter of a
series of color names printed in black ink; Part
II required the S to write down the first letter
of the color of a series of different colored circles.
Part III consisted of color words printed in in-

congruent ink colors; the S’s task was to write
down the first letter of the ink color and to ig-
nore the name of the color. The PR was main-
tained at a speed of 60 r.p.m. throughout the ex-
periment. Beckman biopotential electrodes at-
tached to the lateral walls of the $’s lower rib
cage were used to obtain heart rate (HR), which
was recorded on a Beckman Type R Dynograph.
Eye blinks, obtained from Beckman miniature
biopotential electrodes attached immediately
above and below the left eye, were recorded for a
separate purpose and will not be reported here.
An electrocardiogram (EKG) plate electrode was
attached to the wrist of the S’s nonpreferred
hand (the hand not normally used in writing)
which served as a ground. The “dummy” threat
of shock apparatus was an Applegate Model 230
stimulator. All Ss performed while seated in a
wooden cubicle containing the PR or the PT task.
A one-way vision glass inserted in the front of
the cubicle provided the experimenter (Z) with
an unobstructed view of the S. Two tape re-
corders were used for presenting all instructions.

Procedure. Half of the 20 HFS Ss were as-
signed to the PT task and the other half to the
PR task by means of a rotational schedule. The
same procedure was followed for the LFS Ss. If
the first S was given the PR task, then the second
iS was given the PT task, etc. The Z' was given
no knowledge by an associate as to any S’s HFS
or LFS classification. 2 escorted each S to the
experimental room and instructed him to be
seated inside the cubicle. All further instruc-
tions were on tape recordings. Following an
initial greeting, an explanation of the purpose of
the experiment was given. The purpose was
disguised to the extent that Ss were not told any-
thing about the experiment beyond the fact that
they were being tested with respect to studying
the effects of generalized muscle tension on learn-
ing, and that this was the reason for using elec-
trodes. Ss were also told that the purpose of
the one-way mirror provided the # with the op-
portunity to know when to assist them in the
event that the performance instructions were not
entirely clear. Electrode attachments were then
made and the Dynograph adjusted. (See
Figure 1).

Ss assigned the PT were given all three parts
during the training phase, with each part con-
sisting of five 20-second trials, with 20-second
rest periods between each trial. Separation of


trials was accomplished by having the S draw a
line under the last response of each trial. The
score consisted of the total correct responses
minus errors. Ss assigned the PR task were also
given 15 trials with 20-second rest periods be-
tween each trial. The score of each trial con-
sisted of the total time that the 8 kept the stylus
in contact with the metal target disk of the PR.
The total time of each trial was recorded by the
E,. HR was recorded continuously throughout
the experiment.

Following completion of the training phase, Ss
were given a 3—minute rest period after which
identical test-phase instructions were played for
Ss assigned either the PT or PR task. All Ss
were informed that the next phase of the experi-
ment would be essentially the same, except that
now they would have to perform under threat
of shock if they failed to maintain the average
performance level established during the training
phase; ie., if their performance dropped below
the previously obtained average score, they would
receive an electrical shock. They were further
told that the shock, should they receive it, would
not be harmful but would be uncomfortable and
that the # had no control over the possible re-
ceipt of shock since the shock apparatus would be
adjusted to automatically deliver electrical cur-
rent should performance drop. The £ then
turned off the recorder and placed the “dummy”
shock apparatus in a position clearly visible to
the S. A white cloth, which prevented the S
from seeing it prior to this time, covered the ap-
paratus. Two EKG plate electrodes were then
fastened to the S’s leg. The apparatus was
plugged into a wall outlet which, in turn, il-
luminated a green “power-on” light. Two face
dials were manipulated while the S watched in
order to enhance his belief that the apparatus was
capable of delivering the promised electrical cur-
rent. (See Figure 2). All Ss were then given
an additional five trials. Only Part III of the
PT task, requiring. complex discrimination judg-
ments, was used for the testing phase since it was
felt. that the lack of task complexity of Parts I
and II would result in too low a task demand
with resultant loss of measurable response dif-
ferences between the training and testing phase.

At the completion of the experiment all Ss
were requested to complete a post-experiment
form containing an item designed to tap their
feelings about the possibility of receiving shock.

They were then congratulated for maintaining
their performance average and thus avoiding
shock, This was done to reduce § rumor that
no shocks were actually being used in the experi-
ment.

Ill. Results.

Prior to the introduction of the experimental
condition, ¢ tests of mean differences between the
HFS and LFS groups conducted on HR and on
the PR and PT performance measures during
training revealed no significant differences at the
.05 level. Additionally, tests for homogeneity of
variance between HFS and LFS groups on HR
and performance measures indicated no signif-
icant differences. Training data selected for anal-
ysis consisted of the mean score and mean HR
of the last five trials for both the PR and PT
tasks.

Test phase performance measures for the PT
consisted of the algebraic difference between each.
8’s mean score on the last five 20-second training
trials (Part III), and his score on the first 20-
second test trial (Part III). Although five test
trials were given to each S, only the first trial
was used in data analysis. This was deemed ap-
propriate due to the fact that maximal effects of
a threat of shock situation are generally obtained
during the first trial, with progresssively less ef-
fect being present thereafter if the threat of
shock is not reinforced. Further, it was felt that
the most appropriate measure of the training
phase should be the mean of the last five trials
rather than the last trial itself in order to re-
duce error variance as much as possible. PR per-
formance measures used in data analysis were
obtained by the same method described above for
the PT task. Likewise, HR measures consisted.
of the algebraic difference between the mean
number of beats during the last five 20-second
training trials and the number of beats during
the first 20-second test trial. AJ] HR scores were
multiplied by three to convert them to a rate-
per-minute base. The periods scored for HR
were the same as those employed for performance
analysis in order to:make the data as comparable
as possible.

In analyzing the test phase data, ¢ tests of the
difference scores between training and testing for
HFS and LFS Ss performing the PT or PR task
and HR were made. The summary analysis pre-
sented in Table 1 reveals significant performance


a

2

a

. DEEsE, J.

. HorvatH,

REFERENCES

|. Ax, A. F.: Goals and methods of psychophysiology.

Psychophysiology, 1:8-25, 1964.

. Barr, M. E., Corsrni, R. J., and RencK, R.: The

press test. Education-Industry Service,

1961.

Chicago,

Skilled performance and conditions of
stress, In R. Graser (Hd.), Training research and
education. Pittsburg, University of Pittsburgh
Press, pp. 199-222, 1962.

Grice, G. R.:
the source of experimental variation.
Bulletin, 66 :488-498, 1966.

Dependence of empirical Jaws upon
Psychological

. Harris, W., Mack, R. R., and Wison, C. L.:

Performance under stress: a review and critique
of recent studies. Human Factors Research, Inc.,
‘Technical Report VI, Los Angeles, California, 1956.

. Hopes, W. F., and Spreveercer, ©. D.: The effects

of threat of shock on heart rate for subjects who
differ in manifest anxiety and fear of shock. Psy-
chophysiology, 2:287-294, 1966.

F. E.: Psychological stress:
of definitions and experimental research.
Systems Yearbook, 4 :203-231, 1959.

a review
General

. Jounson, L. C., and Lusrn, A.: On planning psy-

chophysiological eaperiments: design, measurement
and analysis. Navy Medical Neuropsychiatric Re-

10.

i

12,

13,

14.

15.

16.

search Unit, Report No. 67-19, San Diego, Califor-
nia, 1967.

. Lazarus, R. S., Derse, J., and Oster, S. F.: The

effects of psychological stress upon performance.
Psychological Bulletin, 49 :2938-317, 1952.

Moreny, R. E.: Effects of threat of shock, distrac-
tion, and task design on performance, Journal of
Experimental Psychology, 58:134-141, 1959.
Nunnatty, J.: Tests and measurements. New York,
McGraw. Hill, 1959. -

Opron, E. M., and Lazarus, R. S.: Personality de-
terminants of psychophysiological response to stress:
a theoretical analysis and an experiment. Journal
of Personality and Social Psychology, 6 :291-808, 1967.
Poutron, E. ©., and Freeman, P. R.: Unwanted
asymmetrical transfer effects with balanced experi-
mental designs. Psychological Bulletin, 66 :1-8, 1966.
Srroop, R. J.: Studies of interference in serial
verbal reactions. Journal of Eaperimental Psy-
chology, 18 :643-€662, 1935.

‘Taytor, J. A.: A personality scale of manifest anx-
iety. Journal of Abnormal and Social Psychology,
48: 285-290, 1953.

Trackray, R. I., and Pearson, D, W.: Effects of
cognitive appraisal of stress on heart rate and task
performance. Perceptual and Motor Skills, 27:651-
658, 1968.



AM 69-7

CONSISTENCY OF PERFORMANCE CHANGE AND
AUTONOMIC RESPONSE AS A FUNCTION OF EXPRESSED
ATTITUDE TOWARD A SPECIFIC STRESS SITUATION

David W. Pearson, Ph.D.
Richard I. Thackray, Ph.D.

Approved by Released by
J. Rozerr Diiiz, M.D. P. V. Smert, M.D.
Cuter, Crvi, ArroMEDICAL Fepera Am Surcron
Instrrure
April 1969

Department of Transportation

FEDERAL AVIATION ADMINISTRATION
Office of Aviation Medicine



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Qualified requesters 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.


CONSISTENCY OF PERFORMANCE CHANGE AND
AUTONOMIC RESPONSE AS A FUNCTION OF EXPRESSED
ATTITUDE TOWARD A SPECIFIC STRESS SITUATION

I. Introduction.

Aviation occupations often require the per-
formance of tasks under stressful conditions
which may impair performance. Although a
great deal of research on the effects of stress on
performance has been reported, many problems
still remain unanswered,’ the foremost of which
is the problem of individual differences in stress
susceptibility.’ It is well known that some in-
dividuals show performance impairment under
certain stress conditions, some improve in per-
formance, and others show no change? Iden-
tification of the personality variables responsible
for the differences in the behavioral and/or
physiological response of individuals under stress,
however, has generally not been too successful.
This has been particularly true whenever general
anxiety measures, such as Taylor’s Manifest
Anxiety Scale (TMAS),* have been used.*7 Re-
cently, emphasis has been placed upon the in-
dividual’s cognitive appraisal of a stress situation
as a determining factor which may affect per-
formance, i.e., an individual’s attitude toward the
object of stress may determine, to a considerable
degree, his response to stress.

The hypothesis that a subject’s (Ss) attitude
toward an object he considers threatening may
account for much of the variance in stress sus-
ceptibility has received support from several re-
cent studies. Hodges and Spielberger® reported
significant heart rate differences between individ-
uals classified as low fear of shock (LFS) types
and those classified as high fear of shock (HFS)
types on the basis of the individuals’ prior ex-
pression of fear toward a threat of shock item
embedded in a multi-item attitude questionnaire.
More recently, Thackray and Pearson’® found
essentially the same heart rate relationships be-
tween HFS Ss and LFS Ss as were reported by
Hodges and Spielberger. Both studies found
that HFS Ss exhibited greater increases in heart

rate under a threat of shock condition relative
to LFS Ss. Additionally, Thackray and Pear-
son" reported significant performance differences
between the HFS and LFS groups. It was
found that HFS Ss demonstrated significantly
greater performance impairment on a perceptual-
motor task (pursuit rotor (PR)) relative to the
performance levels of the LFS Ss. No 8 in this
latter study was aware that threat of shock would
be used as the stressor prior to the test phase of
the experiment. Shock was not actually admin-
istered to any S. In addition, both studies
showed no relationship between S’s expressed at-
titude toward fear of shock and scores obtained
on the TMAS.

To the extent that an individual’s perception
of threat is specific to a given stressor, it could
be predicted that any performance impairment
occurring under that stressor would not occur
under a different stressor which was not per-
ceived as threatening. It could also be predicted
that if a given stressor is perceived as threaten-
ing, any change in performance should not be
specific to the particular task employed. How-
ever, rather than expose the same individual to
a variety of stressors or a variety of tasks within
a common stressor and then attempt to determine
whether differences in perceived threat are re-
lated to performance differences as suggested by
Opton and Lazarus, an alternative would be
to separate individuals in advance on the basis
of differing attitudes toward specific situations.
Thus, between-groups comparison of Ss separated
on the basis of a variable, such as an expressed
attitude common to each group toward a specific
stressor, with each group exposed to this single
stressor, would eliminate some of the problems
of a repeated measures design.5)*

The question of whether response consistency
or lack thereof across stressors can be predicted
from a knowledge of an individual’s prior at-