Optical blur and the perception of global coherent motion in random dot cinematograms

Jason J.S. Barton, Matthew Rizzo, Mark Nawrot, Trefford Simpson

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We evaluated the effect of +3.25 dioptres of optical blur on the discrimination of motion direction in random dot cinematograms. Dot displacement between frames varied from 2.1 to 63' of visual angle while the temporal interval was held constant. Optical blur worsened discrimination in three normal subjects at displacements below 16', but improved discrimination at displacements of 21' or more. In a second experiment, two subjects viewed equivalent velocity stimuli constructed with different combinations of temporal interval and spatial displacement. Results showed that the effect of blur was specific to displacement and not velocity. Furthermore, varying the dot density of the display showed that the effect of blur correlated with dot displacement and not the probability of dot mismatches. Since optical blur attenuates high spatial frequencies, this suggests that high spatial frequencies are important for motion perception when dot displacements are less than 16' to 21', but reduce motion perception at larger dot displacements. The use of random dot cinematograms in populations must take into account stimulus displacement and optical causes of reduced spatial acuity.

Original languageEnglish (US)
Pages (from-to)3051-3059
Number of pages9
JournalVision research
Issue number19
StatePublished - Oct 1996
Externally publishedYes


  • Blur
  • Directional discrimination
  • Motion
  • Random dot cinematogram

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

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