Motion sickness and development of synergy within the spatial orientation system. A hypothetical unifying concept

Adaptation to research paradigms such as rotating rooms and optical alterat ion of visual feedback during movement results in development of perceptual -motor programs that provide the reflexive assistance that is necessary to skilled control of movement and balance. The discomfort and stomach awarene ss that occur during the adaptation process has been attributed to conflict ing sensory information about the state of motion. Vestibular signals depen d on the kinematics of head movements irrespective of the presence or absen ce of signals from other senses. We propose that sensory conflict when vest ibular signals are at least one component of the conflict are innately dist urbing and unpleasant. This innate reaction is part of a continuum that ope rates early in life to prevent development of inefficient perceptual-motor programs. This reaction operates irrespective of and in addition to reward and punishment from parental guidance or goal attainment to yield efficient control of whole body movement in the operating environment of the individ ual, The same mechanism is involved in adapting the spatial orientation sys tem to strange environments. This conceptual model "explains"' why motion s ickness is associated with adaptation to novel environments and is in gener al consistent with motion sickness literature. (C) 1999 Elsevier Science In c.