Speaker: Ian Phillips, Johns Hopkins University
Title: Bewitched by Blindsight
Textbooks tell us that, across a range of paradigms and conditions, perception parts ways with consciousness. The poster child is blindsight: a neuropsychological disorder defined by residual visual function following destruction of primary visual cortex. Blindsight is especially striking because residual visual function apparently includes capacities for voluntary discrimination in the total absence of awareness. Together with other neuropsychological disorders (e.g.,hemineglect and visual form agnosia) and studies of neurotypical vision (e.g.,under inattention or suppression), blindsight has revolutionized our thinking about visual consciousness, seemingly revealing a dramatic disconnect between performance and awareness, and motivating diverse theories of the neural and cognitive basis of consciousness. Counter to this orthodoxy, I’ll argue that blindsight is in fact severely and qualitatively degraded but nonetheless conscious vision. This residual conscious vision appears unconscious only because of conservative and unstable response criteria. A series of psychophysical and functional arguments against this interpretation are answered. And a range of consistent behavioral and first-person evidence is presented. This evidence helps answer the question of what it is like to have blindsight, as well as to account for the conservative and selectively unstable response criteria exhibited by patients. In closing, I’ll consider what lessons we can learn for the study of consciousness more generally, both in clinical and neurotypical vision.
Ian Phillips is currently Bloomberg Distinguished Professor of Philosophy and Brain Sciences at Johns Hopkins University, where he is cross-appointed in the William H. Miller, III Department of Philosophy, and the Department of Psychological and Brain Sciences. Previously, he has taught at Princeton, Oxford, and University College London (where he obtained his PhD). His primary research interests include: the nature of perception; the scientific study of consciousness; and our experience of time.