Mechanisms specialized for the perception of image geometry

Angle discrimination thresholds were obtained for V-shaped targets with a base angle of 90 deg at four different pattern orientations (0, 45, 90 and 135 deg). A comparison of these thresholds with the orientation discrimination thresholds for the single lines from which the patterns had been constru...

Full description

Saved in:
Bibliographic Details
Published in:Vision research (Oxford) 1996-11, Vol.36 (22), p.3607-3627
Main Authors: HEELEY, D. W, BUCHANAN-SMITH, H. M
Format: Article
Language:English
Subjects:
Biological and medical sciences
Discrimination (Psychology)
Fundamental and applied biological sciences. Psychology
Humans
Models, Psychological
Perception
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Psychophysics
Sensory Thresholds
Space Perception
Vision
Visual Acuity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Angle discrimination thresholds were obtained for V-shaped targets with a base angle of 90 deg at four different pattern orientations (0, 45, 90 and 135 deg). A comparison of these thresholds with the orientation discrimination thresholds for the single lines from which the patterns had been constructed, revealed that angle acuity cannot be predicted from component acuity. Angle acuity is finer than the corresponding orientation acuity in all cases and does not exhibit the pronounced oblique effect that is found for orientation discrimination. Other experiments showed that acuity for pattern angle depends critically on base angle, with minima close to 0, 90 and 180 deg. The shape and amplitude of this function are independent of pattern orientation. It was found that the angle acuity was unaffected by excluding a large portion of the target in the region of the vertex, and that the pattern of dependence of acuity on angle changed radically when the target was reduced ultimately to three blobs that defined the cardinal points of the stimulus. The data suggest that when the target comprises line segments, angle discrimination is not limited by noise that arises at early levels of processing and that angle perception is mediated by mechanisms that are specialized for the perception of image geometry. An opponent process model, that is based on the combined outputs of just two types of filter, is proposed as the basis for the perception of image geometry. This type of system is appropriate for computing one of the differential invariants in an optic flow field.
ISSN:0042-6989
1878-5646
DOI:10.1016/0042-6989(96)00077-6