Selective hyperthermia and reaction time

Two reaction time studies are reported in which subjects responded under conditions of selective hyperthermia. Wearing a helmet prototype, the cortical surface of the subject was thermally stressed to a level 1.11 degrees C over baseline as measured by a thermocouple placed against the tympanic membrane. In a simple choice RT task, both reaction time and response variability were decreased compared to performance in either a control or placebo condition. Latency in Neisser's visual scanning task was also shortened under conditions of this thermal stress localized in the cortical region. In both cases, there was no observed decrement in accuracy or level of performance. Enhanced human performance resulting from the maintenance of cortical temperature above the normal diurnal range is implied.