1. A method of detecting and characterizing square wave jerks in the eye movements of a person, for the differential diagnosis of oculomotor and neurological disease comprising: a) obtaining a sequence of saccades; b) identifying pairs of consecutive saccades of the sequence; c) determining whether each saccade of each identified pair is opposite the direction of the other saccade and, if not, then discarding the pair; d) determining whether a magnitude of each saccade of each identified pair is comparable and, if not, then discarding the pair; e) determining whether the pair of saccades of each identified pair are temporally related by a predetermined time period and, if not, then discarding the pair; and f) collecting any remaining pairs of saccades as square wave jerks.