Optokinetic nystagmus (OKN) pursuit phase velocity oscillations were studied in seven undergraduates during repeated 4 min presentation of optokinetic stimuli. The following variable parameters of the stimuli motion were used with each subject: horizontal direction, angular velocity (AV), and frequency-to-velocity ratio. AV of the OKN pursuit phases was found to decrease markedly within the first 30 sec of stimuli presentation with its successive increase and variously marked oscillations. Gradual decrease of the AV of OKN pursuit phases was observed at the end of the whole examination as compared to its beginning already within 4 min presentation of the moving stimuli. The results are discussed from the point of view of the arousal, and the activation components of visual attention.