What is needed for a theory of mobility: direct perception and cognitive maps--lessons from the blind.

A theory of mobility using nonvisual stimuli and cognitive control process is proposed to augment Gibson's (1958, 1979) explanations of visual guidance. Nonvisual processes are clearly important to the totally blind, who often manage considerable independent mobility in the absence of vision, but are also important to the sighted. Mobility can be directed by visual control stimuli in the ambient optic array, by nonvisual control stimuli, as well as by processes of spatial learning, including stimulus-response (S-R) rote learning, motor plans, schemas, and cognitive maps. The selection of processes and strategies depends on the availability of particular information or on task demands. Attentional processes select stimuli for locomotor control within any particular modality and select between perceptual and cognitive processes. The skill of traveling through the spatial environment, avoiding obstacles, and traveling directly or indirectly toward goals, is a general characteristic of animal behavior and is described here by the term mobility. Although this term has a special connotation within blindness rehabilitation (Welsh & Blasch. 1980), it is used here to describe the overall processes of guidance by which both blind and sighted travelers move through space. The study of mobility encompasses several more traditional research concerns, such as space perception, motor control, and spatial cognition. Until recently there has been little research related to general psychological theory of mobility. A comparison may be made with the study of reading, where considerable research has taken place on component tasks such as letter extraction, word recognition, and eye movements, but where there has been comparatively little interest until recently in the general rules of the process (see Haber, 1978).