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Isabelle Legault, Remy Allard, Jocelyn Faubert; Curvature perception in aging. Journal of Vision 2006;6(6):197. doi: 10.1167/6.6.197.
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© ARVO (1962-2015); The Authors (2016-present)
It has been argued that curvature discrimination requires receptive fields sensitive to different orientations. Furthermore, aging monkeys are less efficient for orientation discrimination when compared to their younger counterparts. One purpose of the present study was to determine if curvature shape influences curvature perception. Another was to assess whether normal aging affects curvature perception given that curvature is believed to involve the integration of different oriented filters. Stimuli consisted of curvatures with three different shapes. The three shapes differed in that one was bell shaped, the second looked like a regular arc and the third appeared as a compressed arc. Ten young and ten older healthy observers participated in this study. Individual contrast thresholds were obtained to adjust for stimuli visibility. A 2AFC paradigm where the observers had to indicate in which interval the curvature was presented versus a straight line was used. The dependent variable observed was curvature amplitude. Results show that different amplitudes are necessary to detect curvatures of different shapes. Both aging and young observers obtained differences in sensitivity for the different shapes. The older observers showed higher thresholds for the arc and compressed arc shapes, while they were similar to the younger observers for the bell-shaped function. Those data suggest that alternate processes are required for different shapes. Possible explanations presently considered are that different orientation receptor pooling is necessary for the individual shapes or that they solicit different energy levels, both of which could be affected by normal aging.
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