Phasic influences on psychometric measures during the menstrual cycle: Implications for the construct integrity of the locus of control dimension

Thirty healthy female volunteers with normal menstrual cycles participated in a study to ex-amine the influence of menstrual cycle phase on locus of c ontrol (LC) orientation. LC measures were taken on the follicular, luteal a nd premenstrual phase of the cycle. It was found that menstrual cycle phase had little effect on LC orientation suggesting chat previously observed LC differences across the cycle in dysmenorrhea and premenstrual syndrome suf ferers cannot be generalized to a normal non-clinical population. Surprisin gly, it was further found that no significant statistical relationship was found between the two LC measures used, in spite of the finding that, indiv idually, each LC measure intercorrelated highly significantly across the me nstrual cycle. Since one of the LC scales was derived theoretically, and th e other LC scale used was derived from clinical practice, the findings are discussed in relation to the theory-practice divide and the prima facie val ue of self-report LC measures.