Visual control of grasping with abnormal binocular vision

Intuitively, perception of depth would seem important for the ability to interact with objects in the environment. Without proper depth perception, it is difficult to imagine picking up objects with the hands, and navigating around obstacles while walking. Although it is well established in vision science that normal depth perception depends on having two functional eyes (i.e., binocular vision), there is actually very little evidence available on the question of whether a person's ability to interact physically with their environment is disrupted when binocular vision is impaired. In fact, up to 5% of the adult population may demonstrate some aspect of abnormal binocular vision, due to conditions like the loss of one eye (i.e., enucleation), or amblyopia (a developmental visual problem in which the two functional eyes don't work together). There is good reason to believe that the brain can learn to compensate for abnormal binocular vision by using different sources of visual information, so that relatively normal body movements remain possible. The purpose of the present research is to study a common movement pattern - reaching and grasping an object - in individuals who do not have normal binocular depth perception, to determine if any deficits can be detected. By studying performance in conditions that provide augmented sources of visual information, our goal is to determine if these individuals can learn to overcome their visual deficit to perform grasping movements in a relatively normal manner. This research will help us to understand the functional consequences of abnormal depth perception, and to develop better training/rehabilitation programs for those affected individuals.