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Claire Miller, Kimron Shapiro, Steven Luck; The effect of competition on early visual ERP components. Journal of Vision 2012;12(9):376. doi: 10.1167/12.9.376.
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Although competition between inputs in early visual areas of the brain is known to be a key determinant in perception (e.g., biased competition, Desimone and Duncan, 1995), many investigators give little thought to this when choosing their stimulus parameters. To study this, we employed the ERP approach in fifteen participants aged 19-33 who were presented with checkerboard stimuli (100 ms duration) to elicit C1, C2 and P1 components. Participants were given the task of responding to infrequent ‘targets’, but the analyses focused on target-absent trials to obtain a measure of competition unaffected by response demands. Stimuli were presented in three randomised conditions: single stimulus, near proximity pairs (0.16° apart) and far proximity pairs (2° apart). Competition predicts a reduced response to a stimulus when presented as part of a pair relative to when presented alone, with greater reduction predicted for pairs that are closer together. Evidence for competition was observed in the C2 wave, likely reflecting feedback into area V1, and the P1 wave, likely reflecting extrastriate cortex. These findings suggest that competition influences sensory encoding. This method provides an empirical means of measuring competitive interactions at specific stages of visual processing, which will make it possible to rigorously test predictions about the effects of competition on perception, attention, and working memory.
Meeting abstract presented at VSS 2012
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