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John Hayes; Spatio-temporal characteristics of a rotating segmented ring.. Journal of Vision 2012;12(9):321. doi: 10.1167/12.9.321.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to identify the optimal characteristics of a rotating segmented ring in a single subject design. The black and white segmented target optotype on a gray background had a 20.25mm diameter with 9 levels of thickness (4–20% of diameter), 3 levels of segmentation (4,6,8) and 10 levels of rotation (10-100RPM). Primary outcome was the distance to detect the target. Target was presented on a 17" monitor with 75hz refresh rate between two other rotating optotypes with the same characteristics, but 5% larger and smaller. The subject moved forward until he could see the target and the larger optotype, but not the smaller. Distance was correlated with number of segments (r=.87), thickness (.345), segment area (.758), and RPM (-.248). In a stepwise linear regression (R2=.94) distance = 6.8(feet) + 2.3*segment length + 2.8*thickness - .14*RPM (all p<.001). Analysis of residuals yielded a quadratic effect of RPM (R=.13, p=.25, optimal 35RPM), quadratic effect of # segments (R=.12, p=.29, optimal 6-7 segments), cubic effect of thickness (R=.50, p<.001, optimal 10% of diameter). Only the effect of thickness demonstrated a statistically significant deviation from a linear relation between the optotype characteristics and threshold distance. The number of segments and RPM graphically supported an optimal relationship that should be tested with more levels and subjects. In conclusion, the ability to detect a rotating, segmented ring is not a simple acuity task based on a linear function of the size of the segments.
Meeting abstract presented at VSS 2012
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