Speed tuning of direction repulsion describes an inverted U-function

William Curran, C.P. Benton

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Direction repulsion describes the phenomenon in which observers typically overestimate the direction difference between two superimposed motions moving in different directions (Marshak & Sekuler, Science 205(1979) 1399). Previous research has found that, when a relatively narrow range of distractor speeds is considered, direction repulsion of a target motion increases monotonically with increasing speed of the distractor motion. We sought to obtain a more complete measurement of this speed-tuning function by considering a wider range of distractor speeds than has previously been used. Our results show that, contrary to previous reports, direction repulsion as a function of distractor speed describes an inverted U-function. For a target of 2.5deg/s, we demonstrate that the attenuation of repulsion magnitude with high-speed disractors can be largely explained in terms of the reduced apparent contrast of the distractor. However, when we reduce target motion speed, this no longer holds. When considered from the perspective of Edwards et al.s (Edwards, Badcock, & Smith, Vision Research 38 (1998) 1573) two global-motion channels, our results suggest that direction repulsion is speed dependent when the distractor and target motions are processed by different globalmotion channels, but is not speed dependent when both motions are processed by the same, high-speed channel. The implications of these results for models of direction repulsion are discussed.
Original languageEnglish
Pages (from-to)1847-1853
Number of pages7
JournalVision Research
Issue number17
Publication statusPublished - Aug 2003

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Fingerprint Dive into the research topics of 'Speed tuning of direction repulsion describes an inverted U-function'. Together they form a unique fingerprint.

Cite this