Effects of breathing air at 4 atm abs: evidence for a change in strategy.

The effect of breathing air at 4 atm abs on two tasks was investigated. For the recognition memory task, subjects learned a list of symbols in anticipation of a recognition test. The second task was a speed test in which subjects were instructed to detect all occurrences of a given target. A signal detection analysis of performance to the recognition test showed that sensitivity index was invariant, but the criterion (beta) became stricter under hyperbaric pressure. For the speed test, the results showed that under pressure the error rate increased progressively with time while the working speed remained constant. It is argued that strategic variables may be particularly sensitive to the hyperbaric environment.