Space flight represents a form of sensory stimulus rearrangement requi
ring modification of established terrestrial response patterns through
central reinterpretation. Evidence of sensory reinterpretation is man
ifested as postflight modifications of eye/head coordination, locomoto
r patterns, postural control strategies, and illusory perceptions of s
elf or surround motion in conjunction with head movements. Under norma
l preflight conditions, the head is stabilized during locomotion, but
immediately postflight reduced head stability, coupled with inappropri
ate eye/head coordination, results in modifications of gait. Postfligh
t postural control exhibits increased dependence on vision which compe
nsates for inappropriate interpretation of otolith and proprioceptive
inputs. Eye movements compensatory for perceived self motion, rather t
han actual head movements have been observed postflight. Overall, the
in-flight adaptive modification of head stabilization strategies, chan
ges in head/eye coordination, illusionary motion, and postural control
are maladaptive for a return to the terrestrial environment.