outline and evaluate infradian rhythms Flashcards
outline
An infradian rhythm is a cycle that occurs less than once in a 24-hour period.
The female menstrual cycle is controlled by monthly hormonal change which regulate ovulation, a typical cycle takes approximately 28 days (though anywhere between 24 and 35 days is generally considered normal).
All biological rhythms are controlled by 2 factors: endogenous pacemakers (body’s internal biological clock) and exogenous zeitgebers (external changes in the environment).
outline study
McClintock used a laboratory experiment, recruited 29 women with a history of irregular periods.
Samples of their pheromones (chemical substance that is produced and released into the environment) were taken at different stages of their menstrual cycle, via a cotton pad placed under their armpit for 8 hours.
The pads were then treated with alcohol and then frozen.
On day one of their next cycle, pads taken from another participant from the start of their menstrual cycle was rubbed on the upper lip of another participant.
On day 2, the same participant was given the second day’s pad from the same ‘odour donor’ and so on.
McClintock found 68% of women experienced changes to their cycle, which meant they had their period at a similar time to their odour donor.
This suggests infradian rhythms can be affected by exogenous zeitgebers as synchronisation between females (an environmental factor) caused changes to their biological menstrual cycle.
strength
A strength of the research into infradian rhythms is that it has led to practical applications, which is when the principles of biological rhythms have been applied in a real-world setting.
For example, research which has informed us of the negative effects of infradian rhythms, such as seasonal affective disorder, has allowed medical professionals to introduce treatments such as phototherapy, which stimulates a very strong light in the morning and evening.
These therapies have relieved symptoms in up to 60% of sufferers, suggesting research investigating our biological rhythms are beneficial to society.
limit
A weakness of the research into infradian rhythm is that it suffers from high extraneous variables.
This is when a method cannot easily control other variables that could affect the DV.
For example, research into infradian rhythms relies on identifying patterns of synchronisation, however, these patterns may have occurred by chance as many other factors affect a women’s menstrual cycle (such as stress, changes in diet and exercise).
Therefore, we cannot be certain that the results from these studies is due to synchronisation of infradian rhythms, decreasing the internal validity of research.
