PSYCHOMOTOR PERFORMANCE DURING A 28 DAY HEAD-DOWN TILT WITH AND WITHOUT LOWER-BODY NEGATIVE-PRESSURE

Several factors may affect psychomotor performance in space: sensory-m otor changes, sleep disturbances, psychological modifications induced by the social isolation and confinement. However, psychomotor performa nce is difficult to assess. A battery of standardized and computerized tests, so-called ''Automated Portable Test System'' (APTS) was devise d to ascertain the cognitive, perceptive and motor abilities and their possible fluctuations according to environmental effects. Antiorthost atic bedrest, often used to simulate weightlessness, (particularly car diovascular modifications) also constitutes a situation of social conf inement and isolation. During two bedrest experiments (with head-down tilt of -6-degrees) of 28 days each, we intended to assess psychomotor performance of 6 males so as to determine whether: on the one hand, i t could be altered by remaining in decubitus; on the other, the Lower Body Negative Pressure sessions, designed to prevent orthostatic intol erance back on Earth, could improve the performance. To accomplish thi s, part of the APTS tests as well as an automated perceptive attention test were performed. No downgrading of psychomotor performance was ob served. On the contrary, the tasks were more accurately performed over time. In order to assess the experimental conditions on the acquisiti on phase, the learning curves were modelled. A beneficial effect of th e LBNP sessions on simple tests involving the visual-motor coordinatio n and attention faculties can only be regarded as a mere trend. Method s used in this experiment are also discussed.