Do observers exploit binocular disparity information in motor tasks within telepresence environments ?

Increasingly, binocular disparity has become commonplace in telepresence systems despite the additional cost of its provision. Experiments comparing performance under monocular and binocular viewing are often cited as justification for its use. Here we question whether this experimental comparison and provide an important set of data which compares performance on a motor task under binocular, monocular and bi-ocular (where both eyes receive the same view) conditions. Binocular cues were found to be particularly important in the control of the transport component. In the binocular conditions peak velocity scaling with object distance was greater than in the other conditions, and in the bi-ocular condition, where the binocular distance cues conflicted with pictorial information, no scaling was evident. For the grasp component, even in the presence of conflicting size and depth information, grip scaling remained equivalent in all conditions. For the transport component at least, binocular cues appear important and the decrease in performance observed in behavioural studies under monocular conditions is not attributable to lack of information in one eye but rather to the lack of binocular depth cues. Therefore in the design of telepresence systems to be used in telemanipulation tasks, the use of stereoscopic display technology seems justified.