Task categorization and the limits of human performance in extreme heat.

This paper examines human performance limitations in differing task categories in conditions of elevated ambient temperature. Analysis of extant data affirms that decrement in the three task categories, namely: 1.) mental and cognitive skills; 2.) tracking and 3.) dual task performance, may be expected as environmental exposure exceeds 85 degrees F, effective temperature (E.T.). Further, the systematic changes in impairment onset with tasks requiring differing levels of response complexity in varying time, E.T. conditions, are documented. These changes imply earlier heat stress related decrement in those task categories which require greater response complexity. The proposed thresholds of performance impairment are subsequently equated with absolute, physiologically noncompensable, rises in deep body temperature. Support for the notion that prescribed rises in deep body temperature may delimit efficient performance in each category is found in studies which have examined task performance in situations where deep body temperature has been independently manipulated. Performer skill level is posited as potentially most influential in the mitigation of such heat induced decrement.