Development of contour integration in macaque monkeys.

Studies of visual development show that basic metrics of visual development such as spatial resolution develop over the first 6-9 months in monkeys and over the first 6 or so years in humans. However, more complex visual functions may develop over different, or more protracted, time courses. To address the question of whether global perceptual processing is linked to or otherwise dependent on the development of basic spatial vision, we studied the development of contour integration, a global perceptual task, in comparison to that of grating acuity in macaque monkeys. We find that contour integration develops substantially later than acuity. Contour integration begins to develop at 5-6 months, near the time that acuity development is complete and continues to mature well into the second postnatal year. We discuss this later development in terms poor central efficiency and consider the relevant anatomy and physiology of the developing visual system. We conclude that contour integration is not likely to be limited by the same mechanisms that are permissive to acuity development, and may instead reflect the emergence of function central to V1.