On the "blindness" of blindsight: What is the evidence for phenomenal awareness in the absence of primary visual cortex (V1)?

A lesion to primary visual cortex (V1) abolishes all phenomenal awareness while unconscious visual functions can remain, leading to the view that V1 is crucial for generating visual consciousness. However, since the early 20th century, controversial reports have described phenomenal awareness in patients with V1 lesions, including selective sparing of motion awareness, hemianopic completion, and visual aftereffects. Recent successful attempts to induce visual qualia with noninvasive brain stimulation are also reviewed. This critical review discusses the implications of these findings for theoretical understanding of phenomenal awareness.

Study at a glance

Abstract

Blindsight has been central to theories of phenomenal awareness; that a lesion to primary visual cortex (V1) abolishes all phenomenal awareness while unconscious visual functions can remain has led to the view that this region plays a crucial role in generating visual consciousness. However, since the early 20th century, there have been reports, many of which controversial, of phenomenal awareness in patients with V1 lesions. These reports include selective sparing of motion awareness, hemianopic completion and visual aftereffects. More recently, there have been successful attempts of inducing visual qualia with noninvasive brain stimulation. Here we critically review this evidence and discuss their implications to theoretical understanding of phenomenal awareness.