Encoding and decoding of connected discourse during altered states of consciousness.

Inhaling nitrous oxide (N2O) impairs verbal memory recall, especially when sentences are low in semantic context. Among 44 male U.S. Navy corpsmen aged 20–29, those who breathed N2O for 10 minutes made more errors repeating sentences than those who breathed air. Task complexity caused the most errors. Volunteers could partly compensate for variations in syntax and the gas state, but low semantic quality strongly hurt performance. The combination of N2O, low syntax, and low semantic context produced the highest error rate, while air, high syntax, and high semantic context produced the lowest.

Study at a glance

Abstract

The following hypotheses were investigated in a study of memory recall and an altered state of consciousness: (a) A direct relationship was expected between the magnitude of correct responses and task complexity. (b) Semantic context variation was expected to cause greater impairment in verbal processing than variation in syntactic constraints. (c) Under N2O fewer correct responses in verbal processing were expected to be made. Forty-four volunteers, male corpsmen in the U. S. Navy between the ages of 20 and 29, were randomly divided into two equal groups: a nitrous oxide group and an air group. After breathing either N2O or air for 10 minutes, Ss were required to repeat pairs of taped sentences of high syntax/high semantic context to low syntax/low semantic context. Responses were scored for errors. All three hypotheses were accepted. Task complexity caused the greatest magnitude of errors. Ss were able to compensate for variations in syntax and in the gas state, but low semantic quality strongly affected performance. The factors interacted in powerful ways to produce differential response errors from a low error rate for air/high syntax/high context to a high error rate for N2O/low syntax/low context.