Stimulus similarity modulates competitive interactions in human visual cortex

Diane M. Beck, Sabine Kastner

Research output: Contribution to journalArticlepeer-review


When multiple visual stimuli are simultaneously presented in a neuron's receptive field, they often interact with each other by mutually suppressing their visually evoked responses, suggesting that multiple stimuli present at the same time in the visual field compete for neural representation. Previous research has shown that these suppressive interactions can be biased by top-down influences such as spatially directed attention, as well as by the bottom-up factor of visual salience. Using fMRI, we asked whether competitive interactions might also be modulated by other bottom-up factors and tested the effects of stimulus similarity. Specifically, we found that suppressive interactions in area V4, measured by comparing activity evoked by simultaneous (potentially competing) and sequential (noncompeting) presentations, were reduced when four items were identical relative to when the four items differed in color and orientation. Such a result is consistent with the prediction that competition is more likely to occur between groups than within a group.

Original languageEnglish (US)
Article number19
JournalJournal of vision
Issue number2
StatePublished - Aug 27 2007


  • Attention
  • Competition
  • Crowding
  • Visual cortex
  • fMRI

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems


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