DISPARITY-EVOKED VERGENCE IS DRIVEN BY INTEROCULAR CORRELATION

Disparity-evoked vergence is studied in stereograms showing one or two depth planes which are defined by isolated dots of varying density an d contrast. Vergence position immediately after stimulus presentation was measured using dichoptic nonius lines. Since the stimulus was not visible after the onset of the vergence movement, the experiment acces ses the initiation of vergence rather than its eventual result. In the unequivocal stimuli (one depth plane), elicited vergence tends to red uce disparity. Disparities of 0.5-1 deg are most effective which is in accordance with earlier findings. If two depth planes are presented, elicited vergence lies between the two planes, approaching the plane w ith higher dot density and/or dot contrast. In quantitative measuremen ts, we show that the depth-averaging mechanism uses signal power per d epth plane as a weight. Therefore, the relative pulling strength of do t density compared with dot contrast follows a power law with exponent 2. We propose a population code for vergence control based on dispari ty-tuned pools of units. Copyright (C) 1996 Elsevier Science Ltd.