August 2010
Volume 10, Issue 7
Vision Sciences Society Annual Meeting Abstract  |   August 2010
Magnitude estimation of visual displays: numerosity, area, and mean size
Author Affiliations
  • Hunjae Lee
    Graduate Program in Cognitive Science, Yonsei University
  • Sang Chul Chong
    Graduate Program in Cognitive Science, Yonsei University
    Department of Psychology, Yonsei University
Journal of Vision August 2010, Vol.10, 1326. doi:
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      Hunjae Lee, Sang Chul Chong; Magnitude estimation of visual displays: numerosity, area, and mean size. Journal of Vision 2010;10(7):1326.

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

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Many studies have investigated the ability to compute statistical properties of a visual display, such as density (area), numerosity, and mean size. For example, Chong & Treisman (2005) investigated the ability to compute the mean size when number or density was varied. On the other hand, Burr (2008) focused on the ability to calculate numerosity under different densities. However, these researches did not investigate the ability to calculate those properties using same stimuli. In our study, we investigated the relationship among the abilities to judge area, numerosity and mean size by asking participants to make such judgments on same stimuli. A display with filled circles was presented and participants judged the three properties. The method of constant stimuli was used to measure PSEs (Point of Subjective Equalities) of each task on the same display. We used three different standards for each task and had 5 comparison stimuli at each standard. A standard display was presented for 250 ms followed by a test randomly selected from 5 comparison stimuli. Participants decided whether the test stimulus was larger or smaller (area and mean size tasks) or more or less numerous (a numerosity task) than the standard display. We found that PSEs of all three tasks were close to the presented standard, suggesting that all three judgments were accurate. However, participants overestimated all three properties at the highest standard. The amount of overestimation in the mean size judgments was significantly smaller than that in both area and numerosity judgments. These results suggest that the computation of mean size is closely related to that of area and number. It may be possible that the visual system calculates the perceived mean size by the ratio between perceived area and numerosity.

Lee, H. Chong, S. C. (2010). Magnitude estimation of visual displays: numerosity, area, and mean size [Abstract]. Journal of Vision, 10(7):1326, 1326a,, doi:10.1167/10.7.1326. [CrossRef]
 This research was supported by the Converging Research Center Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology (2009-0093901).

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