Vibrotactile stimulators and virtual 3-D audio countermeasures, training and motion sickness symptoms with a simulated graveyard spin illusion.

The vestibular system by itself is incapable of effectively compensating for the graveyard spin illusion. We examined two countermeasures, i.e., efficacy of vibrotactile stimulation around the waist and virtual 3-D audio presented independently and jointly for controlling a simulated graveyard spin. We also examined: a) additional training with these countermeasures to improve "intuitiveness;" b) included non-perturbation trials along with perturbation trials; and c) monitored changes in well-being as measured by a motion sickness scale from pre- to post-test and immediately following each trial. Ten volunteers received two training and two test sessions. The somatogyral illusion was generated by accelerating a chair for 24 s until it attained a peak rotation of 120 degrees /s and then stopped. Over the ensuing 40 s the chair rotated in one of two random perturbation patterns or remained stationary. During this period, participants were required to eliminate all movements of the chair by turning a knob in the opposite direction of perceived rotation. For the control trials, participants relied solely on vestibular signals to cancel perceived movements. For the experimental trials, vibrotactile stimulation around the waist, virtual 3-D audio, or both were presented. The mean Cancellation Error (CE) for the control trials was 52 degrees /s. The application of the countermeasures significantly reduced the CE. Additional training and testing did not improve intuitiveness. Perturbations to the chair resulted in a higher CE than no perturbations. Motion sickness symptoms showed no differences from pre- to post-test and very rarely reported after each trial.

Sopite symptoms in the optokinetic drum.

UNLABELLED: Sopite syndrome is a disturbance caused by motion characterized by drowsiness and mood changes that may occur without the classic symptoms of motion sickness. Because sopite symptoms are often subtle, it is important to assess for their presence, and to distinguish true sopite symptoms from changes in mood and drowsiness that are due to non-motion related factors such as fatigue and boredom. We compared sopite symptoms in the optokinetic drum (OKD) with symptoms in a control condition in which the drum's motion cues were removed. METHODS: There were 48 Introductory Psychology students who were randomly assigned to 1 of 2 groups: the rotating stripes group (RS) sat inside a drum lined with black and white stripes. The drum rotated at 5 rpm. The control group (Ctrl) sat inside the same drum without stripes or rotation. All participants completed the Positive and Negative Affect Scale (PANAS), the Motion Sickness Assessment Questionnaire (MSAQ), and the Epworth Sleepiness Scale (ESS) at pre- and post-drum exposures. RESULTS: The RS, but not the Ctrl, showed increases on all four MSAQ subscales (gastric, peripheral, central, sopite). The groups showed equivalent decreases in positive and negative affect. These findings show that some sopite-related symptoms were due specifically to the motion stimuli, while others could be attributed to non-motion aspects of the experimental situation. DISCUSSION: The findings have implications for the use of control conditions in the study of sopite syndrome, and for methods of assessing the changes in mood and drowsiness that are the cardinal symptoms of sopite.