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Relation of movement aftereffect duration to interpolated darkness intervals
Life Sciences No . 6, pp . 239-242, 1962 " Great Britain .
Pergamon Press Ltd .
Printed in
RELATION OF MOVEMENT AFTEREFFECT DURATION TO INTERPOLATED DARKNESS INTERUALS~ Irwin M. Spigel University of Pittsburgh School of Medicine and Western Psychiatric Institute (Received 4 May 1962)
PSYCHOPHYSIOLOGICAL investigation of perseverative processes has heretofore been confined largely to problems of learning . l
It appears that a perceptual di-
mension may be made available for a more versatile experimental inquiry into the nature of such activity . The negative aftereffect of visually perceived repetitive pattern movement was employed for the current investigation .
While this form of apparent movement
has been extensively studied and the involved neural events only vaguely understood, the current exploration made use of a recently determined dimension of aftereffect experience .
This is the inhibition of the decay of the aftereffect
as a consequence of contour-free post-exposure stimulation .
In a previous study2
the author found that the interpolation of a period of darkness following exposure of Ss to repetitive pattern movement brought about the inhibition of the normal rate of decay of the negative aftereffect .
In further research, the
author3 utilized the decay inhibition to demonstrate support for central mediation of movement aftereffect phenomena .
It was possible that this inhibitory
manifestation reflected an underlying storage mechanism and that by manipulation of the interpolated darkness interval, the form of the perseverative function could be ascertained . Fifty college students, 25 males and 25 females,
served as Ss .
Because of
individual differences in aftereffect perception, the reference for each S was his or her mean aftereffect duration for five preliminary trials .
These
` This report is based on portions of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, at Temple University, January, 1962 . 239
RELATION OF MOVEMENT AFTEREFFECT DURATIOiu
240
No .b
consisted of 30-second periods of binocular exposure to a rotating (10 -_~v ;`min) disc containing a black-and-white radial pattern . was 15 040' .
The visual angle subtended
On the first trial, Ss were asked merely to report what movem :,t,
and the direction of any movement, they perceived at the cessation of rotation . If the negative aftereffect (apparent movement in the direction opposite to that of rotation) was described by S,
he or she qualified for the experiment .
Follow-
ing this, six additional trials were administered and S instructed to press a switch at his position when he no longer perceived the reverse movement of the disc .
This operation stopped a chronoscope which had started at the termination
of objective rotation . the six timed trials .
S's mean aftereffect was computed from the last five of Ss were then assigned to one of five groups - with five
males and five females in each .
Assignment was carried out so as to yield
equivalence of the five groups with reference to the amount of aftereffect perceived in the preliminary series . On their second appearance two days later, each S was exposed to 30 sec of pattern rotation, then placed in darkness for a pre-set interval, and finally re-exposed to the stationary pattern with the instruction to press the switch when he no longer perceived the reverse movement .
Ss in Group I were kept in
post-movement darkness for a period of time equal to their mean aftereffect duration .
Ss in Groups II, III, IV and V were given post-exposure intervals of
darkness equal to 1 .5, 2 .0, 2 .5 and 3 .0 times their mean aftereffect duration respectively .
Five such trials were administered to all Ss, and the mean of the
last four used to compute the residual mean aftereffect duration for each S . The equivalence of the five groups with regard to preliminary mean aftereffect duration was confirmed by the non-significant F ratio obtained (F = 0 .018, df = 454) "
The F ratio for residual mean aftereffect duration following differ
ential intervals of darkness for each group after 30 sec of rotation (F = 2 .69, df = 445) was significant at less than the 0 .05 level .
Significant t ratios
were obtained between the means for Groups I and IV, I and V,
and II and V .
The function relating residual aftereffect duration to multiples of S's
No .6
RELATION OF MOVEMENT AFTEREFFECT DURATION
241
mean aftereffect time in post-rotation darkness appeared to be linear, and is depicted in Fig . 1 .
A least-squares fit yielded the equation : T = 8 .94 - 2 .22 M,
where T is the residual aftereffect in seconds, and M, the multiple of the normally determined mean aftereffect following exposure to the rotating pattern . N
C O N C_
v V
o~ t
â v N
0
I .0
I .5 2 .0 2 .5 3 .0 Multiple of Mean Aftereffect in Darkness FIG . 1 Function relating residual aftereffect to multiples of mean aftereffect duration in post-exposure darkness .
Thus it may be inferred that the decay of the aftereffect is a linear function of multiples of the duration of one's mean aftereffect in post-exposure darkness .
Earlier investigation4 had revealed inhibition of the aftereffect
decay when both darkness and homogeneous illumination were interposed in the post-exposure period .
From this it had been inferred that it was not darkness
as such, but the absence of contour in the visual field during the post-rotation interval, that was the sufficient condition for the inhibition of the aftereffect decay .
242
RELATION OF MOVEMENT AFTEREFFECT DURATION
No .6
It appeared from the current determinations that this inhibition was relinquished lawfully with regard to individual propensities . of the aftereffect emerged as most demanding of attention .
The persistence
It was only after Ss
had experienced roughly twice their mean aftereffect duration in darkness that the decay reached 50 per cent .
Even after three times their mean in darkness,
approximately 25 per cent of the illusory movement remained . If either sharply negative or positive acceleration was evident in the function, some stepwise gating mechanism might be suspected of operating .
But
the obtained relationship argues for continuity in the loss or dissipation of the apparent movement during the post-exposure period of contour-free stimulation . It is believed that electrophysiological recording techniques may be brought to bear on movement aftereffect investigation with both humans and animals to provide additional insight into perseverative perceptual phenomena and the neural processes and storage functions which underlie them .
Further, change in the
form of the reported functional relationship may be studied as the dependent variable in psychopharmacological investigations involving central excitants or depressants .
Conversely, with drugs of known sites of action, changes in the
function can provide clues to the locus of neural mechanisms which subserve the aftereffect phenomena . References 1.
S .E . GLICKMAN, Psvchol . Bull . 58, 218-233 (1961) .
2.
I .M . SPIGEL, J . Psvchol . 50, 209-210 (1960) .
3.
I .M . SPIGEL, J . Gen . Psvchol . in press (1962) . I .M . SPIGEL, J . Psvchol . i n press (1962) .
Pergamon Press Ltd .
Printed in
RELATION OF MOVEMENT AFTEREFFECT DURATION TO INTERPOLATED DARKNESS INTERUALS~ Irwin M. Spigel University of Pittsburgh School of Medicine and Western Psychiatric Institute (Received 4 May 1962)
PSYCHOPHYSIOLOGICAL investigation of perseverative processes has heretofore been confined largely to problems of learning . l
It appears that a perceptual di-
mension may be made available for a more versatile experimental inquiry into the nature of such activity . The negative aftereffect of visually perceived repetitive pattern movement was employed for the current investigation .
While this form of apparent movement
has been extensively studied and the involved neural events only vaguely understood, the current exploration made use of a recently determined dimension of aftereffect experience .
This is the inhibition of the decay of the aftereffect
as a consequence of contour-free post-exposure stimulation .
In a previous study2
the author found that the interpolation of a period of darkness following exposure of Ss to repetitive pattern movement brought about the inhibition of the normal rate of decay of the negative aftereffect .
In further research, the
author3 utilized the decay inhibition to demonstrate support for central mediation of movement aftereffect phenomena .
It was possible that this inhibitory
manifestation reflected an underlying storage mechanism and that by manipulation of the interpolated darkness interval, the form of the perseverative function could be ascertained . Fifty college students, 25 males and 25 females,
served as Ss .
Because of
individual differences in aftereffect perception, the reference for each S was his or her mean aftereffect duration for five preliminary trials .
These
` This report is based on portions of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, at Temple University, January, 1962 . 239
RELATION OF MOVEMENT AFTEREFFECT DURATIOiu
240
No .b
consisted of 30-second periods of binocular exposure to a rotating (10 -_~v ;`min) disc containing a black-and-white radial pattern . was 15 040' .
The visual angle subtended
On the first trial, Ss were asked merely to report what movem :,t,
and the direction of any movement, they perceived at the cessation of rotation . If the negative aftereffect (apparent movement in the direction opposite to that of rotation) was described by S,
he or she qualified for the experiment .
Follow-
ing this, six additional trials were administered and S instructed to press a switch at his position when he no longer perceived the reverse movement of the disc .
This operation stopped a chronoscope which had started at the termination
of objective rotation . the six timed trials .
S's mean aftereffect was computed from the last five of Ss were then assigned to one of five groups - with five
males and five females in each .
Assignment was carried out so as to yield
equivalence of the five groups with reference to the amount of aftereffect perceived in the preliminary series . On their second appearance two days later, each S was exposed to 30 sec of pattern rotation, then placed in darkness for a pre-set interval, and finally re-exposed to the stationary pattern with the instruction to press the switch when he no longer perceived the reverse movement .
Ss in Group I were kept in
post-movement darkness for a period of time equal to their mean aftereffect duration .
Ss in Groups II, III, IV and V were given post-exposure intervals of
darkness equal to 1 .5, 2 .0, 2 .5 and 3 .0 times their mean aftereffect duration respectively .
Five such trials were administered to all Ss, and the mean of the
last four used to compute the residual mean aftereffect duration for each S . The equivalence of the five groups with regard to preliminary mean aftereffect duration was confirmed by the non-significant F ratio obtained (F = 0 .018, df = 454) "
The F ratio for residual mean aftereffect duration following differ
ential intervals of darkness for each group after 30 sec of rotation (F = 2 .69, df = 445) was significant at less than the 0 .05 level .
Significant t ratios
were obtained between the means for Groups I and IV, I and V,
and II and V .
The function relating residual aftereffect duration to multiples of S's
No .6
RELATION OF MOVEMENT AFTEREFFECT DURATION
241
mean aftereffect time in post-rotation darkness appeared to be linear, and is depicted in Fig . 1 .
A least-squares fit yielded the equation : T = 8 .94 - 2 .22 M,
where T is the residual aftereffect in seconds, and M, the multiple of the normally determined mean aftereffect following exposure to the rotating pattern . N
C O N C_
v V
o~ t
â v N
0
I .0
I .5 2 .0 2 .5 3 .0 Multiple of Mean Aftereffect in Darkness FIG . 1 Function relating residual aftereffect to multiples of mean aftereffect duration in post-exposure darkness .
Thus it may be inferred that the decay of the aftereffect is a linear function of multiples of the duration of one's mean aftereffect in post-exposure darkness .
Earlier investigation4 had revealed inhibition of the aftereffect
decay when both darkness and homogeneous illumination were interposed in the post-exposure period .
From this it had been inferred that it was not darkness
as such, but the absence of contour in the visual field during the post-rotation interval, that was the sufficient condition for the inhibition of the aftereffect decay .
242
RELATION OF MOVEMENT AFTEREFFECT DURATION
No .6
It appeared from the current determinations that this inhibition was relinquished lawfully with regard to individual propensities . of the aftereffect emerged as most demanding of attention .
The persistence
It was only after Ss
had experienced roughly twice their mean aftereffect duration in darkness that the decay reached 50 per cent .
Even after three times their mean in darkness,
approximately 25 per cent of the illusory movement remained . If either sharply negative or positive acceleration was evident in the function, some stepwise gating mechanism might be suspected of operating .
But
the obtained relationship argues for continuity in the loss or dissipation of the apparent movement during the post-exposure period of contour-free stimulation . It is believed that electrophysiological recording techniques may be brought to bear on movement aftereffect investigation with both humans and animals to provide additional insight into perseverative perceptual phenomena and the neural processes and storage functions which underlie them .
Further, change in the
form of the reported functional relationship may be studied as the dependent variable in psychopharmacological investigations involving central excitants or depressants .
Conversely, with drugs of known sites of action, changes in the
function can provide clues to the locus of neural mechanisms which subserve the aftereffect phenomena . References 1.
S .E . GLICKMAN, Psvchol . Bull . 58, 218-233 (1961) .
2.
I .M . SPIGEL, J . Psvchol . 50, 209-210 (1960) .
3.
I .M . SPIGEL, J . Gen . Psvchol . in press (1962) . I .M . SPIGEL, J . Psvchol . i n press (1962) .