Organisation of signals involved in binocular perception and vergence control

A novel type of dynamic random-dot stereogram (DRS) was used to study vergence movements and depth detection in response to temporal modulations of interocular correlation. Each DRS consisted of the repeated presentation of a pair of correlated images alternated by the presentation of a pair of uncorrelated images. The intervals of high (T(c)) and low (T(u)) correlation varied from 14 to 224 ms in steps of 14 ms. Depth detection and vergence responses behaved very different from each other as functions of T(c) and T(u). The different behaviours suggest that depth and vergence most likely result from independent streams of disparity processing. It is speculated that magnocellular layers process disparities that drive vergence and that a parvocellular stream of disparity processing is involved in depth perception. This suggestion is discussed in relation to recent findings on binocularly perceived direction and depth. The discussion leads to suggesting a headcentric organisation of signals involved in binocular perception and a retinal organisation of signals involved in vergence control.