Infradian Rhythms Flashcards
What are Infradian Rhythms?
Biological rhythms with a cycle length of more than 24 hours
What are 2 examples of Infradian Rhythms?
- The Menstrual Cycle
- Seasonal Affective Disorder (SAD)
What is the Menstrual Cycle?
The length of time between the first day of a woman’s period and the day before her next
How long does the Menstrual Cycle typically last?
28 days
What are the endogenous pacemakers in terms of the Menstrual Cycle?
The 4 key hormones that govern it:
- Oestrogen
- Progesterone
- LH
- FSH
What is one proposed exogenous zeitgeber in terms of the Menstrual Cycle?
Pheromones released from other women
Describe Stern & McClintock’s Study into the synchronisation of menstrual cycles
- Studied 29 women with a history of irregular periods
- Gathered samples of pheromones from several of the participants at different stages of their menstrual cycle via a cotton pad placed under their arm
- Froze and treated the pads with alcohol
- Rubbed them onto the upper lip of the other participants
What percentage of participants in Stern & McClintock’s Study experienced changes in their menstrual cycles that aligned them more closely with the cycle of their ‘odour donor’?
68%
What two suggestions have made been made regarding the synchronisation of menstrual cycles and evolutionary psychology?
- McClintock suggested that male pheromones act as an exogenous zeitgeber of sorts by resetting the endogenous pacemaker that governs the menstrual cycle, meaning women have shorter periods and therefore are fertile more of the time, linking to the fact that women who work with men tend to experience shortened menstrual cycles
- Evolutionary psychologists have suggested that the synchronisation of menstrual cycles provides an evolutionary advantage as it results in the synchronisation of pregnancies, meaning that childcare can be shared among multiple mothers who have children at the same time
What type of psychology can research into the Menstrual Cycle be linked to?
Evolutionary psychology
Who also found similar results to Stern & McClintock in terms of the menstrual cycle?
Russell et al, who also rubbed the pheromones of one group of women onto the upper lips of another group and found that their cycles synchronised despite them being separate
What did Penton-Volk et al find in terms of women’s preferences in terms of their menstrual cycle?
- That women expressed a preference for feminine features at the least fertile stage of their menstrual cycle, and a preference for more masculine features at their most fertile point
- This suggests the importance of studying infradian rhythms in relation to human behaviour
Can evolutionary psychology be falsified?
No
Who found conflicting findings to Stern & McClintock?
Trevathan
Why can’t cause-and-effect be established in terms of research into the Menstrual Cycle?
Much research conducted are field studies, and therefore don’t maintain a high level of control over potential confounding variables
