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Vision Res. 2006 Mar;46(6-7):782-6. Epub 2005 Sep 19.

Speed can go up as well as down at low contrast: implications for models of motion perception.

Author information

1
Department of Psychology, University of York, York YO10 5DD, UK. pt2@york.ac.uk

Abstract

It is well-known that reducing the contrast of a slow moving stimulus reduces its apparent speed. [Thompson, P. (1982). Perceived rate of movement depends on contrast. Vision Research, 22, 377-380.] report of this finding also suggested that at speeds above 8 cycles/s reducing contrast increased perceived speed. However in a later report, Stone and Thompson (1992), using a more rigorous, forced-choice procedure, failed to collect reliable data at these higher speeds. Here, we confirm that faster moving stimuli can appear to move faster than their true speed at low contrasts and we propose a physiologically plausible ratio model that unlike recent Bayesian models (e.g. Weiss, Y., Simoncelli, E. P., & Adelson, E. H. (2002). Motion illusions as optimal percepts. Nature Neuroscience, 5, 598-604) can account well for the results.

PMID:
16171842
DOI:
10.1016/j.visres.2005.08.005
[Indexed for MEDLINE]
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