Blindsight

Blindsight is a neurological phenomenon in which a person who is cortically blind, having lost conscious vision because of damage to the brain's primary visual cortex, can nonetheless respond to visual stimuli that they report not consciously seeing at all. It occurs because, following damage to the primary visual cortex, other branches of the optic nerve continue to deliver visual information to other brain structures, including the superior colliculus and the pulvinar, which are then able to guide the blindsight responses even though the pathway through the primary visual cortex itself is no longer available. Research further indicates that the thalamic structure called the lateral geniculate nucleus plays a causal role in this kind of visual processing that bypasses the primary visual cortex, relaying visual information directly to higher brain regions along an alternate route. Blindsight is treated as important evidence that visual information can influence and control behavior without ever producing a conscious visual sensation, challenging the assumption that visual perception must become conscious in order to affect what a person does.