Methodological limitations

• These include stress, changes in diet, exercise, and age All of these may act as confounding variables.
• Critics of synchronisation studies like that of McClintock & Stern argue that there are many factors that may effect change in a woman’s menstrual cycle.
• That means that any supposed pattern of synchronisation is no more than would have been expected to occur by chance
• In addition, research typically involved small samples of women and relies on participants self-reporting the onset of their own cycle.
• Studies by Trevathan et al (1993) and others have failed to find any evidence of menstrual synchrony in all-female samples.
• Most of our knowledge of the effects of pheromones on behaviour is derived from animal studies where their role in animal sexual selection is well-documented
• One example of this is sea urchins releasing pheromones into the surrounding water so other urchins in the colony will eject their sex cells simultaneously.
• In contrast, evidence for the effects on human behaviour remains speculative and inconclusive.