Directional shifts in the barber pole illusion: effects of spatial frequency, spatial adaptation, and lateral masking

Vis Neurosci. 2006 Sep-Oct;23(5):729-39. doi: 10.1017/S0952523806230050.

Abstract

We report the results of psychophysical experiments with the so-called barber pole stimulus providing new insights on the neuronal processes underlying the analysis of moving features such as terminators or line-endings. In experiment 1, we show that the perceived direction of a barber pole stimulus, induced by line-ending motion, is highly dependent on the spatial frequency and contrast of the grating stimulus: perceived direction is shifted away from the barber pole illusion at high spatial frequency in a contrast dependent way, suggesting that line-ends are not processed at high spatial scales. In subsequent experiments, we use a contrast adaptation paradigm and a masking paradigm in an attempt to assess the spatial structure and location of the receptive fields that process line-endings. We show that the adapting stimulus that weakens most the barber pole illusion is localized within the barber pole stimulus and not at line-endings' locations. Current models of line-endings' motion processing are discussed in the light of these psychophysical results.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Ocular / physiology*
  • Functional Laterality / physiology*
  • Humans
  • Motion Perception / physiology*
  • Optical Illusions / physiology*
  • Photic Stimulation / methods
  • Reaction Time / physiology
  • Space Perception / physiology*
  • Time Factors