SPATIAL LOCALIZATION IN STRABISMUS

The fundamental problem to which a strabismic must adapt centers about dealing with two disparate pieces of information regarding the location of an object from a visual system whose geometry, anatomy, and physiology indicate that it was designed to yield only one perceived location for each point in three-dimensional space. There is a paucity of systematic work aimed at the primary aspect of perception that relates to visual localization in the frontal plane. The present proposal is aimed at measuring binocular and monocular visual localization in the frontal plane. Monocular visual localization will be measured with each eye using auditory/visual matching of locations. The monocular judgments will be compared with localizations made by dichoptically matching two visual targets simultaneously. Previous work informs us that extraretinal eye position information (EEPI) will play a major role in controlling monocular egocentric and intersensory localization through the Cancellation Mechanism; but we have reason to believe that this will not be so in the dichoptic match, where it is anticipated that the mode of control of the mechanism generating visual localization will itself be different. Thus, intransitivities among the different measurements are anticipated. These intransitivities will throw light on anomalous retinal correspondence (ARC). Since we have already shown that flexibility in EEPI is involved in localization by the strabismic, the present work will build on that. Some of this work is aimed at uncovering the main basis for ARC. A model for control of visual localization that is derived from and closely tied to previous experiments on normal and curarized observers and strabismics will guide the research. The model extends the classical Cancellation Mechanism in new directions.