Motion-induced overestimation of the number of items in a display

Seyed Reza Afraz, Roozbeh Kiani, Maryam Vaziri-Pashkam, Hossein Esteky

Research output: Contribution to journalArticlepeer-review


Subjects were asked to report the number of items in a display as the items moved along a circular path around the fixation point. As the rotation speed increased, the apparent number of items also increased. This motion-induced overestimation (MIO) effect was investigated in three experiments. In the first experiment, the effect of rotation speed and set size was explored with an enumeration task. The overestimation error increased with an increase in speed or number of items in the display. In the second experiment, we used an adjustment paradigm to measure the speed threshold of MIO effect onset. Temporal rate of the display, which was defined as product of rotation speed and the number of rotating items, was the determining factor of MIO onset. In the third experiment, moving items were marked with different colours. Surprisingly, the number of perceived items was still overestimated even though the number of perceived colours was not.

Original languageEnglish (US)
Pages (from-to)915-925
Number of pages11
Issue number8
StatePublished - 2004

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Ophthalmology
  • Sensory Systems
  • Artificial Intelligence


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