Low-Level Phenomenal Vision Despite Unilateral Destruction of Primary Visual Cortex

Authors: Stoerig P.¹; Barth E.²

Source: Consciousness and Cognition, Volume 10, Number 4, December 2001 , pp. 574-587(14)

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Abstract:

GY, an extensively studied human hemianope, is aware of salient visual events in his cortically blind field but does not call this “vision.” To learn whether he has low-level conscious visual sensations or whether instead he has gained conscious knowledge about, or access to, visual information that does not produce a conscious phenomenal sensation, we attempted to image process a stimulus s presented to the impaired field so that when the transformed stimulus T(s) was presented to the normal hemifield it would cause a sensation similar to that caused by s in the impaired field. While degradation of contrast, spatio-temporal filtering, contrast reversal, and addition of smear and random blobs all failed to match the response to a flashed bar s_f, moving textures of low contrast were accepted to match the response to a moving contrast-defined bar, s_m. Orientation and motion direction discrimination of the perceptually matched stimuli [s_m and T(s_m)] was closely similar. We suggest that the existence of a satisfactory match indicates that GY has phenomenal vision. Copyright 2001 Elsevier Science (USA).

Keywords: Key Words: conscious vision; perceptual matching; visual cortex; qualia; access; GY

Language: English

Document Type: Research article

Affiliations: 1: Heinrich-Heine-University, Universitätstraße1, Bldg. 23.03, Düsseldorf, D-40225, Germany 2: Institute for Signal Processing, Medical University of Lübeck, Lübeck, D-23538, Germany

Publication date: 2001-12-01