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Menstrual-cycle synchrony: problems and new directions for research
1Department of Psychology, University of California, Davis, 95616, USA. jcschank@ucdavis.edu
Summary
Menstrual synchrony studies may be flawed. Methodological errors and participant recall biases can create artifactual synchrony, suggesting cycle variability might be advantageous for mate choice.
Area of Science:
- Human Physiology
- Evolutionary Biology
- Social Psychology
Background:
- The phenomenon of menstrual synchrony, where women's menstrual cycles align, has been reported since 1971.
- Recent studies by Weller, Weller, and colleagues claim increasingly strong evidence for menstrual synchrony.
Purpose of the Study:
- To analyze the methodology of recent menstrual synchrony studies.
- To demonstrate how methodological flaws can artifactually produce synchrony.
- To explore the potential adaptive significance of menstrual cycle variability.
Main Methods:
- Analysis of recent menstrual synchrony research methodology.
- Two simulation studies were conducted to test for artifactual synchrony.
- Identification of specific error categories in cycle onset difference calculations and participant data collection.
Main Results:
- Two categories of errors were identified that can create artifactual synchrony.
- Errors include inaccuracies in calculating expected cycle onset differences with variability.
- Participant-reported data, including recall bias and information exchange, can introduce errors.
Conclusions:
- Reported menstrual synchrony may be an artifact of flawed methodology and data collection.
- Cycle variability, rather than synchrony, might be a biologically advantageous state.
- Menstrual cycle variability could play a role in female mate choice strategies.