Previous studies have found that the spatial uncertainty of amblyopes
is critically dependent on temporal factors. These studies claim that
the spatial uncertainty is much greater at short exposure durations. W
e have reassessed the effect of exposure duration on the spatial uncer
tainty of normal and amblyopic eyes using a task in which we can compe
nsate for the loss in contrast sensitivity which inevitably occurs as
exposure duration is shortened. Our task involved a three-element alig
nment task, where each of the elements were spatial Gabors at two diff
erent separations. We ensured that our stimuli were always displayed a
t a fixed ratio above contrast detection thresholds at each exposure d
uration. Our results show that for normal subjects, for well separated
equi-visible stimuli, there is only a weak effect of exposure duratio
n. A similar dependence is found for the dominant and amblyopic eyes o
f a group of strabismic amblyopes. Dominant eyes of strabismic amblyop
es show increased spatial uncertainty compared with normal subjects. A
mblyopic eyes of strabismic amblyopes show increased spatial uncertain
ty compared with their dominant fellow eye which is invariant with exp
osure duration. Some subjects show a larger positional deficit at shor
t durations when the stimuli are almost abutting.