Can observers exploit enhanced-disparity information to control reaching movements within telepresence environments?

The control of inter-camera distance (ICD) can be used to change the range of binocular disparities available from a visual scene viewed remotely. Binocular disparity is considered pre-eminent in the control of reaching behaviour. One reason for this is that once suitably scaled (with an estimate of viewing distance and inter-ocular distance) it can specify metrical depth relationships within a scene. Such information is necessary in order to plan the transport and grasp phase of a reaching movement (i.e. absolute distance and size are required). However whether an observer can take advantage of enhanced disparities to control reaching is unknown. Here we examine the effects of manipulating ICD on reaching movements with ICDs ranging from 6.5cm to 26cm. Typically sized, real world objects (both familiar and unfamiliar) were placed in a scene and reaching performance was assessed. An experimental sequence consisted of three blocks. The first and last block used a normal ICD/IOD of 6.5 cm whereas the middle block used an increased ICD. Larger than normal ICD were found to disrupt reaching performance, with slower peak velocities and smaller grip apertures being observed. This was more pronounced for unfamiliar objects. Little evidence for learning was found.