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Development of Sensitivity to Texture and Contour Information in the Human Infant

¹ The Smith-Kettlewell Eye Research Institute, ² Stella Maris Institute, Pisa, ³ Weizmann Institute of Science, Rehovot, Israel

Reprint request should be sent to Anthony M. Norcia, The Smith-Kettlewell Eye Research Institute, 2318 Fillmore Street, San Francisco, CA 94115, or via e-mail: amn{at}ski.org.

Texture discrimination and bounding contour extraction are essential parts of the object segmentation and shape discrimination process. As such, successful texture and contour processing are key components underlying the development of the perception of both objects and surfaces. By recording visual-evoked potentials, we investigate whether young infants can detect orientation-defined textures and contours. We measured responses to an organized texture comprised of many Gabor patches of the same orientation, alternated with images containing the same number of patches, but all of random orientation. These responses were compared with a control condition consisting of the alternation between two independently random configurations. Significant difference potentials were found as early as 2–5 months, as were significant odd harmonics in the test conditions. Responses were also measured to Gabor patches organized either as circles (all patches tangent to an imaginary circular path) alternated with pinwheels (all patches having a fixed orientation offset from the path). Infants between 6 and 13 months also showed sensitivity to the global organization of the elements along contours. Differential responses to our texture and contour stimuli and their controls could only have been generated by mechanisms that are capable of comparing the relative orientation of 2 or more patches, as no local information at a single patch distinguished the random and organized textures or the circle and pinwheel configurations.

Key Words: Development • electrophysiology • event-related potentials • occipital cortex • perception: low-level vision

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