September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
When and why does adaptation increase perceived number?
Author Affiliations
  • Emilie Shepherd
    Department of Psychology, Swarthmore College
  • Frank Durgin
    Department of Psychology, Swarthmore College
Journal of Vision August 2017, Vol.17, 1256. doi:10.1167/17.10.1256
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      Emilie Shepherd, Frank Durgin; When and why does adaptation increase perceived number?. Journal of Vision 2017;17(10):1256. doi: 10.1167/17.10.1256.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Burr and Ross (2008) reported that adapting to low numbers of elements (like 12 dots) increased the perceived number of field of more dots presented to the same location. On average their data from 2 observers showed that about 42% more dots were required in an unadapted region to seem equivalent. We sought to replicate and extend their observation. In a first study, we tested effects of adaptation to patterns of 12 dots using the 7-second re-adaptation to a stationary pattern employed by Burr and Ross between test trials. The average effect size was about 30% (95% CI: 12%, 41%) for seven naïve subjects tested with gaze monitoring via eye-tracker. In a second study we sought to measure possible effects of attention by presenting the comparison field sequentially rather than simultaneously for half of our 17 new observers. We additionally tried to strengthen adaptation by showing 7 different adapting fields of 12 dots each (600 ms on; 400 ms off) rather than just one for 7 seconds. The effect size for sequential comparisons did not differ from that for simultaneous comparison, but the overall magnitude of adaptation was sharply reduced to about 15% for both (95% CI: 6%, 25%). At least three possibilities exist for the reduction in magnitude of the effect. First, the total adaptation time was only 60% of 7 s, and thus, the amount of adaptation might be simply time dependent. Second, the seven different adapting dot patterns might be virtually merged so that the adaptation region was more uniformly adapted compared to a single sparse adaptation stimulus viewed for 7 seconds. Finally, it remains possible that increased number perception is produced by superimposed afterimages of displays with low spatial frequencies – a process partly ameliorated by the variable flashing adaption displays.

Meeting abstract presented at VSS 2017

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