Controlling for Mutual Exchange of Information
Weller and Weller’s later studies assumed that “state synchrony” had already been achieved (that is, cycles were assumed to have synchronized a long time ago), rather than that cycles were in the process of becoming synchronized (as in the original 1971 McClintock study).
If, as Weller and Weller argue, there is low cycle length variability in already-synchronized women, AND, if state synchrony implies “small random fluctuations around the mean onset differences in succeeding months” (Schank 2001), then perhaps collecting data in a rolling fashion from “already-synchronized” women would control for mutual exchange of information.
That is, for a nine-month study, divide study participants into three groups, A, B, and C. Make sure that no roommates or close friends are in the same group together. Group A records their menstrual onsets for months 1-3; Group B months 4-6; and Group C months 7-9. Then proceed to analyze the data as if it had been collected simultaneously over a three-month period.
What are the strengths and weaknesses of the above approach? What are some other ways to control for mutual exchange of information?
The above points of contention are some, but not all, of the criticism leveled at the theory of menstrual synchrony.
However, menstrual synchrony is as much a part of popular culture as it is a scientific theory. Click here for a discussion of some of the ways menstrual synchrony is being used to interpret the past; some speculations as to why it is so popular; and why menstrual overlap, rather than menstrual synchrony, may be a more useful concept.