The Effect of Time of Day on the Reaction to Stress. Final Report.

This study obtains evidence for the effect of time of day on learning in a stressful situation. A series of five experiments were performed to assess the effects of this variable on learning using albino rat subjects. None of the experiments provide overwhelming evidence for the effect of time of day when taken alone and each leaves questions which can only be answered by empirical test. However, as a group they seem to indicate that time of day does play an important role in learning in a stressful situation. Most forms of motivation such as fear of failure in a classroom or fear of shock in the laboratory are aversive or stressful in the Thorndikian sense of an annoying state of affairs which the organism will avoid or minimize. If the comparison holds, then although the effect would vary in its specifics, time of day might also influence human learning under stress. (Author)