Differential vertical visual latency as determined with a simultaneity paradigm.

Behavioral studies, as well as anatomical and physiological data, suggest differences in functionality for inferior and superior visual fields. Previous investigations comparing latencies of the two fields have employed motor reaction times. This approach is of limited usefulness in elderly clinical populations where various degrees of motor impairment may be present. In this report, we describe a simultaneity paradigm that allows the determination of relative latencies without dependence on motor reaction times. A slightly, but statistically significant, shorter latency (3.9+/-5.9ms) was found for the superior visual field. The results are not affected by age, and both within- and between-session variability are low.