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Human speed perception is contrast dependentWhen two parallel gratings moving at the same speed are presented simultaneously, the lower-contrast grating appears slower. This misperception is evident across a wide range of contrasts (2.5-50 percent) and does not appear to saturate (e.g. a 50 percent contrast grating appears slower than a 70 percent contrast grating moving at the same speed). On average, a 70 percent contrast grating must be slowed by 35 percent to match a 10 percent contrast grating moving at 2 deg/sec (N = 6). Furthermore, the effect is largely independent of the absolute contrast level and is a quasi-linear function of log contrast ratio. A preliminary parametric study shows that, although spatial frequency has little effect, relative orientation is important. Finally, the misperception of relative speed appears lessened when the stimuli to be matched are presented sequentially.
Document ID
19930042953
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Stone, Leland S.
(NASA Ames Research Center Moffett Field, CA, United States)
Thompson, Peter
(York Univ. United Kingdom)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: Vision Research
Volume: 32
Issue: 8
ISSN: 0042-6989
Subject Category
Behavioral Sciences
Accession Number
93A26950
Funding Number(s)
PROJECT: RTOP 199-16-12-37
PROJECT: RTOP 506-71-51
Distribution Limits
Public
Copyright
Other

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