Related Experiment Video
Updated: Jul 4, 2026

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Vision for perception and vision for action: normal and unusual development
Daniel D Dilks1, James E Hoffman, Barbara Landau
1Department of Cognitive Science, Johns Hopkins University, USA. dilks@mit.edu
Abstract:
Evidence suggests that visual processing is divided into the dorsal ('how') and ventral ('what') streams. We examined the normal development of these streams and their breakdown under neurological deficit by comparing performance of normally developing children and Williams syndrome individuals on two tasks: a visually guided action ('how') task, in which participants posted a card into an oriented slot, and a perception ('what') task, in which they matched a card to the slot's orientation. Results showed that all groups performed worse on the action task than the perception task, but the disparity was more pronounced in WS individuals and in normal 3-4-year-olds than in older children. These findings suggest that the 'how' system may be relatively slow to develop and more vulnerable to breakdown than the 'what' system.
Related Concept Videos
Vision
Depth Perception and Spatial Vision
Gestalt Principles of Perception
Visual System
Once through the pupil, the light passes through the lens, a...
Photoreceptors and Visual Pathways
Parallel Processing

