2nd-order processes in the human perception of motion and texture

1992 1992

Other formats: Order a copy

Abstract (summary)

2nd-order lateral inhibition. When a central texture patch C, is surrounded by a texture field S, the perceived contrast of C depends substantially on the contrast of the surround S (with mean luminance held constant). When C is surrounded by a high-contrast texture with similar spatial frequency content, it appears to have less contrast than when it is surrounded by a uniform background. The induced reduction of apparent contrast is greatly diminished when (i) C and S are filtered into non-overlapping spatial frequency bands, or when (ii) C and S are presented to different eyes. When C and S are special textures designed to selectively stimulate either the on-center or off-center visual system, the reduction of C's apparent contrast does not vary with the combination of on-center and off-center textures. When C and S gratings are perpendicular, S causes less of a reduction in C's apparent contrast than it does when they are parallel. This orientation specificity increases with increasing spatial frequency and decreasing stimulus contrast. These results indicate a 2nd-order lateral inhibition with a neural locus central to that of on-center/off-center interaction and mediated by an early cortical or precortical cell population.

Mechanisms of 2nd-order motion perception. Two kinds of stimuli that are invisible to 1st-order (Fourier) motion mechanisms are tested: (1) stimuli for which motion information is lost following full-wave rectification ("half-wave stimuli") and (2) stimuli for which motion information is lost following half-wave rectification ("full-wave stimuli"); given sufficient contrast, both convey motion. All observers perceive full-wave motion; only one-third perceive half-wave motion. Remarkably, full-wave stimuli are perceived slightly more efficiently than Fourier stimuli, and much more efficiently than half-wave stimuli. When either full-wave and Fourier or half-wave and Fourier gratings are presented simultaneously, there is a wide range of relative contrasts within which the directions of both gratings are easily determinable. Conversely, when half-wave and full-wave gratings are combined, the direction of only one of these gratings can be determined with high accuracy. Conclusion. Fourier ("1st-order") and non-Fourier ("2nd-order") motion systems are fully separate; full-wave and half-wave mechanisms share resources.

Indexing (details)

0623: Psychology
0623: Experiments
Identifier / keyword
Psychology; motion perception; texture perception; visual processing
2nd-order processes in the human perception of motion and texture
Solomon, Joshua Adam
Number of pages
Publication year
Degree date
School code
DAI-B 53/11, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Sperling, George
New York University
University location
United States -- New York
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.