Perception of posture of short duration in the spatial and temporal domains.
Twenty normal male university students with a mean age of 21.4 years, body weight of 66.2 kg, and height of 170 cm, were asked to acquire nine postures, and in the last two they were asked to exert either pushing or pulling forces for periods ranging from 5 to 15 seconds. Their posture was recorded photographically, the duration of activities was measured using a stopwatch and the force exerted during pushing and pulling was recorded using a load cell and force monitor (ST-1). The subjects were asked to estimate their postures immediately after each activity using a three-dimensional mannequin and a line drawing on a paper according to instructions provided before. They were also asked to estimate the duration and force exerted using their judgement and record. After the completion of all activities they recorded all their estimations (except mannequin) again on the same day, a week later and four weeks later. The estimates were compared with actual values through Student's t-test Stooping and twisting were accurately estimated and recalled. Side bending, pushing, and pulling were consistently significantly different from actual (p < 0.05). Whereas the memory of posture estimates was stable for the period of study, the duration estimates deteriorated with passage of time. The force assessment during pushing activity was significantly different (p < 0.01) from actual but the pulling forces were estimated and recalled accurately.
Kumar
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Department of Physical Therapy, University of Alberta, Edmonton, Canada T6G 2G4.