ferent in the cold and during the morning ex-
posure, but that T, did not vary through time.
RR was lower in the morning than in the after-
noon, but was not influenced by differences in
chamber temperature or through time. Com-
parisons between the neutral and hot environment:
indicated significant increases in all the param-
eters due to chamber temperatures. T, showed
no direct effects from morning to afternoon, or
through time, and, as in the cold, there was no
change in RR through time. Changes in Ty
through time in the cold were largely due to the
significant decrease in T,, as T, did not change
with time, whereas those in the heat were in-
fluenced more by the increasing T,, as T, did not
change significantly through time. The inter-
action between chamber temperature and time
also supports this result.

22580. 08,
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the skin by convection for subsequent dissipation
by evaporation of sweat at the surface.

Mean heat debts calculated for morning and
afternoon exposures, were 102 and 181 kcal in
the cold; and 23 and 13 kcal at the neutral con-
ditions respectively, whereas, subjects exposed to
heat showed mean heat gains of 26 and 48 kcal
in the morning and afternoon respectively.

The curves in Figure 4 show changes in tem-
perature of the palm of the hand for the three
environments. Mean hand temperature in the
heat rose 1.6°C in the morning and 2.6°C in the
afternoon, whereas those in the cold fell 7.9°C
in the morning and 10°C in the afternoon. Tem-
peratures at neutral conditions remained fairly
stable. Tests for significant differences between
means of paired data**, showed that the afternoon

Cc

Frcure 2. (A) Board with rivets and washers for finger dexterity tests. Rod containing
washers is attached to the right side of the board for left-handed test subjects.
(B) Correct method of assembling a rivet and washer for a right-handed subject.
(C)Three-line configuration for motor coordination test.

Further interactions of chamber temperature
with exposure time and with time of day (AM-
PM) showed that the apparent increase in heart
rate at 10°C was probably due to the low morning
rates observed at 267°C, whereas increases at
46°C were caused more by the higher chamber
temperature rather than time of day. Heart
rate also increased with exposure time in the
heat, promoting transfer of deep body heat to

values in the cold were significantly lower than
morning values from 80 minutes through 60
minutes. Reasons for this temperature inversion
are not clear. Temperatures at 75 and 90 min-
utes were not significantly different probably
because of the large variability caused by ex-
cessive movement during the dexterity tests.
Results of CIVD (Figure 5) were analyzed
for six combinations of rectal temperature and



both speed and accuracy in arithmetic problems
deteriorated, but that vigilance was improved.
Wing”, using effective temperature (ET) to de-
fine upper thermal tolerance limits of mental
performance for a variety of tasks, showed that
the physiological limits were always higher than
those for mental performance, and that impair-
ment occurred at an ET of 31.7°C for a 2-hour
exposure, a value somewhat lower than the ET
of 35°C, calculated for the hot condition of this
study. Impairment here may be due to the na-
ture of the test, which measures the ability to
coordinate eyes and hands or fingers rapidly and
accurately, rather than the degree of cortical
activity. Gaydos"t exposed men to 7.2°C but
found no impairment of tying knots or stringing
blocks as long as hand skin temperature was
maintained at 27°C, while Clark and Cohen’
thought that decrements in performance accom-
panying cold exposure increased as the rate of
hand cooling decreased. The consistently poor
showing of finger dexterity in the men exposed
to 10°C was probably not caused by any loss of
tactile discrimination of the fingers, as Morton
and Provins*** exposed the index finger to cold
air or to cold water, and found no deterioration
above finger temperatures of 8°C, or about 7 to
10 degrees below the mean initial finger tem-
peratures measured here (Figure 5A). LeBlanc”
and Hunter* independently reported impairment
of finger dexterity in the cold, and thought it
to be due to increased viscosity in the synovial
fluid of the joints of the fingers and hand. There
may have been some stiffening of the joints of
the fingers of subjects at 10°C, but comparisons
were difficult because the methods of cooling
differed from those in the literature.

The lack of CIVD response in all subjects
exposed to 10°C: and in the four exposed to the
higher ambient conditions may have different
causes, Blaisdell studied men for several hours
and found induced vasodilatation to occur, even
when the body was chilled at ambient tempera-
tures down to 12°C, although cycling time in-
creased at the lower temperatures, and KeatingeTM®

found that finger vasodilatation in chilled men
may be delayed as long as an hour and a half.
Thus, the subjects here might have vasodilated
if exposure time had been extended beyond 20
minutes. Absence or impairment of the CIVD
response in subjects in a comfortable or warm
thermal state may be attributed to effects other
than temperature or individual variability.
Bader and Mead? showed that with subjects ade-
quately warm, both hand and finger cooling pro-
duced no changes in blood flow in the cooled
finger as compared to a control finger except
when the subjects were startled by a loud noise
or took a deep breath. Then vasoconstriction,
accompanied by reduced blood flow and finger
cooling occurred in both the cooled and controlled
digits. Adams and Smith, Meehan”, and Teich-
ner** found that an emotional disturbance such
as anxiety elicited vasoconstriction in the finger,
resulting in delayed cycling time or absence of
induced vasodilatation. Possibly apprehension
of the unusual test situation was a contributing
factor here, but as none of the subjects were
evaluated psychologically, speculation only can
be made on this point.

The higher hand and finger temperatures of
subjects at 10°C (Figure 4) which occurred at
the lower T,, may have been induced by excessive
shivering. Carlson* found that the adequate
stimulus for shivering depended in part on the
central thermal state, and that lowered internal
body temperature encouraged the tendency to
shiver. Morning T, rose 0:5°C during the initial
45 minutes in the resting men, indicating either
a higher degree of shivering or more efficient
heat conservation over that of the afternoon ex-
posure (Figure 3C). Possibly both muscle and
cutaneous blood flow were increased enough to
raise the hand temperature.

The physiological and manual performance
data suggest that decrements in dexterity, par-
ticularly those involving kinesthetic sensitivity,
depend largely on maintaining the integrity of
the shell temperature, with the core temperature
in a secondary role.


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21F © 26.7°C —---- P.M
A 46.0°C
1 it 1 1 it L iN J
0 15 30. 45 60 75 90 105 120
TIME (min)

Figure 4. Hand temperatures (palm) at ambient temperatures of 10°C, 26.7°C, and 46°C.

average skin temperature, by comparing the
means in a paired “t” test”®.

The most striking feature of subjects in the
cold was the absence of spontaneous vasodilata-

_ tion. Initial finger temperatures (temperatures

in air prior to immersion, Figure 5A) and cool-
ing rates (rate of cooling for the first 3 minutes
of immersion, Figure 5B) were significantly

n=6.

higher at the low rectal temperatures. Initial
finger temperatures in the heat were higher than
those at the neutral conditions, which in turn
were higher than those in the cold. Cooling
rates at the neutral conditions were also higher
than those in the cold, but rates in the heat were
higher than at neutral only for the low rectal
temperatures. Rewarming rates (Figure 5D)



RR (breaths/min)

HR (beats/min)

Tr (°C)

DEGREES CENTIGRADE

n

©

N

a

130

110

90

70

40

38

36

40

38

36

34

32

30

28

26

267°C

KL
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a — AM.
b a ---- PM.
L Nan & ats
L Brag ° Ty
be ee
{e) 30 60 90 120 oO 30 60 90 120 {e) 30 60 90 120
TIME (min)
Ficure 8. Physiological responses to ambient temperatures of 10°C, 26.7°C, and 46°C, n=6.

4


°c

— N=6 nee
407 A yee NES
39.7
Ne6 33.8 39.1
207 N=6 373 £120 £1.18 £075
19.0 159
£0.36 +077
0
INITIAL TEMPERATURE
°C /min.
20r B
lo [ Nee N=6 Neé Ne6
N=6 2 .! 10.6 1.8 10.9
r 5.6 ws +058 £0.33 £0.43 £0.43)
° £0.22 £0.18
COOLING RATE
min
20° Cc
lr Nes
L NSS
10 11.84 Nea
E *x * £0.44 5 55, Nea
° . £1.39
CYCLING TIME
°C/min
4.07 H
3.0F Nea
2.0F Nes 28 N=4
0.5 N=S £0.38 7
lok * * 235, Nes wits
20.18
°
REWARMING RATE
°c
MOTE wea NSS
ak
an t 8.7
ar Nes NeS thos £0.33
* * 1054 37
er £1.26
°

REWARMING TEMPERATURE
Low Tg High Te Low TR High TR: | Low TR High Tr
Low Tg Low Tg Neutral Tg Neutral Ts High Ts High Ts

2% NO RESPONSE

Ficure 5. Thermal responses of the right index finger immersed in stirred ice water for 20 min. for six body
thermal states.

7



AM 68-13

THE EFFECTS OF BODY THERMAL STATE
ON MANUAL PERFORMANCE

J. A. Vaughan, B.S.
E. A. Higgins, Ph.D.
G. E. Funkhouser, B.S.
Elinore M. Galerston, B.S.

Approved by Released by
J. Rosert Duis, M.D. P. V. Smcrr, M.D.
Cuter, Civin AEROMEDICAL Feprrat Arr SurcEon
InstiTUTe

May 1968

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION
Office of Aviation Medicine



APPENDIX A

Occupational Aptitude Pattern Scores of Experienced
Workers For Ten Aviation-Related Occupations*

Occupational Aptitude Pattern Cutting Scores Occupational Aptitude Pattern Cutting Scores
OAP No. Description Manual Finger OAP No. Description Manual Finger
Desterity Dexterity Desterity Decterity
24 Aireraft and Engine Mechanie 80 22 Assembler, Aireraft Structures
20 Alreratt Mechanic, Armament 85 - Blectriclan Aeplane 2 %
22 Aireraft Mechanic, Heat and 22 “Instrument Panel Assembler —_0 ®
Vent 80 cc) 32 Parachute Maker (Eight
22 —_Alreraft Mechanic, Plumbing categories) 80 80
and Hydranties % * “Extracted from : General Aptitude Test B: B-1002,
. xtracted from : Generul Aptitude Test Battery, B-1002,
22 Alreraft Mechanie, Rigging Section II: Norms—Occupational Aptitude ’ Pattern
and Controls 80 % Structure, Bureau of Employment Security, U.S. Dept.
22 Assembler, Aircraft Power Plant 80 5 of Labor, Washington, D.C, 1966.

10


REFERENCES

1. Avams, T., and Smirn, R. E.: Effect of Chronic
Local Cold Exposure on Finger Temperature Re-
sponses, J. Appl. Physiol., 17: 817-822, 1962.
Baper, M. E., and Meap, J.: Effect of Local. Cooling
on Finger Blood Flow in Individuals Exposed to
Warm Ambient Temperature. J. Appl. Physiol.,
3: 508-512, 1951.

3. Bartirr, D. J., and Gronow, D. G. C.: Manual
Dexterity and Tactile Sensitivity in the Cold. Fly-
ing Personnel Research Committee Report 806, RAF
Institute of Aviation Med., 1952.

4, BrarspELL, R.: Effect of Body Thermal State on
Cold-Induced Cyclic Vasodilatation in the Finger.
Environmental Protection Section Report No. 177,
Quartermaster Climatic Research Lab., Lawrence,
Mass., 1951.

5. Burton, A. C.: Human Calorimetry, II The Average
Temperature of the Tissues of the Body. J. Nutri-
tion, 9: 261-280, 1935.

6. Cartson, L. D,: The Adequate Stimulus for Shiver-
ing. Proc. Soc. Exp. Biol. and Med., 85: 308-805,
1954,

7. Crark, R. BE. and Conen, A.: Manual Performance
as a Function of Rate of Change in Hand Skin
Temperature. J. Appl. Physiol, 15: 496-498, 1960.

8. Cooper, K, B., Jounson, R. H., and Spapine, J. M.
K.: The Effects of Central Body and Trunk Skin
"Temperatures on Reflex Vasodilatation in the Hand.
J. Physiol., 174: 46-54, 1964,

9. Fox, R. H., Gorpsmrrs, R., Hampton, I. F. G., and
‘Wixinson, R. T.: The Effects of a Raised Body
Temperature on the Performance of Mental Tasks.
J. Physiol., 167: 22-23P, 1963.

10. Gayvos, H. F., and Dusex, E. R.: Bffects of Local-
ized Hand Cooling Versus Total Body Cooling on
Manual Performance. J. Appl. Physiol., 12: 877-380,
1958.

11. Gaypos, H. F.: Effect on Complex Manual Perform-
ancé of Cooling the Body While Maintaining the
Hands at Normal Temperatures. J. Appl. Physiol.,
873-376, 1958.

42. General Aptitude Test Battery, B-1002, Section 1:
Administration and Scoring. Bureau of Employment
Security, U.S. Dept. of Labor, Washington, D.C.,
1965.

13. Grayson, J.: Reactions of the Peripheral Circulation
to External Heat. J. Physiol., 109: 53-63, 1949.

14, Haxpy, J. D., and DuBors, E. E.: The Technie of
Measuring Radiation and Convection. J. Nutrition,
15: 461-475, 1988.

15. Horvats, S. M, and Freepman, A.: The Influence
of Cold Upon the Efficiency of Man. J. Aviation
Med., 18: 158-164, 1947.

Nv

16, Hunrer, J., Kerr, E. H., and Waitans, M. G.:
‘The Relation Between Joint Stiffness Upon Expo-
sure to Cold and the Characteristics of Synovial
Fluid. Canadian J. Med. Sci., 30: 867-877, 1952.

17. Iamprerro, P, F., Bass, D, E., and BuskrRK, E.R.
Diurnal Oxygen Consumption and Rectal Tempera-
ture of Man During Continuous Cold Exposure.
J. Appl. Physiol., 10: 398-400, 1957.

18, Kearinas, W. R.: The Effect of General Chilling on
the Vasodilator Response to Cold. J. Physiol., 189:
497-507, 1957.

19. LeBianc, J. S.: Impairment of Manual Dexterity
in the Cold. J. Appl. Physiol., 9: 62-64, 1956.

20. Lewis, T.: Observations Upon the Reactions of the
Vessels of the Human Skin to Cold. Heart, 15:
177-208, 1930.

21, Meznan, J. P.: General Body Cooling and Hand
Cooling. In Fisher, F, R. (B4.) Protection and
Functioning of the Hands in Cold Climates, pp. 45-57.
National Academy of Sciences—National Research
Council, Washington, D.C., 1957.

22, Morton, R., and Provins, K, A.: Finger Numbness
after Acute Local Exposure to Cold. J. Appl.
Physiol., 15: 149-154, 1960.

23, Provins, K. A., and Mosron, R,: Tactile Discrimi-
nation and Skin Temperature. J. Appl. Physiol.,
15: 155-160, 1960.

24. Russert, R. W.: Effects of Variations in Ambient
Temperature on Certain Measures of Tracking Skill
and Sensory Sensitivity. Report No. 300, U.S. Army
Medical Research Laboratory, Fort Knox, Kentucky,
1959.

25, Stony, A. M.: A Wide-Range Thermistor Radiometer
for the Measurement of Skin Temperature and
Environmental Radiant Temperature. The Review
of Scientific Instruments, 25: 184-187, 1954.

26. Tercner, W. H.: Delayed Cold-Induced Vasodila-
tation and Behavior. J. Bap. Psych., 69: 426-432,
1965.

27. Vavenan, J. A., and Apams, T.: Human Diurnal
Rectal Temperatures in a Thermally Neutral En-
vironment. (Unpublished Manuscript).

28, Winer, B. J.: Statistical Principles in Experimental
Design, New York: McGraw-Hill, 1962,

29, Wine, J. F.: Upper Thermal Tolerance Limits for
Unimpaired Mental Performance. Aerospace Med.,
86; 960-964, 1965.

30. WynpHAM, C. H., and Witson-Dickson, W. G:
Physiological Responses of Hands and Feet to Cold
in Relation to Body Temperature. J. Appl. Physiol.,
4; 199-207, 1951.



and rewarming temperatures (Figure 5E) were
not different at any given level of thermal state,
but those in the heat were significantly higher
than those at the neutral conditions.

At neutral skin temperatures, cycling times
(Figure 5C) were significantly shorter at the
higher rectal temperatures, whereas at high skin
temperatures, cycling times were shorter than
those at neutral conditions only when levels of
rectal temperature were the same. One subject
at the neutral condition and three subjects in
the heat failed to show the vasodilatation re-
sponse,

Converted scores of the manual performance
tests, together with the standard errors are shown
in Table III. These scores were analyzed by
a test of significant differences between means
of paired data for all possible combinations of
T, and T,.

Placing the pegs was independent of body
thermal state, but the highest scores for turning
the pegs and for assembling the washers and
rivets were found at neutral skin temperatures
when rectal temperatures were high. Scores for
disassembling were also higher when the body
was warm, but were less dependent on internal
body temperature. Motor coordination scores
were statistically higher in the heat, but subjects
in the cold performed better than those with
neutral T, and low T,.

Values of mean sweat rate were 12.04 g/kg
during the morning exposures, and 15,38 g/kg
during the afternoon, but there was no significant
difference between the two exposures at or below
the 5% level of probability (p<.10>.05).

III. DISCUSSION

The data of this experiment indicate that the
degree of proficiency of manual performance is
governed by the interrelationships among the
central thermal state, the peripheral thermal
state, and the complexity of the task.

The hand placing tests, requiring only coarse
movements of the hands and arms, were inde-
pendent of thermal state, but hand turning scores,
which involved more discreet use of the hand
and fingers, were improved only when T, and T,
were maintained at high levels. Assembling the
washers and rivets, which required fine coordi-
nation of the fingers, was best performed in a
thermally neutral environment. Profuse sweat-
ing at 46°C, and the frequent bouts of shivering
observed at 10°C were possible factors contribut-
ing to impaired kinesthetic sensitivity in these
environments. Disassembling the washers and
rivets was less exacting and although scores were
somewhat better at the neutral and hot condi-
tions they showed little difference from the
thermal state in the cold. Bartlett and Gronow’,
studied dexterity in clothed men at ambient
temperatures of —10°C and also found that
screwing and unscrewing bolts into a nut was
more difficult than a peg placing test.

Scores of the motor coordination test were
significantly higher in the heat than in neutral
or cold conditions, but subjects in the cold scored
higher than those with neutral skin temperature
and low T,. Fox and his coworkers® reported
that when body temperature was raised to 38.5°C,

Taste III. Converted Mean Scores of Performance Tests
n=6
Ambient Hand Deaterity Finger Deaterity Motor
Temperature Place Turn Assemble Disassemble | Coordination
AM 26+5.6 BT7+28 2945.0 BT£I5 11843,7
me PM 164.1 543.7 145.5 522.7 115+9.0
AM 2346.5 642.0 41461 61+15 104+6.0
“ere PM 2843.6 T1426 5143.5 +23 119+8,2
AM 20+5.9 T4416 28+6.2 6O+16 128+6.4
ae PM 275.0 2438 4524.5 6542.4 182454



Ts developed by Burton*. Cold-induced vasodil-
atation (CIVD)* consisted of measuring changes
in finger temperature after immersing the right
‘index finger for 20 minutes into a mechanically
stirred bath to a level midway between the distal
and middle joints.. Temperature was monitored
by a No. 40 gauge copper-constantan thermo-
couple attached to the tip of the finger with a
single layer of plastic tape, and was recorded
by a Varian recorder.

Hand and finger dexterity and motor coordi-
nation were determined from parts of the General
Aptitude Test Battery, developed by the United
States Department of Labor, Figure 1 shows
the peg board for the two-part hand dexterity
test. The first part (Figure 1A) consisted of
placing pegs from the holes at the top of the
board to corresponding holes in the lower part
of the board as quickly as possible in 15 seconds.
In the second part of the test (Figure 1B) the

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LEFT HANDED

B

Ficure 1. Hand dexterity test. (A) Pegboard and
begs for placing test. (B) Correct direction for turn-
ing peg with one hand in peg turning test.

RIGHT HANDED

subject picked up a peg, turned it over with one
hand, and put it back into the same hole. A
practice trial was followed by three test. trials
of 30 seconds each. Scores were the total number
of pegs placed or turned for the three test trials.

The finger dexterity test is shown in Figure 2,
and was also in two parts. It’ consisted of a
board with two sets of holes, the upper set con-
taining metal rivets (Figure 2A). A metal rod
strung with washers was attached to one side
of the board. The subject assembled the rivets
and washers, then inserted as many as possible
into the corresponding holes at the lower part
of the board within 90 seconds (Figure 2B).
The second part consisted of disassembling and
replacing as many washers and rivets as possible
in 60 seconds. One practice trial was allowed
before the test trial. Scores were the number of
rivets and washers successfully assembled or dis-
assembled within the given time periods. The
motor coordination test (Figure 2C) consisted
of making three lines in a square as rapidly as
possible. Two 10-second practice trials were fol-
lowed by a single test trial for 60 seconds and
scores were the total number of squares contain-
ing the lines. A schedule of events during an
exposure is given in Table II.

Taste II. Schedule of Events
Time, Min.
6-30 Hookup, sit quietly; T,, T,, HR, RR at 0, 15,
and 30 min.
31-75 CIVD measurements; T,, T,, HR, RR at 45, 60,
and 75 min.

76-105 Hand, finger dexterity, and motor coordination
tests; T,, T,, HR, RR at 90 and 105 min,

106-120 Sit quietly; T,, T,, HR, RR at 120 min. End
exposure,

Each subject, wearing only shorts, was instru-
mented in an air conditioned dressing room
maintained at 25°C and adjacent to the climatic
chamber. The men were weighed prior to ex-
posure, and those scheduled for 46°C were
weighed again after exposure to determine sweat
output.

II. RESULTS

Figure 8 shows changes in RR, HR, T., Ty
and T, through the time for the three ambient
conditions studied. An analysis of variance®®
comparing neutral conditions with cold showed
that T,, T,, T,, and HR were significantly dif-


THE EFFECTS OF BODY THERMAL STATE ON
MANUAL PERFORMANCE

Efficient manual performance of aviation per-
sonnel concerned with aircraft repair and main-
tenance, and of aircrews to some extent, may
depend on the interrelationships between internal
and peripheral body temperature, the body
thermal state. Environmental temperature is the
principal stressor, and departure from a com-
fortable ambient temperature in which the body
is thermally neutral to severe conditions of heat
or cold may impair performance of aviation
tasks requiring a high degree of hand and finger
dexterity or motor coordination.

Physiological responses of humans to whole
body and peripheral changes in ambient condi-
tions have been studied extensively by a wide
variety of methods, depending on the type of
information desired.***#8° Several investiga-
tors have related whole body temperature to
physiological responses of hands and fingers to
describe the changes in manual perform-
ance.#1015.24 Emphasis has been on cold exposure,
and results were often complicated by protective
clothing or by environmental conditions which
did not permit adequate and separate assessment
of internal body temperature and skin temper-
ature.

This experiment proposes to relate manual
performance to the thermal state of semi-nude
men exposed to cold, thermally neutral, and hot
environments. Performance is evaluated in

terms of changes in the body thermal state, which
include the central thermal state, as measured
by internal body temperature, and the peripheral
state, as reflected by average skin temperature,
hand temperature, and cold-induced vasodilat-
ation of the finger.

I, METHODS

‘Thirty-six young men, chosen at random, were
exposed in pairs for 2 hours to environmental
temperatures of 10°C (50°F) +1°, 26.7°C (80°F)
+19, or 46°C (115°F)+1°. Relative humidities
were 502% at 10° and 26.7°C, and 40+3% at
46°C. Physical characteristics are shown in
Table I. Experiments at these conditions were
conducted in the early morning, when rectal
temperature (T;) was lowest, and in the early
afternoon when T, was relatively high’?". T,
was determined by a bridge and a calibrated
thermistor probe inserted 10 cm into the rectum,
heart rate (HR) by electrocardiogram leads, and
respiratory rate (RR) with a mercury strain
gauge plethysmograph. All three were recorded
on a six-channel Grass recorder. Measurements
of skin temperatures were made with a Stoll-
Hardy radiometer (Model H14)* calibrated
with a Leslie Cube at each of the three ambient
temperatures. Average skin temperature (T.)
was calculated from the seven-point system of
Hardy and DuBois"s, and average body tempera-
ture (T;) from the equation: T,=0.65 T, +0.85

‘Pate I. Physical characteristics of men exposed to three environmental conditions and
at two times of day

Height, om Weight, kg Age, Yr.
Cold a.m. 178.9(173.4-182.9) 77.12 (62.79-87.26) 22(19-25)
10°C p.m. 173.3 (167.0-183.5) 67.43 (54.93-78.12) 22(21-27)
Neutral am, 181.4(177.8-184.8) 75.70 ( 67.50-92.18 ) 22(18-29)
26.7°C pam, 175.2 (169.5-180.3) 74.27 (68.21-97.93) 22 (21-24)
Hot a.m. 183.2 (175.9-188.6) 82.62 (71.90-102.75) 23 (19-29)
46°C p.m, 180.7(174.0-189.2) 79.04 (68.99-86.09 ) 22(19-24)
TOTALS (N=386) 178.8 (167.0-189.2) 76.03 (54.93-102.75) 22 (18-29)

‘Values.are means; ranges are shown in parentheses.

1



ACKNOWLEDGEMENTS

The authors express their appreciation to Dr. Thomas Adams of Michi-
gan State University, who suggested this experiment; to Mr. Orbin Echols,
of the Oklahoma Employment Security Commission for the loan of the

manual performance equipment; and to Miss Betty Gatliff, of CAMI, for
the technical illustrations.

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