Energy model for contrast detection: spatial-frequency and orientation selectivity in grating summation

Velitchko Manahilov, William A. Simpson

Research output: Contribution to journalArticle

Abstract

Models of spatial vision usually assume a ‘front-end’ of spatial-frequency and orientation selective channels. Subthreshold-summation studies have provided some of the strongest support for this notion. We applied a single-channel energy model and a multiple-channels probability-summation model to explore subthreshold-summation phenomena. We measured the contrast thresholds for detection of two superimposed Gabor patches as a function of the spatial-frequency and orientation difference between the components. The stimuli were centred 7.5 deg above the fixation point and were windowed by a Gaussian function with one of two different spatial spreads. We have shown that the spatial-frequency and orientation selectivity in subthreshold summation of Gabor patches is determined by the similarity (cross-correlation) between the stimulus components. A single-channel energy model as well as a multiple-channels probability-summation model could explain the summation data.

Original languageEnglish
Pages (from-to)1547-1560
Number of pages14
JournalVision Research
Volume41
Issue number12
DOIs
Publication statusPublished - 1 Jun 2001

Keywords

  • orientation selectivity
  • vision sciences
  • spatial-frequency selectivity
  • energy model

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