September 2018
Volume 18, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2018
Size and Aspect Ratio Judgments in Younger and Older Adults
Author Affiliations
  • Jessica Cali
    Department of Psychology Neuroscience & Behaviour, McMaster University
  • Patrick Bennett
    Department of Psychology Neuroscience & Behaviour, McMaster University
  • Allison Sekuler
    Department of Psychology Neuroscience & Behaviour, McMaster UniversityRotman Research Institute, Baycrest Health Sciences
Journal of Vision September 2018, Vol.18, 1313. doi:
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      Jessica Cali, Patrick Bennett, Allison Sekuler; Size and Aspect Ratio Judgments in Younger and Older Adults. Journal of Vision 2018;18(10):1313.

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

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Size and aspect ratio are attributes of two-dimensional shapes that are hypothesized to be encoded by mid-level visual areas, and are thought to be important for shape and object perception. Shape and object perception is affected by aging, but it is unclear if these age-related changes are due to changes in sensitivity to size or aspect ratio. To address this issue, we measured sensitivity to changes in aspect ratio and relative size in two groups of older adults (M = 67 and 72 years) and younger adults (M = 21 and 20 years). In the aspect ratio task, observers viewed a centrally positioned moving rectangular and reported whether the figure was longer vertically or horizontally. In the size task, observers viewed a moving reference rectangle for 300 ms followed by a moving test rectangle, and reported whether the second figure was larger or smaller than the reference. Stimulus duration was varied between 15 and 210 ms. Psychometric functions were fit to the data to estimate 70% discrimination thresholds. Observers completed the tasks in three conditions: 1) complete, with the entire outline of the rectangle visible; 2) fragmented, with corners of the rectangle deleted; and 3) occluded, resembling the fragmented condition, except with corners occluded by opaque squares. In conditions 2 and 3, perceptual completion of the rectangle was expected to aid judgment of size or aspect ratio. In both tasks, thresholds were higher in older adults, suggesting that older adults may experience a general deficit in shape perception. Thresholds in both age groups decreased as a function of stimulus duration, and were lower in the size discrimination task than in the aspect ratio task. We are currently exploring how differences in the three stimulus types may be related to how performance changes with stimulus duration

Meeting abstract presented at VSS 2018


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