Abstract
Introduction: Most studies investigating visual development have assessed lower (local) and higher (global) levels of processing in isolation. It therefore remains unknown whether immature perception at one level affects processing in the other as a function of development. The objective of the present study was to assess the typical development of low- to mid-level visual processes by evaluating the discrimination of circular shapes (global) differing in local attributes: luminance and texture. Methods: Typically developing school-aged children (n = 11, 7-12 years olds), adolescents (n = 13, 13-17 years old) and adults (n = 13, 18-25 years old) were asked to discriminate a deformed circle (target) from a pure circle in a 2-ATFC using the method of constant stimuli; deformation thresholds were measured. Stimuli consisted of radial frequency patterns: circular contours with a varying number of bumps or deformations (radial frequencies (RFs) of 3, 5, and 10), which establishes the global shape. The amount of deformation is set by the amplitude or size of the bumps (dependent measure), and the patterns are defined by either luminance or texture (local information). Results: A 3-way mixed factorial analysis revealed a Group x Local Attribute interaction, demonstrating that for both luminance and texture patterns, the school-aged group performed significantly worse compared to adolescents and adults. No significant difference between adolescents and adults was identified. A Local Attribute x RF interaction was also demonstrated, with discrimination thresholds for luminance-defined patterns differing significantly across all RFs. Alternatively, for texture-defined patterns, discrimination thresholds did not differ for RFs of 5 and 10. Conclusions: These results suggest that the typical development of low- to mid-level visual processes is only influenced by the type of local attributes (luminance vs texture) and not by the number of RFs defining the contour. Overall, immature low-level visual processes can potentially affect higher-level perception.
Meeting abstract presented at VSS 2012