While there have been at least 100 papers reporting cases of voluntary nystagmus since 1900, there have been very few quantitative determinations of its characteristics.7,14 Little is actually known concerning the etiology of this phenomenon, although theories ranging from ocular pathology12 to alternating innervation of opposite-pair members of the lateral rectus muscles have been proposed.1,4,11 The case studies, which comprise the majority of the reference material, can be summarized quite simply. An individual often not possessing a past history of pathology is discovered to have the ability to "jiggle" his eyeballs at will, in a predominantly horizontal direction, for periods ranging from 6-8/sec6 to about 35/sec.13 The frequency of this "jiggling" has been reported to be within a range of from 7-8/sec2 to 23/sec.7 There are only a few investigations in which photographic or corneoretinal potential records were obtained of voluntary nystagmus.