Luminance and contrast cues are integrated in global shape detection with contours

Vision Res. 2008 Sep;48(21):2336-44. doi: 10.1016/j.visres.2008.07.015. Epub 2008 Aug 28.


Radial frequency (RF) contours can be used to represent the boundaries of natural objects, making them a useful stimulus with which to study shape processing. The current study used these contours to investigate whether luminance- and contrast-defined shape cues are combined in the detection of globally processed contours. A set of three experiments are presented. Experiment 1 shows that an RF contour defined by any one of positive or negative luminance contrast relative to background or second-order texture (contrast defined), is detected in accordance with a global pooling of local shape information. Experiment 2 uses a lateral masking paradigm to reveal interactions between global shapes defined by luminance of either polarity or a second-order contrast variation. Experiment 3 shows that an RF pattern defined by all three characteristics (positive, negative luminance polarity and contrast modulation) in nonoverlapping contour sections can still be assembled into a global shape. These findings indicate that at the level where RF contours are globally processed, luminance of either polarity- or contrast-defined shape information can be effectively combined.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Contrast Sensitivity / physiology
  • Cues*
  • Form Perception / physiology*
  • Humans
  • Lighting
  • Male
  • Pattern Recognition, Visual / physiology
  • Perceptual Masking / physiology
  • Photic Stimulation / methods
  • Psychophysics
  • Sensory Thresholds / physiology