Human perception of angular acceleration during and after rotatio

Clark, B.

English

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FACTORS INFLUENCING THE PERCEPTION OF ANGULAR 
ACCELERATION IN MAN 
Second Semi-Annual Status Report on NASA Grant No. NGR 05-046-002 
August 1968 
Principal Investigator: Brant Clark 
San Jose State College 
Department of Psychology 
San Jose, California 95114 
2 
INTRODUCTION 
I 
This cooperative research p ro jec t  has been conducted as a 
co l labora t ive  research e f f o r t  between t h e  Psychology Department of 
San Jose  S t a t e  College and Ames Research Center. Spec i f i ca l ly ,  t he  
research has been ca r r i ed  out i n  c lose  co l labora t ion  with John D. 
Stewart of t he  Man-Machine In tegra t ion  Branch. The development of 
t he  Man-Carrying Rotation Device has made poss ib le  s tud ie s  of t he  
perception of r o t a t i o n  under very ca re fu l ly  cont ro l led  conditions.  
It w a s  t he  purpose of t h i s  cooperative research e f f o r t  t o  exp lo i t  t he  
capab i l i t y  of t he  MCRD t o  produce p rec i se  angular acce lera t ions  f o r  
varied intervals of t i m e  using t h e  methods which have been developed 
a t  Ames Research Center t o  inves t iga t e  the  perception of r o t a t i o n  
i n  man. The ind iv idua ls  carrying out t h i s  work were t h e  p r inc ipa l  
i nves t iga to r  and M r .  Stewart a s s i s t e d  by three  research a s s i s t a n t s  
who are candidates f o r  t he  master's degree i n  Psychology a t  San Jose 
State College. These are Richard L. Doty, Richard D. Parsons, and 
Steven L .  Dqckstader. M r .  Dockstader replaced M r .  Doty i n  Ju ly  
when M r .  Doty l e f t  t o  undertake graduate work f o r  t he  Ph.D. i n  
Psychology a t  Michigan State University. 
3 
PURPOSES OF THE RESEARCH 
The Perception of Rocation in Normal Men 
The objective of this research was to investigate the nature 
of the perception of angular acceleration in normal men during and 
following rotation. Whereas the majority of the earlier studies have 
been primarily concerned with physical models and the physiological 
mechanisms of the semicircular canals, this project has been concerned 
with man's subjective reactions to angular acceleration. Using the 
MCRD and a psychophysical method developed at Ames Research Center, 
work has been carried out to determine the range of sensitivity for 
anguiar acceleration in normal men. In addition, the effects of 
duration of stimulation, presence of visual targets in the field, axis 
of rotation and suprathreshold stimulation by angular acceleration 
have been studied, The work has resulted in reports at two meetings; 
two studies are in the final stages of data collection and preparation 
of the reports is well advanced; and one thesis study is complete and 
submitted for publication while the other is in the final stage of 
writing. 
of completion will indicate the degree to which our objectives have 
been achieved. 
The following summary of work completed and in final stages 
4 
SUMMARIES OF RESEARCH FINDINGS 
1. Thresholds -- f o r  t h e  perception - of angular acce lera t ion  
determined -- i n  a p rec i s ion  r o t a t i o n  device. Clark, B. ,  & Stewart, J . D .  
A paper presented a t  t h e  annual meeting of the  Aerospace Medical Associ- 
a t i o n ,  M i a m i ,  F lor ida ,  May 6-9, 1968. 
Summary 
The purpose of t h i s  study w a s  t o  determine the  s e n s i t i v i t y  of normal 
men t o  angular acce le ra t ion  using the  Ames Man-Carrying Rotation Device 
(MCRD). The MCRD is a one-degree-of-freedom simulator which r o t a t e s  
about a vertical axis up t o  45 rpm with continuous angular acce lera t ion  
va r i a t ions  up t o  30 /sec . The acce lera t ions  can be programmed and 
measured i n  0.01°/sec2 s t eps  with rise t i m e s  of t he  order of 0 . 1  sec. 
The MCRD is e s s e n t i a l l y  f r e e  of v ib ra t ions  perceived by the  observer a t  
the  low v e l o c i t i e s  used, and he is unable t o  d e t e c t  when he accelerates 
through zero ve loc i ty .  The observer sat e r e c t  i n  darkness a t  the  c e n t e r .  
of r o t a t i o n  and reported the  d i r ec t ion  of r o t a t i o n  f o r  angular accelera- 
t i ons  of 10 sec. duration. Accelerations w e r e  presented using a forced 
choice random, double staircase method. This procedure determined 
thresholds with v e l o c i t i e s  which r a r e l y  exceeded 2-3 rpm. Thresholds, 
w e r e  computed following a method which earlier s tud ie s  have shown t o  be 
r e l i a b l e  and v a l i d  under t h e  conditions used. Thresholds obtained on 
33 normal men w e r e  found t o  vary between 0.05'and 2.20°/sec 
of 0.42'/sec2 and are lower than those found i n  most earlier s tud ie s  
(Figure 1). 
angular acce lera t ions  applied t o  t h e i r  bodies. This information when i t  
is v e r i d i c a l  can be a cont r ibu t ing  f a c t o r  i n  cont ro l l ing  a i r c r a f t .  
t he  o ther  hand when t h e  information is  not v e r i d i c a l ,  i t  may cont r ibu te  
t o  d i so r i en ta t ion .  
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These da t a  show t h a t  normal men are extremely s e n s i t i v e  t o  
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2. - Some recent  s t u d i e s  on t h e  perception of ro t a t ion .  Clark, B. 
A paper presented a t  the  meeting of t h e  Bira'ny Society, Uppsala, Sweden, 
May 29-30, 1968. 
t he  meeting.) 
(This paper w i l l  be published i n  the  proceedings of 
Summary 
The purpose of t h i s  paper w a s  t o  give a summary of recent  work 
car r ied  out a t  Ames Research Center using the  MCRD t o  r o t a t e  t he  
observers. The paper did th ree  things.  It described t h e  MCRD, 
presented r e s u l t s  of our threshold s t u d i e s ,  and summarized some of 
our work on the  e f f e c t s  of prolonged acce lera t ions  on normal men. 
These s tud ie s  of t h e  perception of r o t a t i o n  give support t o  earlier 
s tud ie s  which have shown t h a t  t he  perception of r o t a t i o n  is a highly 
complex process. 
dependent upon t h e  i n t e r a c t i o n  of complex transducer mechanisms i n  the  
receptors as w e l l  as highly complex c e n t r a l  nervous system processes. 
The da ta  on thresholds suggest t h a t  normal men are even more s e n s i t i v e  
t o  angular acce lera t ion  under optimum t e s t i n g  conditions than earlier 
s tud ie s  had shown. This is p a r t i c u l a r l y  t r u e  when the  oculogyral 
i l l u s i o n  is used as the  ind ica tor  of s e n s i t i v i t y .  
longed acce lera t ion  described t h e  complete cycle of response increase  
and dec l ine  during prolonged constant acce lera t ion  and an a f t e r e f f e c t  
having a similar p a t t e r n  which occurred when t h e  acce le ra t ion  w a s  reduced 
t o  zero. 
acce le ra t ions  notably a waxing and waning of t h e  perception of ro t a t ion .  
These r e s u l t s  have s igni f icance  i n  r e l a t i o n  t o  a general  theory of 
ves t ibu la r  function. 
The da ta  show t h a t  t h e  perception of r o t a t i o n  is  
The s tud ie s  of pro- 
Highly complex e f f e c t s  occurred during the  cons tan t ly  increasing 
7 
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The effect - of duration - of stimulus presentation upon the 3.  -
angular acceleration threshold of man. Doty, R.L. Thesis, Department 
of Psychology, San Jose State College, June 1968. (A shorter version 
has been submitted for publication.) 
Summary 
This study is concerned with the effects of the duration of angular 
acceleration on man's sensitivity to rotation as indicated by his per- 
ception of the oculogyral illusion. 
stimulus as a product of acceleration x time in producing vestibular 
effects. In order to investigate these problems, oculogyral illusion 
thresholds for 10 men were determined in the Ames MCRD. Thresholds 
were measured for stimulus durations of 0.50, 1.00, 1.50, 3.00, and 
6.00 sec. by a random, double staircase procedure. Mean oculogyral 
illusion thresholds ranged from 0.10 to 0.62O/sec and varied inversely 
with the duration of the stimulus (Figure 2). 
times duration of angular acceleration was found to be a significant 
increasing linear function of the duration of the stimulus within the 
limits of the durations used and not constant as earlier data suggest. 
It is also concerned with the 
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The product of acceleration 
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4 .  Magnitude estimates of t he  oculogyral i l l u s i o n  dur ing  - and 
following angular acce lera t ion .  Parsons, R.D. Thesis, San Jose  
S t a t e  College, August 1968. 
Summary 
This experiment inves t iga ted  the  influence of r o t a t i o n  on normal 
men using t h e  i l l u s o r y  motion of a v i s u a l  t a r g e t  i n  darkness t o  ind ica t e  
the  e f f e c t .  Suprathreshold angular acce lera t ions  of s eve ra l  magnitudes 
and durations were used as t h e  s t imu l i  t o  produce the  oculogyral i l l u -  
s ion ,  a v isua l -ves t ibu lar  phenomenon. Ten observers gave magnitude 
estimates of the  oculogyral i l l u s i o n  while they were ro ta ted  i n  t h e  
MCRD t o  produce angular acce lera t ions  about t he  vertical a x i s  of t he  
head. 
a t ions  (2O, 3 O ,  6O, and 9 / sec  ) and four times (1, 3,  6, and 9 sec.)  
w a s  used, and add i t iona l  trials of constant ve loc i ty  served as a con t ro l  
f o r  v i s u a l  au tokines is .  Magnitude estimates, averaged across replica- 
t i ons  and observers, w e r e  p lo t t ed  aga ins t  time t o  form group curves. 
Analyses of variance were a l s o  performed on f i r s t  e f f e c t  and a f t e r e f f e c t  
measures. Systematic changes i n  magnitude estimates were revealed both 
during and following a l l  acce lera t ions  (Figure 3 ) .  The maximum magnitude 
estimates of t he  f i r s t  e f f e c t  and a f t e r e f f e c t  were found t o  vary d i r e c t l y  
with both duration and i n t e n s i t y  of acce lera t ion .  
e f f e c t  var ied  d i r e c t l y  with i n t e n s i t y ,  and duration of t he  a f t e r e f f e c t  
var ied  d i r e c t l y  with both i n t e n s i t y  and duration of acce lera t ion .  
w a s  a l s o  found t h a t  equal products of acce lera t ion  and t i m e  produced 
c lose  similarities f o r  c e r t a i n  measures of behavioral e f f e c t s .  The 
weight of evidence from t h e  da ta  was found t o  be incons is ten t  with 
a simple torsion-pendulum model of semicircular canal functioning, and 
i t  w a s  suggested t h a t  t h e  discrepancies w e r e  due t o  c e n t r a l  processes. 
A f a c t o r i a l  design cons is t ing  of four constant angular acceler- 
0 2  
Duration of t h e  f i r s t  
It 
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@-O 9 - SEC. ACCELERATION 
H 6- SEC. ACCELERATION 
3 - SEC. ACCELERATION 
M I -SEC, ACCELERATIQN 
W 160 SEC. OF ZERO ACCELERATION 
Figure 3. Maginitude estimates o f  the oculogyral illusion for 10 
normal men f o r  9 sec. of angular acceleration (Parsons, 1968). 
11 
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5. Thresholds -- f o r  t he  - of acce le ra t ion  about 
the  th ree  major body axes. Clark, B. ,  ti Stewart, J.D. A paper t o  be 
presented a t  t h e  Fourth Symposium on t h e  Role of t he  Vestibular Organs 
i n  t h e  Exploration of Space, U. S. Naval Aerospace Medical I n s t i t u t e ,  
Pensacola, Florida,  September 24-26, 1968. 
-- 
Summary 
Since very l i t t l e  da ta  are ava i l ab le  on t h e  s e n s i t i v i t y  t o  r o t a t i o n  
about t h e  various body axes, i t  w a s  t he  objec t ive  of t h e  present study 
t o  determine t h e  thresholds f o r  t h e  perception of angular acce le ra t ion  
about t h e  x-, y-, and z-axes of t h e  body. The observers were 18 normal 
men who were ro t a t ed  i n  t h e  MCRD. 
forced-choice, random, double staircase method, and t h e  order of thres- 
hold determination f o r  t he  x-, y-, and z-axes was  es tab l i shed  by a Lat in  
square procedure r ep l i ca t ed  th ree  times. 
standard deviations w e r e  e s s e n t i a l l y  the  same f o r  t he  x- and z-axes. 
However, t he  mean threshold f o r  t he  y-axis was higher and t h e  ind iv idua l  
d i f fe rences  w e r e  subs t an t i a l ly  g rea t e r  than those f o r  t he  x- and z-axes. 
It is suggested t h a t  these  d i f fe rences  are due t o  psychological f a c t o r s  
r a the r  than t o  d i f fe rences  i n  function of the  semicircular canals when 
placed i n  d i f f e r e n t  pos i t ions  with respect t o  grav i ty .  
Thresholds w e r e  determined using a 
Mean thresholds and t h e i r  
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12 
l e r a t i o n  -- on man: Thresholds for 
the  percept ion  of r o t a t i o n  and the  oculogyral i l l u s i o n .  
& Stewart, J . D .  
f o r  publ ica t ion) .  
Clark, B . ,  -
(This study i s  being prepared t o  be submitted 
This paper is concerned wi th  the  range of s e n s i t i v i t y  
of normal men t o  angular acce lera t ions  associated with passive 
body r o t a t i o n  which occurs i n  simulators,  a i r c r a f t ,  and spacecraf t .  
The s p e c i f i c  purpose of t h e  study w a s  t o  measure man's s e n s i t i v i t y  
t o  angular acce le ra t ion  using t h e  perception of r o t a t i o n  and 
the  perception of t he  oculogyral i l l u s i o n  as indica tors .  Thresholds 
f o r  t h e  perception of r o t a t i o n  about t h e  observer's vertical 
ax i s  have been obtained f o r  50 normal men and comparative d a t a  
on both ind ica to r s  have been obtained on 27. The da ta  show 
c l e a r l y  t h a t  t he  mean threshold f o r  t h e  perception of angular 
acce le ra t ion  is  of t he  order of 0.4'/sec2, but t he re  is a very 
l a r g e  range of s e n s i t i v i t y  from 0.05 t o  2.24O/sec , Thresholds 
f o r  t he  oculogyral i l l u s i o n  were found t o  be less than one 
t h i r d  of those f o r  t h e  perception of r o t a t i o n ,  and t h e  v a r i a b i l i t y  
f o r  t h e  oculogyral i l l u s i o n  w a s  f a r  below t h a t  of t h e  perception 
of ro t a t ion .  Furthermore the  co r re l a t ion  between t h e  thresholds 
f o r  t h e  two ind ica to r s  w a s  not s i g n i f i c a n t l y  d i f f e r e n t  from 
0 2 
zero. 
one threshold,  cannot be predicted from the  o ther .  It a l s o  
suggests t h a t  separa te  sensory systems are involved i n  these  
two ind ica to r s  of ves t ibu la r  s t imula t ion .  
This makes i t  c l e a r  from a practical  point of view t h a t  
13 
7. Autokinesis i n  a r o t a t i n g  simulator.  S t e w a r t ,  J . D .  
(This repor t  is i n  the  preliminary s t ages  of ana lys i s ) .  
The i l l u s o r y  motion of f ixed ,  v i s u a l  ob jec t s  i n  darkness or  
v i s u a l  au tokines is  has been reported f o r  hundreds of years.  It 
has a l s o  been observed under loosely cont ro l led  conditions during 
f l i g h t .  S imi la r ly ,  apparent r o t a t i o n  of a i r c r a f t  and a i r c r a f t  
simulators has been reported f o r  years.  
gyroautokinesis. Although both phenomena are w e l l  known, ne i the r  
has been studied under c a r e f u l l y  controlled laboratory conditions 
i n  a r o t a t i n g  device. Data from con t ro l  trials i n  an earlier 
experiment which produced gyroautokinesis and Parson's (1968) 
da ta  above which reported v i s u a l  autokinesis provide a cont ro l led  
s i t u a t i o n  and are being analyzed i n  d e t a i l .  Preliminary ana lys i s  
suggests t h a t  t h e r e  is a s u b s t a n t i a l  amount of v i s u a l  au tokines is  
and gyroautokinesis under these  conditions. This study should 
i l l u c i d a t e  the  c h a r a c t e r i s t i c s  of these  two i l l u s o r y  e f f e c t s  i n  
simulators and a i r c r a f t  and suggest poss ib le  complications i n  the  
use of motion information i n  t h e  con t ro l  of a i r c r a f t .  
We have ca l l ed  t h i s  


Factors influencing the perception of angular acceleration in man Semiannual status report

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