Perceptual consequences of visual performance fields: The case of the line motion illusion

Stuart Fuller, Marisa Carrasco

Research output: Contribution to journalArticle

Abstract

Illusory line motion (ILM) is the illusion that a line, preceded by a small dot (cue) near one end, is perceived to shoot out from the dot even though the line is physically presented at once. Does this illusion result from a low-level motion effect, a gradient of exogenous spatial attention, or both? Given that exogenous attention speeds visual processing unequally at isoeccentric cardinal locations (M. Carrasco, A. M. Giordano, & B. McElree, 2004), we hypothesized that the contribution of attention to ILM would follow the same pattern. We characterized psychometric functions of perceived line motion direction, for 1.5° stimuli with varying amounts of physical line motion (8 levels) at four cardinal locations. We used three cue conditions to separate the effects of attention from low-level motion - a single cue to draw focal attention to the stimulus location, a distributed cue with elements near all four possible stimulus locations, and no visual cue. Distributed and single cues generate identical effects along the horizontal meridian, but the effect of the single cue is progressively greater along the vertical meridian, more so at the top location ("North"). We conclude that the low-level motion explanation accounts for the majority of the canonical example of the ILM (line preceded by a single dot) effect used in our study.

Original languageEnglish (US)
Article number13
JournalJournal of vision
Volume9
Issue number4
DOIs
StatePublished - Apr 17 2009

Keywords

  • Attention
  • Motion-2D
  • Spatial vision

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

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