Impairments of manual tracking performance during spaceflight: more converging evidence from a 20-day space mission

Studies of human performance during spaceflight have consistently revealed degradations of manual tracking performance in space. The present investiga tion analysed these performance decrements in more detail by applying frequ ency-response analyses of tracking performance. It was hypothesized that tr acking impairments result from two factors: at an early adaptation phase in space they primarily reflect effects of microgravity on human visuo-motor processes, whereas later into the mission they are also caused by impairmen ts of attentional processes induced by cumulative workload and fatigue. In order to investigate this hypothesis, performance of one cosmonaut in a fir st-order unstable tracking task was repeatedly assessed before, during and after a 20-day space mission. Single-case statistical analyses revealed the following effects: tracking performance declined at the first assessment i n space and in two later inflight sessions compared to pre-flight baseline. Whereas the early tracking decrement was mainly due to an increase of the effective time-delay during tracking and accompanied by only minor changes of mood or workload, one of the later inflight impairments was due to an in crease of effective time-delay, a decreased tracking gain, and an increase of tracking remnant, and both were associated with considerably higher work load ratings. This pattern of effects supports the two-factor hypothesis.