Independence of conjugate and disjunctive eye movements

Conjugate eye movements, in which the two eyes move in a parallel fashion, can be distinguished from disjunctive eye movements, in which the fixation axes of the two eyes move with respect to each other. Recent experiments (Westheimer & Mlitchell, 1956; Yarbus, 1957) have demonstrated clearly that the two types of movements can occur simultaneously and seem to be additive. The purpose of this paper is to illustrate by some further experimental results that conjugate and disjunctive eye movements are organized independently.