Hemifield relative motion bias in adults monocularly enucleated at an early age

A psychophysical study of relative motion discrimination for six subjects monocularly enucleated within 24 months of birth showed no significant difference in their thresholds for detecting relative velocity when compared with age matched control subjects. The study however highlighted a bias for the control group, age matched normals, which is consistent with a hemifield anisotropy for motion in normal observers reported by Smith and Hammond [(1986) Perception, 15, 111-117]. The bias however was found to be reversed for enucleates. This difference and individual differences reported in the Smith and Hammond study are discussed in terms of possible developmental changes which emerge when stereopsis is absent or weak.