Human performance capability in psychomotor tasks at variable difficulty levels and physiological reactions under noise and heat conditions

The effects of noise and heat on the efficiency of human performance of psychomotor tasks at variable difficulty levels were investigated. Twenty four young, healthy volunteers with normal hearing, randomly divided into 4 equal sized groups, were tested in a climatic chamber under 4 combinations of two environmental conditions made up of noise and heat, each at two levels: 70 dB (A) (quiet), 100 dB (A) (noise): 28 degrees C (comfortable), 35 degrees C (heat). A statistically balanced procedure was followed. Three physiological variables were also recorded: Heart rate, blood pressure and body temperature. A 2 x 2 analysis of variance showed rise in the physiological variables by noise and heat respectively as well as by their interactions. Performances of the psychomotor tasks were affected differently by noise and heat depending on the difficulty levels of the tasks. The interaction of noise and heat entailed superior performance of the tasks of memory and search, two hand coordination and reaction time, at moderate difficulty levels, but no distinct interaction effect was observed on the performance of tweezer dexterity.