A twofold inquiry into the implication of the theory of biorhythms as a significant variable in human task performance and decision strategies under time-stress conditions

Abstract

This investigation of the theory of biorhythms (TOB) developed by Fleiss-Swoboda-Teltscher was a dual design: a macro analysis involving a single measurement for each unit of observation in a large sample, and a micro analysis involving longitudinal measurements for each unit of observation in a small sample. In both studies, decision making occurred under conditions of stress, and recorded measurements were correlated with TOB. Neither study contributed to the support of TOB. The macro analysis investigated 728 motorcycle accidents classified as single party, male, human error. For validity, accidents were randomly assigned to one of two groups. Accidents in each group were assigned to one of 27 possible joint biorhythm positions on the accident date. For each group, accidents were first assigned using Thommen's critical days scheme and then reassigned using Nett's scheme. The log-likelihood ratio test statistic was selected over the chi-squared test statistic because it permitted analysis of smaller samples. The null hypothesis was that accidents occurred by chance (the actual number of accidents would not significantly deviate from the number expected from TOB). The null hypothesis was tested for each group under each classification scheme. In all four cases, the null hypothesis could not be rejected at the five percent level of significance. In only one test was the null hypothesis rejected at the ten percent level of significance. In the micro analysis 41 subjects participated in fourteen test sessions uniformly scheduled over seventy days. At each session ten tests measured intellectual/physical performance and emotional state. Four models describing varying characteristics of TOB were formulated; each model considered first and second order learning effects. Two versions of each model were considered: hypothesized (o) and unrestricted (*). For each version and model the objective function was to minimize the unexplained sum of squares (SS) -- equivalent to maximize the coefficient of determination (population, p^2, or sample, r^2). The hypothesized version employed period and phase position specified by TOB...