Some temporal aspects of stereoacuity

Stereoacuity thresholds improve considerably with practice when measured using three vertical lines 15' apart horizontally and presented briefly. For experienced observers, these thresholds are relatively independent of exposure time for stimulus durations smaller than 100 msec. The thresholds are 2-3 times larger when the outer flanking lines are shown continuously than when they and the central target line are turned on and off simultaneously. When the target and flanking lines are shown sequentially, stereoacuity thresholds can be predicted from the number of times the configuration is presented. Changes in thresholds can be measured for intervals as small as 5 msec between successive presentation of the relative disparity configuration. The underlying mechanism is modeled well by a first order auto-regression process.