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Motion of contrast-modulated gratings is analysed by different mechanisms at low and at high contrasts

Lookup NU author(s): Professor Andrew Derrington

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Abstract

We used a pedestal test [Lu & Sperling (1995a). Vision Research, 35, 2697-2722] to determine whether motion discrimination of contrast-modulated gratings has different properties at low contrast (4.5%) and at high contrast (45%). The amplitude-modulated gratings consisted of a 5 c/deg static carrier modulated by a moving 1 c/deg contrast envelope. We found that when contrast is low direction discrimination for contrast-modulated gratings is vulnerable to pedestals and becomes impossible at about 4 Hz. At high contrast contrast-modulated gratings are unaffected by pedestals and modulation sensitivity in a motion direction-discrimination task remains high up to 12 Hz. These results are consistent with the hypothesis that separate mechanisms analyse motion of contrast-modulated gratings at low and at high contrast; at low contrast motion analysis is based on feature tracking, whereas at high contrast, contrast-modulated gratings are analysed by spatio-temporal filters.

Publication metadata

Author(s): Derrington AM; Ukkonen OI

Publication type: Article

Publication status: Published

Journal: Vision Research

Year: 2000

Volume: 40

Issue: 24

Pages: 3359-3371

ISSN (print): 0042-6989

ISSN (electronic): 1878-5646

Publisher: Pergamon

URL: http://dx.doi.org/10.1016/S0042-6989(00)00197-8

DOI: 10.1016/S0042-6989(00)00197-8

Notes: VISION RES

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