Effects of inert gas narcosis on rehearsal strategy in a learning task.

Two experiments were conducted to examine the effects of 35% nitrous oxide (N2O) on rehearsal strategy while learning a list of words in a free-recall paradigm. In experiment 1, the subjects learned the list while rehearsing the words aloud. Learning was slowed and an analysis of the recorded rehearsal protocols revealed a decrease in the overall rate of rehearsal. In addition, there was a decrease in both the number of words rehearsed together and the proportion of words rehearsed from earlier serial positions in the list. In experiment 2, the subjects were required to follow a different rehearsal protocol which was identical for both N2O and the air-breathing control. They had no difficulty following this protocol, but learning was still slowed. These results demonstrate that rehearsal strategies may be modified by narcosis but can be manipulated experimentally. This is consistent with the hypothesis that strategic variables play an important role in the slowed processing model of inert gas narcosis.