A case of mind/brain identity

one small bridge for the explanatory gap

William R. Webster

pp. 275-287

in: Synthese 131 (2), 2002.

Abstract

Based on the technique ofpressure blinding of the eye, two types of after-image (AI) were identified. A physicalist or mind/brain identity explanation was established for a negative a AI produced by moderately intense stimuli. These AI's were shown to be located in the neurons of the retina. An illusory AI of double a grating's spatial frequency was also produced in the same structure and was both prevented from being established and abolished after establishment by pressure blinding, thus showing that the location was not more central. The illusory AI was predicted from the knownnon-linearity in the retina and this is the first case of a clear cut type-type identity of a sensation and a neural process. Some implications for the concepts of the explanatory gap between neurology and consciousness and multiple neural realizations of conscious states and topic neutrality are discussed.