Before clinical exploitation of optic nystagmus can be safely attempted, the most complete possible understanding of the normal physiology of this phenomenon must be gained. Early in our work in studying the records of normal subjects the influence of certain psychologic conditions on the nystagmographic pattern was appreciated. In a series of moving visual stimuli of varying complexity, those of little interest commonly evoked only a momentary glance while those of special interest were pursued longer, sometimes to the physiologic limit. Here was an indication that the amplitude of the slow phase might be modified by the psychologic factor called interest. In like manner the amplitude of the quick phase seemed to be influenced by the factor of relative interest engendered by different oncoming objects competing for renewed fixation. In addition, the more complex the object of regard, the greater the number of short quick phases or refixations occurring within