Visual sensitivity to disparity pulses: evidence for directional selectivity.

Abstract When a target's retinal disparity changes with a pulsed waveform, the target appears to execute a pulsed movement in depth. Visual sensitivity to such disparity changes was plotted as a function of pulse duration. These curves resembled low-pass filter characteristics. For a given direction of movement in depth, different sensitivity curves were obtained for targets located in front of and behind the plane of binocular fixation. However, depth sensitivities were similar for pulses directed from either locationtowards the fixation plane or directed from either locationaway from the plane. This suggests that movements in depth directed towards and away from the fixation plane are handled by different neural mechanisms in man in accord with single-neuron evidence in cat and monkey.