Ukkonen, O.I. and Derrington, A.M. (2000) Motion of contrast-modulated gratings is analysed by different mechanisms at low and at high contrasts. Vision Research, 40 (24). pp. 3359-3371. ISSN 0042-6989 .
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| Official URL http://dx.doi.org/10.1016/S0042-6989(00)00197-8 |
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.
| Item Type: | Article |
|---|---|
| Additional information: | VISION RES |
| Subjects: | B Philosophy. Psychology. Religion > BF Psychology |
| Divisions: | Faculties > Social Sciences > School of Psychology |
| Depositing User: | C.A. Simms |
| Date Deposited: | 26 May 2009 19:33 |
| Last Modified: | 14 Jan 2010 14:15 |
| Resource URI: | http://kar.kent.ac.uk/id/eprint/4508 (The current URI for this page, for reference purposes) |
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