Motion sickness during off-vertical axis rotation: prediction by a model of sensory interactions and correlation with other forms of motion sickness.

Motion sickness (MS) susceptibility of 108 normal subjects was measured during off-vertical axis rotation (OVAR) as a function of angular velocity (60-180 degrees/s). The chair rotated about a longitudinal axis tilted 30 degrees with respect to gravity. For each velocity, we measured the duration of exposure necessary to evoke a moderate malaise, with a limit of 30 min. MS appeared the fastest at a rotation velocity of 105 degrees/s; higher or lower velocities were less provocative. These results are in good agreement with predictions made by Zupan et al. [in ICANN'94, Springer-Verlag, 1995] by means of a MS mathematical model derived from a model of sensory interactions [Droulez and Darlot, in Attention and Performance, Vol. 13, Lawrence Erlbaum, Hillsdale, 1989]. We also found that MS susceptibility during OVAR is positively correlated with susceptibility to other forms of MS. Since OVAR induces sensory messages very different from those induced by other provocative stimulations, this could suggest that the sensitivity of a common final vegetative locus is an important factor of the individual differences in susceptibility to MS.