Defensive responses to looming visual stimuli in monkeys with unilateral striate cortex ablation

A number of residual visual functions including detection, localization and discrimination of visual stimuli, have been demonstrated in the "blind" fields of monkeys and human patients following damage to striate cortex. We report here that avoidance movements of the head can also be elicited from monkeys with unilateral striate cortex ablations when a "looming" stimulus is presented within the hemianopic and presumably "blind" field. The possible role of the retinofugal projection to superior colliculus in the mediation of these defensive head movements is discussed.