Describe and Evaluate Research studies into Infradian Rhythms (24 marks)

Infradian Rhythms repeat themselves over a greater period of time - rhythms that last longer than a day. For example, they may repeat themselves weekly, monthly or even annually (known as a circannual rhythm), for example, hibernation, bird migration and many reproductive cycles. As an example of a human biological Infradian rhythm, take the menstrual cycle.

Several research studies have been done into Infradian rhythms, and how to regulate them. As we know, they are governed by endogenous pacemakers (internal cues) and exogenous zeitgebers (external cues). One zeitgeber that helps regulate Infradian rhythms is the release of pheromones (biochemical substances produced in the endocrine system and distributed throughout the blood, which is then released into the air. It often affects other individuals). Russell (1980) used pheromones to synchronise women's periods within a small group. He took the pheromones of one woman and applied them to a group of sexually inactive women by taking cotton pads that had been in the woman's armpit (on a daily basis), dissolving them in alcohol to remove any bacteria, and rubbing the cotton pads onto the group of women's upper lips. The same procedure was done on a control group, but the cotton pads were without pheromones. The participants didn't know whether they were in the experimental or the control group, to reduce experimenter effects. By the end of the experiment, 4 out of 5 women in the experimental group had menstrual cycles that synchronised within 24hours of the donor's. This shows that when several women live together (and do not take oral contraceptives), they tend to menstruate at the same time every month.
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However, this study lasted only 5 months. What about the long term effects of pheromones on Infradian rhythms? McClintock & Stern (1998) set up a 10-year longitudinal follow-up study of Infradian rhythms, following Russell's research. It involved 29 women ages between 20 and 35 with a history of irregular periods. Samples of pheromones were gathered from 9 of the women in different stages of their menstrual cycles, using the same ideas as Russell - a cotton pad in the armpit. The pads were worn for at least 8 hours to ensure that pheromones were picked up. Again, the ...

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Spelling, grammar, and punctuation are all perfectly fine, and the student includes the relevant psychological terminology such as “endogenous pacemakers (internal cues) and exogenous zeitgebers (external cues)” – what is also nice is that for these technical terms, a layperson definition is given so it is certain the reader understands what is being discussed. The standard structure that should be followed to achieve the highest marks is Introduction – Main Argument/Discussion – Conclusion, as this demonstrates the student’s ability to plan and remain focused, whilst giving the reader something easy to follow. As mentioned, this student does stick to this well, although the conclusion could be made more explicit.

As mentioned, the level of analysis provided is generally of a high level; the student demonstrates their ability to objectively see both sides of an argument as they discuss both strengths and limitations to the studies, e.g. for McClintock & Stern’s the essay reads “so we know that pheromones do work, but we still aren’t sure about how” – since they authors admit they were unsure of how the pheromones actually affected the menstrual cycle. That said, I would encourage the student to apply a bit more analysis as currently the essay seems to read about 70%t descriptive and 30% analysis, top marks would be achieved by getting a 50-50split.

The student describes numerous examples of research studies on Infradian rhythms as the question requires (e.g. Russell, 1980; McClintock & Stern, 1998; Reinberg, 1967), providing a good level of detail (including dates, methods, accurate results) - typically, the student also provides a sufficient level of analysis for these studies, discussing the potential limitations of the studies (e.g. short-term vs. longitudinal studies, sample sizes, validity) as well as the implications of their findings. The introduction nicely introduces the topic of Infradian rhythms, giving the reader some background information and clear examples (E.g. the menstrual cycle) so they are prepared for the rest of the essay. In contrast, the last paragraph is not explicitly a concluding paragraph – although it presents some good ideas and comments (e.g. As most of the studies are done in laboratories, we can say that most of the factors were very controlled and that any extraneous factors were non-existent…”, it would be clearer to start the paragraph with something simple, such as ‘In conclusion’, or ‘To summarise’, to make it explicit to the reader that this is where all the evidence will be synthesised and final judgments made.