Location of Repository

Bias in perception of ambiguous movement in discrete stimulus presentations

By Paul Goddard, L. Blackaby and Steve Wilson

Abstract

Successive presentations of two different stimulus configurations were used to generate a compelling but ambiguous apparent-motion sequence, such that the likelihood of the perceived motion being resolved as clockwise or anticlockwise was equal. In the first stimulus configuration, four small squares were arranged in a square formation (5 deg × 5 deg) about a central fixation mark; in the second, they were arranged in a diamond formation. Twelve naïve observers reported perceived direction of motion in discrete presentations (< 1 s), comprising three stimulus configurations (square - diamond - square; stimulus configuration duration 100 ms; ISI 200 ms). We were surprised to find that ten of the observers exhibited a strong bias for motion in one or other direction. This bias to report a particular direction persisted even when observers were informed of the inherent ambiguity of the stimulus. Next, in extended presentations (2 min) five observers indicated each occurrence of a perceived switch in direction. Despite individual variation, all observers reported switches in direction; an analysis of the interswitch durations conformed to a gamma distribution. These observations support the notion that uninterrupted presentations are required for perceptual switching to occur in ambiguous displays (Leopold et al, 2002 Nature Neuroscience 5 605 - 609)

Topics: C800 Psychology, C850 Cognitive Psychology, C830 Experimental Psychology
Publisher: Pion
Year: 2003
OAI identifier: oai:eprints.lincoln.ac.uk:3616
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://eprints.lincoln.ac.uk/3... (external link)
  • http://www.perceptionweb.com/a... (external link)
  • http://eprints.lincoln.ac.uk/3... (external link)
  • Suggested articles


    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.