Adaptation to optokinetic rotation-induced motion sickness without experiencing nausea.

17 subjects highly susceptible to motion sickness were divided into Nausea and No-nausea groups depending upon whether the subjects experienced nausea during adaptation to nauseagenic rotation. Eight subjects in the Nausea group viewed an optokinetic rotation drum for repeated sessions of 16 min., with an interval of two days between every two sessions. During each session the subjects continuously viewed the rotating drum 16 min. even if they experienced nausea. nine subjects in the No-nausea group likewise viewed an optokinetic rotation drum for at most 16 min. but immediately stopped viewing the rotating drum whenever they experienced nausea during the session. The criteria for full adaptation were that the subject reported no feelings of stomach discomfort and nausea during a 16-min session. The mean number of sessions to reach full adaptation was 3.9 (SD = 0.6) with a range 3 to 5 sessions for the subjects in the Nausea group and 3.2 (SD = 0.8) with a range 2 to 4 for the subjects in the No-nausea group. It was concluded that subjects can adapt to a nauseagenic optokinetic rotation by repeated exposure without experiencing nausea and vomiting during adaptation.