Asymmetry in Visual Search for Targets Defined by Differences in Movement Speed

Richard B. Ivry*, Asher Cohen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Perception of motion speed was investigated with the visual search paradigm, using human Ss. When searching for a fast target among slow distractors, reaction time was minimally affected as the number of distractors was increased. In contrast, reaction time to detect a slow target among fast distractors was slow and linearly related to the number of distractors. The effect cannot be attributed to differences in temporal frequency, discriminability, or one type of representation that might result from spatiotemporal filtering. An alternative hypothesis that can account for the asymmetry is that speed detectors operate as high-pass filters in the velocity domain. This hypothesis is in agreement with results obtained in psychophysical studies on motion adaptation as well as data from single-cell recordings in nonhuman species.

Original languageAmerican English
Pages (from-to)1045-1057
Number of pages13
JournalJournal of Experimental Psychology: Human Perception and Performance
Issue number4
StatePublished - Nov 1992
Externally publishedYes


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