Nitrogen narcosis measured by dual-task performance

Two hyperbaric studies tested detrimental effects of 188-ft sea water gauge (fswg) air pressure. In each experiment, 8 males aged 22-32 yrs, qualified for hyperbaric exposures, executed single-task controls of a choice reaction time (RT) task and a pursuit tracking task, as well as their dual-task combinations. All tasks were tested 0, 10, and 188 fswg. Exp I was designed to measure the effects of nitrogen narcosis on 2 successive weekly dives. No improvement specific to the 188 fswg depth was found on the 2nd dive. It is concluded that the prior exposure did not result in measurable adaptation to narcosis. At 188 fswg, the rate of information transmission in the choice RT task was slowed and tracking error increased. Dual-task requirements resulted in poorer tracking but left choice RT performance unaffected. In Exp II, half of the Ss stopped at 19 fswg before proceeding to depth. They showed a decrement in performance at 188 fswg equal to, or greater than, that found for the remaining Ss, who used the standard procedure of descending to depth directly.