An oblique effect for transparent-motion detection caused by variation in global-motion direction-tuning bandwidths

Date

2007

Authors

Greenwood, John
Edwards, Mark

Journal Title

Journal ISSN

Volume Title

Publisher

Pergamon-Elsevier Ltd

Abstract

Despite evidence for the broad direction tuning of global-motion detectors, transparent motion can be detected with comparatively small angular separations. The exact means by which this broad population response is decoded to yield multiple signal directions remains unclear. Consequently, we sought to determine the relationship between angular separation thresholds for transparent motion and the direction-tuning bandwidth of global-motion detectors. Angular separation thresholds were assessed around four axes of motion, with thresholds lower around cardinal axes than the oblique axes. This was also found with lowered signal intensities, despite larger differences between the component directions at threshold, indicating that the transparency oblique effect relies more on the mean direction than the components. Simulations with a model global-motion population suggest this is likely to arise from variation in direction-tuning bandwidths around the cardinal and oblique axes. In a second experiment, adaptation to oblique unidirectional motion produced threshold elevation for a wider range of test directions than adaptation to a cardinal direction. This is consistent with tighter direction tuning around cardinal axes and provides a basis for the transparent-motion oblique effect. Our narrow bandwidth estimates also suggest that transparent-motion detection could rely on bimodal activity within the global-motion stage.

Description

Keywords

Keywords: article; controlled study; human; human experiment; movement perception; normal human; priority journal; Adaptation, Psychological; Anisotropy; Humans; Logistic Models; Motion Perception; Psychophysics; Sensory Thresholds; Visual Pathways Bandwidth; Global motion; Motion perception; Oblique effect; Transparency

Citation

Source

Vision Research

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1016/j.visres.2007.02.004

Restricted until

2037-12-31