Stereopsis from contrast envelopes

K Langley, DJ Fleet, Paul Barry Hibbard

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

We report two experiments concerning the site of the principal nonlinearity in second-order stereopsis. The first exploits the asymmetry in perceiving transparency with second-order stimuli found by Langley et al. (1998) (Proceedings of the Royal Society of London B, 265, 1837-1845) i.e. the product of a positive-valued contrast envelope and a mean-zero carrier grating can be seen transparently only when the disparities are consistent with the envelope appearing in front of the carrier. We measured the energy at the envelope frequencies that must be added in order to negate this asymmetry. We report that this amplitude can be predicted from the envelope sidebands and not from the magnitude of compressive pre-cortical nonlinearities measured by other researchers. In the second experiment, contrast threshold elevations were measured for the discrimination of envelope disparities following adaptation to sinusoidal gratings. It is reported that perception of the envelope's depth was affected most when the adapting grating was similar (in orientation and frequency) to the carrier, rather than to the contrast envelope. These results suggest that the principal nonlinearity in second-order stereopsis is cortical, occurring after orientation- and frequency-selective linear filtering. (C) 1999 Elsevier Science Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)2313-2324
Number of pages12
JournalVision Research
Volume39
Publication statusPublished - Jul 1999

Keywords

  • second-order stereopsis
  • multiplicative transparency
  • depth asymmetry
  • HUMAN VISUAL SYSTEM
  • NON-FOURIER MOTION
  • BINOCULAR DISPARITY
  • SPATIAL-FREQUENCY
  • DEFINED CONTOURS
  • DEPTH
  • VISION
  • DISCRIMINATION
  • STEREOGRAMS
  • PERCEPTION

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