VARIETIES OF VISION - FROM BLIND RESPONSES TO CONSCIOUS RECOGNITION

Lesions in consecutive parts of the visual system cause visual deficit s that spare increasingly complex residual functions. Patients with le sions up to and including primary visual cortex can show neuroendocrin e, reflexive, implicit and forced-choice responses to visual stimulati on but no conscious vision. In contrast, patients with lesions in high er visual cortical areas have conscious vision. Its lowest level is th at of phenomenal vision, followed by object vision and recognition. Th ese levels are dissociable. They require the integrity of different pa rts of the system.