Effects and aftereffects of continuous noise and computation work on risk and effort choices

Choices between risk and effort, in a format (COPE) previously shown to reflect fatigue, were obtained from subjects in noise or quiet. Both sexes were used in the experiment, half the subjects working at the Norinder arithmetic task while half rested. The COPE test took a computational form, offering choices between digit lists of differing lengths in which target sums were imbedded. The baseline choice levels were established in quiet, but half the subjects were exposed to noise during the posttest. As previously found in comparable conditions, the Norinder task showed no effect of noise. Pretest-posttest comparisons on the COPE test showed that exposure to noise, like computation work, had the predicted effect of decreasing the choice of high-probability, high-effort alternatives. The presence of noise during posttest had no overall effect on risk effort choices, although there were indications that changes of any kind in the test conditions might be a factor. The data seem difficult to explain in an arousal framework, but may be simply interpreted as showing that exposure to noise produces real fatigue.