September 2005
Volume 5, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2005
Predicting the orientation of invisible stimuli from activity in human primary visual cortex
Author Affiliations
  • John-Dylan Haynes
    Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London/UK, and Institute of Cognitive Neuroscience, University College London, London/UK
  • Geraint Rees
    Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London/UK, and Institute of Cognitive Neuroscience, University College London, London/UK
Journal of Vision September 2005, Vol.5, 221. doi:10.1167/5.8.221
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      John-Dylan Haynes, Geraint Rees; Predicting the orientation of invisible stimuli from activity in human primary visual cortex. Journal of Vision 2005;5(8):221. doi: 10.1167/5.8.221.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

It has been proposed that activity in human primary visual cortex (V1) is necessary but not sufficient for conscious awareness, but direct physiological evidence for the activation of human V1 in the absence of awareness has been elusive. Here, we used functional MRI to measure activity in V1 while participants viewed masked and invisible orientated gratings. Remarkably, when participants were unable to report the orientation of a masked grating they were viewing, we could nevertheless predict its orientation significantly better than chance, based only on a single brief measurement of activity from their primary visual cortex. This was achieved by using multivariate pattern-recognition to substantially improve the ability to detect orientation signals in V1 (see also Kamitani & Tong, VSS 2004). Thus, activity in primary visual cortex conveys orientation-specific information that is inaccessible to conscious report. Orientation can therefore be represented unconsciously in V1, suggesting that information must be relayed to another region of the brain to be represented in conscious experience.

Haynes, J.-D. Rees, G. (2005). Predicting the orientation of invisible stimuli from activity in human primary visual cortex [Abstract]. Journal of Vision, 5(8):221, 221a, http://journalofvision.org/5/8/221/, doi:10.1167/5.8.221. [CrossRef]
Footnotes
 This work was funded by the Wellcome Trust.
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