ABSTRACT Global summation of radial frequency patterns and the effect of sudden onset glare on shape discrimination The purpose of this study was to provide evidence of global pooling around the circumference of the Radial frequency (RF) pattern, and to study the effect of sudden onset glare on shape discrimination. The RF stimuli were generated by the amplitude modulation of the radius of a circle which deforms them from circularity, while the cross sectional luminance profile was the fourth derivative of Gaussians (D4). The amplitude of the stimuli determines how distinct the pattern is and thus measures the degree of sensitivity while the radial frequency determines the number of lobes the pattern has. In the first part of the study, whole RF patterns (RF3 to RF16) and open component fractions (0.125, 0.25, 0.5, 0.75), which are incomplete sectors of the whole, were tested against their respective reference unmodulated patterns. Subjects were tasked with discriminating minute deviations from their reference patterns. In the second part of the study, high contrast (20 X detection threshold) RF3 and RF4 contours and equivalent low contrast (5 X detection threshold) RF3 and RF4 contours were used as stimuli. Shape discrimination threshold for the high contrast target was determined with and without sudden onset glare. The result of the first part of the study showed that threshold decreased significantly as larger component RF patterns were tested (p
| Date of Award | Jun 12 2014 |
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| Original language | English |
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| Supervisor | Bin Zhang (Supervisor) |
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