One classic piece of evidence for an efference copy signal of eye posi
tion is that a small, positive afterimage viewed in darkness is percei
ved to move with the eye, When a small stationary reference point is v
isible the afterimage appears to move relative to the reference point,
However, this is true only when the afterimage is localized to a smal
l area, We have observed that when an extended afterimage of a complex
scene is generated by a brief, bright flash it does not appear to mov
e, even with large changes in eye position, When subjects were instruc
ted to maintain their direction of gaze, we observed small saccades (t
ypically <1 deg) and slow drift movements often totalling more than 10
deg over a 30 sec period, When the instructions were to simply inspec
t the extended afterimage, subjects made larger saccades (up to 5 deg)
which were not accompanied by afterimage movement, The smaller moveme
nts observed under the first instructions are greater than those obser
ved in the dark or with small afterimages. When a visible reference is
present with these large afterimages, the afterimage appears stationa
ry, while the reference point appears to move, Eye position was monito
red following the generation of such afterimages. In general, the perc
eived motion of the stationary reference point was in a direction oppo
site to the motion of the eye, Similar drift movements of smaller magn
itude were observed with localized afterimages, but the motion was att
ributed to the afterimage, This suggests that with whole scene afterim
ages, extraretinal information about slow movements and small to moder
ate saccades is absent or suppressed, and that stationarity is assigne
d to the complex scene, This indicates a perceptual disposition to rel
y on visual information (when it is available) for maintaining constan
cy of visual direction, despite substantial changes in eye position, W
e found that changes in gaze as large as 13 deg produced no change in
reported position of the large scene afterimage. When a small, station
ary reference light was present it appeared to move in the afterimage
scene in a way consistent with the recorded eye movements, When observ
ers attempted to maintain their direction of gaze, most of the eye mov
ements were slow drift, with occasional small saccades, When the instr
uction to hold gaze was relaxed, larger saccades up to about 5 deg wer
e observed which were not accompanied by afterimage movement.