Strength of early visual adaptation depends on visual awareness

doi:10.1073/pnas.0509634103

Strength of early visual adaptation depends on visual awareness

Vanderbilt Vision Research Center and Department of Psychology, Vanderbilt University, 111 21st Avenue South, Nashville, TN 37203

Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved January 30, 2006 (received for review November 5, 2005)

Abstract

We measured visual-adaptation strength under variations in visual awareness by manipulating phenomenal invisibility of adapting stimuli using binocular rivalry and visual crowding. Results showed that the threshold-elevation aftereffect and the translational motion aftereffect were reduced substantially during binocular rivalry and crowding. Importantly, aftereffect reduction was correlated with the proportion of time that the adapting stimulus was removed from visual awareness. These findings indicate that the neural events that underlie both rivalry and crowding are inaugurated at an early stage of visual processing, because both the threshold-elevation aftereffect and translational motion aftereffect arise, at least in part, from adaptation at the earliest stages of cortical processing. Also, our findings make it necessary to reinterpret previous studies whose results were construed as psychophysical evidence against the direct role of neurons in the primary visual cortex in visual awareness.

Footnotes

*To whom correspondence should be addressed. E-mail: randolph.blake{at}vanderbilt.edu
↵ ^†Present address: Department of Psychology, University of Central Arkansas, Conway, AR 72035.
↵ ^‡Present address: Department of Psychology, Graduate Program in Cognitive Science, Yonsei University, Seoul 120-749, Korea.
Author contributions: R.B., D.T., K.V.S., T.A.R., and S.C.C. designed research; R.B., D.T., K.V.S., T.A.R., and S.C.C. performed research; D.T., K.V.S., T.A.R., and S.C.C. analyzed data; and R.B. and D.T. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

V1,

primary visual cortex;

MAE,

motion aftereffect;

TEAE,

threshold-elevation aftereffect.
Freely available online through the PNAS open access option.