Can telepresent observers learn to take account of enhanced binocular disparities?

Binocular telepresence systems afford the opportunity of increasing the inter-camera distance (ICD) beyond the normal interocular distance (IOD) which magnifies the magnitude of the disparity information. This improves performance in nulling and matching tasks(1). Here we examine whether telepresent observers can learn to use enhanced disparities to accurately perform tasks requiring the recovery of Euclidean geometry (a shape task). The design comprised three phases: pre-adaptation (ICD = 6.5 cm), adaptation (ICD = 3.25 or 13 cm) and post- adaptation (ICD = 6.5 cm). Telepresent observers were required to adjust the magnitude of a depth interval (specified by binocular disparity) so that it matched a specified 2D interval specified by two lights (set between 5 and 15 cm) in an otherwise blacked-out scene. In the adaptation phase, the ICD/IOD ratio was changed to 0.5 or 2 and observers adjusted the depth interval repeatedly until a performance criterion was reached. Two forms of feedback were given in the adaptation phase: direct, where another light was shown at the correct disparity; and symbolic, where a signed number indicated the magnitude and direction of the error. Observers were clearly affected by ICD/IOD changes but learned the new ratio rapidly under both feedback conditions.