The assessment of motor control in sighting dominance using an illusion decrement procedure

Walls (1951) proposed that perceptual asymmetries between the sighting dominant and the nonsighting dominant eyes were based upon differences in the monitoring of eye movements. The present research explored this hypothesis in the context of an illusion decrement paradigm. Since illusion decrement seems to occur only under conditions of free eye-movement inspection, it was reasoned that any motoric asymmetries would manifest themselves through differences in the rate and extent of decrement. These predictions were partially confirmed. The sighting eye manifested greater illusion decrement, but the effect remained specific to conditions where both eyes were stimulated. In addition, asymmetries in the interocular transfer of illusion decrement were found to favor the sighting dominant eye.