Cognitive performance during prismatic displacement as a partial analogue of "space fog".

Background: The fact that microgravity adaptation and recovery from the cognitive deficit of "space fog" follow approximately the same time course raises the possibility that they are related to one another. Two experiments tested this hypothesis.

Methods: Because microgravity adaptation is unique to outer space, we investigated the Earth-based analogue of adapting to prismatic displacement. Participants' goal was to overcome the disruptive effects of this optical distortion on the speed and accuracy with which they negotiated an outdoor "slalom course." The experimental group had the additional assignment of performing a cognitive task. In Experiment 1, the task was making serial subtractions of 7 from an initial starting number, while in Experiment 2 it was to repeat back a sequence of high- and low-pitched tones.

Results: In neither experiment did adaptation influence cognitive performance or vice versa. That is, the improvement of slalom-walking performance attributable to prism adaptation was the same with or without a concurrent cognitive task and cognitive task performance was unaffected by exposure to prismatic displacement. Instead, the experiments revealed that both prism exposure and cognitive task performance reduced participants' walking speed.

Conclusions: These results suggest that the pace of astronauts' visual-motor behavior in space will be slowed by both microgravity and the cognitive tasks they must perform. They also bolster the use of prism adaptation as an inexpensive, ground-based means of studying microgravity adaptation.