On controlling inert gas narcosis.

Ten subjects breathed experimental mixtures of 20% and 35% nitrous oxide (N2O) balanced with oxygen and then aligned a pointer with a target using vision, kinesthesis, or combinations of these senses. In a prior session the subjects had been trained on the task with feedback while breathing N2O. The results showed that N2O did not influence variable error (VE), constant error, (CE), or absolute CE, but perceptual conditions influenced VE and absolute CE. These results suggest that the demonstration by Legge (1965) of changes in the variability and accuracy of matching on this task under N2O are indicative of changes in response bias and/or attention rather than perceptual sensitivity. It is argued that narcosis slows rather than distorts information processing. Slowing is accompanied by strategic changes that may be maladaptive. This suggests that, contrary to conventional wisdom, the safety and efficiency of divers exposed to narcosis could be improved with training.