Douglas G. Watt

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Experiments on human spatial orientation were conducted on four crewmembers of Space Shuttle Spacelab Mission 1. This introductory paper presents the conceptual background of the project, the relationship among the experiments and their relevance to a “sensory reinterpretation hypothesis”. Detailed experiment procedures and results are presented in the(More)
Reflex responses that depend on human otolith organ sensitivity were measured before, during and after a 10 day space flight. Otolith-spinal reflexes were elicited by means of sudden, unexpected falls. In weightlessness, “falls” were achieved using elastic cords running from a torso harness to the floor. Electromyographic (EMG) activity was recorded from(More)
The aim of this study was to establish the relationship between selected physiological variables of rowers and rowing performance as determined by a 2000 m time-trial on a Concept II Model B rowing ergometer. The participants were 13 male club standard oarsmen. Their mean (+/- s) age, body mass and height were 19.9+/-0.6 years, 73.1+/-6.6 kg and 180.5+/-4.6(More)
1. The presence of a form of stretch reflex, previously described in the arm by other authors, has been confirmed in the gastrocnemius muscle of the human leg. The electromyographic (e.m.g.) manifestation of this reflex occurred 120 msec (S.E. of mean = 3.5 msec) following a sharply applied, and maintained, dorsiflexing force to the foot. This form of(More)
1. The spike-triggered averaging (STA) method has been used to study synaptic connections of nine spindle group II afferents from medial gastrocnemius to 151 motoneurons of leg muscles in the cat. 2. EPSPs were found in 40 cells, predominantly of triceps surae with latency from cord entry ranging from 0.3 to 4.2 ms. Those with latency less than or equal to(More)
1. It was previously shown that the controlled landing from single steps to the ground is typically brought about by accurately timed motor activity, commencing before the actual landing, and completed before time would permit the participation of a useful stretch reflex response.2. To investigate further the validity of this conclusion, subjects were(More)
A short-latency electromyographic response has been demonstrated in the human gastrocnemius during unexpected falls (11). The hypothesis that it is a form of otolith-spinal reflex has been tested in the cat. Electromyographic activity was measured in four muscles while suddenly and unexpectedly dropping a series of six cats from 50 cm above the ground. In(More)
Unusual vestibular responses to head movements in weightlessness may produce spatial orientation illusions and symptoms of space motion sickness. An integrated set of experiments was performed during Spacelab 1, as well as before and after the flight, to evaluate responses mediated by the otolith organs and semicircular canals. A variety of measurements(More)
BACKGROUND Watt et al. (15) and Young et al. (17) have demonstrated that during prolonged microgravity, large errors can be made when pointing at memorized targets in the absence of vision. However, those experiments could not distinguish between errors caused by not knowing where the arm was pointed and errors caused by not knowing target location. The(More)
The 4 payload crew members of the Spacelab Life Sciences 9-day space flight in 1991 were subjected to limited vestibular testing in flight as well as pre and post flight. Major differences in individual "perceptual style" appeared in their reaction to the visual-vestibular stimuli in the rotating dome experiment, and especially in the extent to which(More)