The influence of target width on optokinetic nystagmus.

The influence of the width of the targets on optokinetic nystagmus (OKN) was investigated over a range of 1/2 degree to 5 degrees, corresponding to a proportion between light and dark from 1:10 to 1:1. The width of the targets and the target speed showed a reciprocally modifying effect on the regularity of the optokinetic response. With a target speed of 20 degrees/sec the influence of the width of the targets was counterbalanced by the effect of the target speed. The width of the targets did not modify the eye velocity of the slow phase. The frequency of the OKN was positively correlated to the width of the targets.