Perceptual load alters visual excitability

David Carmel, Jeremy D. Thorne, Geraint Rees, Nilli Lavie

Research output: Contribution to journalArticlepeer-review

Abstract

Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load should affect simultaneous, but not sequential, stimulus presentations, the visual excitability account makes the novel prediction that load should affect detection sensitivity for both simultaneous and sequential presentations. Participants fixated a stimulus stream, responding to targets defined by either a color (low load) or color and orientation conjunctions (high load). Additionally, detection sensitivity was measured for a peripheral critical stimulus (CS) presented occasionally. Increasing load at fixation reduced sensitivity to the peripheral CSs; this effect was similar regardless of whether CSs were presented simultaneously with central stimuli or during the (otherwise empty) interval between them. Controls ruled out explanations of the results in terms of strategic task prioritization. These findings support a cortical excitability account for perceptual load, challenging stimulus competition accounts.

Original languageEnglish
Pages (from-to)1350-1360
Number of pages11
JournalJournal of Experimental Psychology: Human Perception and Performance
Volume37
Issue number5
DOIs
Publication statusPublished - Oct 2011

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