T Banton1, B I Bertenthal. 1. Department of Psychology, University of Virginia, Charlottesville, USA.
Abstract
PURPOSE: Image flow across the retina can be classified into several types of motion specifying information about spatial layout and self-movement. Adults process these types of motion via different functional pathways. This article investigates the development of these functional pathways. METHODS: The development of sensitivity to several classes of motion is reviewed and correlated with the neural development of the visual system. RESULTS: Different types of motion processing develop at different rates. The clearest example is that sensitivity to direction of translation shows an earlier onset and a different developmental trajectory than sensitivity to shearing motion. In addition, the onset of sensitivity to translation direction and shearing motion coincides with the development of striate laminae 5/6 and 4B, respectively. This earlier development of the deeper striate laminae is also consistent with reports of neonatal direction discrimination in displays undergoing optical expansion and rotation. CONCLUSIONS: Sensitivity to at least two types of motion, translation and shearing, develop in different ways and continue to be processed differently in adulthood. The differential development of sensitivity to these motion types coincides with the laminar development of striate cortex. It thus follows that the nonuniform development of the motion-processing system must be recognized to assess infant motion sensitivity correctly.
PURPOSE: Image flow across the retina can be classified into several types of motion specifying information about spatial layout and self-movement. Adults process these types of motion via different functional pathways. This article investigates the development of these functional pathways. METHODS: The development of sensitivity to several classes of motion is reviewed and correlated with the neural development of the visual system. RESULTS: Different types of motion processing develop at different rates. The clearest example is that sensitivity to direction of translation shows an earlier onset and a different developmental trajectory than sensitivity to shearing motion. In addition, the onset of sensitivity to translation direction and shearing motion coincides with the development of striate laminae 5/6 and 4B, respectively. This earlier development of the deeper striate laminae is also consistent with reports of neonatal direction discrimination in displays undergoing optical expansion and rotation. CONCLUSIONS: Sensitivity to at least two types of motion, translation and shearing, develop in different ways and continue to be processed differently in adulthood. The differential development of sensitivity to these motion types coincides with the laminar development of striate cortex. It thus follows that the nonuniform development of the motion-processing system must be recognized to assess infant motion sensitivity correctly.