Blindsight

From Psy3242

Definition

Blindsight is defined by the Oxford Concise Dictionary as "a condition in which the sufferer responds to visual stimuli without consciously perceiving them". Human patients with such a condition often have lost V1 functioning and claim they are blind. In primates and humans, the retina relays its major neural output to the thalamus and then to visual cortex (V1, or striate cortex). When the strait cortex is completely removed or blocked in the brain of a monkey, the animal can still discriminate between certain visual stimuli, though its overall capacity for normal functioning has changed. This is because the output from the eye also reaches various other brain regions in the midbrain and thalamus that often remain intact and undamaged when V1 is completely removed.

History

The history of blindsight stems from a focus on animal research and neuroanatomy, especially in the contrast of human and other primate visual cortex functions. One of the first hypotheses of residual vision in monkeys was made in 1886 by David Ferrier, who removed his subjects' entire visual cortexes and observed the 'blind' monkeys navigating around obstacles. Later, in