Vision & Action

As an animal moves relative to objects in the environment, changes in the patterning of reflected light from surfaces are potentially informative about such characteristics as surface composition, extent and slant, about the presence of obstacles or openings, the direction and velocity of relative movement, time to contact with surfaces and the severity of the impending contact. Similarly, attention is given to the visual guidance of interception: For example, we ask what optical patterns guide body and hand movements in catching. A major focus of our work is on the mathematics and physics of light at the ecological scale as a way to capture the information about such surface and locomotor transformations. Experiments involving dynamic computer displays allow the testing of the usefulness of candidate descriptions for guiding activity as well as the implications of such descriptions for understanding how optical information is detected by the visual perceptual system.

The optical patterns available to a moving or stationary perceiver-actor specify a variety of important properties of the environment, including the opportunities the environment offers for action. In the optical flow laboratory, we ask how significant aspects of the environment are specified by optical patterns and whether perceiver-actors exploit these patterns in perceiving and acting. Our concern has historically been with navigation: by what optical patterns do we guide our locomotion (steer, stop) through the environment. More recently we have sought to uncover principles of information-action coupling in interceptive tasks. Among the tasks we study are how outfielders run appropriately so as to catch fly balls, how one guides a reach to the side to intercept a ball with one hand, and how one times a volleyball smash.