AQA Psychology for A Level Year 2 - Student Bk

Concepts: The Basic Rest-Activity Cycle Much evidence from EEG recordings suggests the existence of the 90-minute cycle during sleep (see facing page). However, Kleitman (1969) also suggested that a similar 90-minute rhythm cycle continues during waking hours. He called this the Basic Rest–Activity Cycle (or BRAC for short) which is characterised by a period of alertness followed by a spell of physiological fatigue. This occurs across a 90-minute cycle which then recurs during the course of the day. Anecdotal evidence supports the existence of BRAC such as the frequent observation that students find it difficult to concentrate for periods longer than 90 minutes at a time. Similarly, most people will require a (coffee) break in order to divide up their working morning and also their afternoon. In a widely cited study of prodigious violinists, Ericsson et al . (1993) found that the best performers tended to practise for three sessions during the course of the day, each session lasted no more than 90 minutes, and there was a break between each in order to ‘recharge’. Question Explain what type of rhythm BRAC is. Justify your answer. @ookx hs @ookx hs 1. With reference to an example, define what is meant by an ultradian rhythm . [3 marks] 2. Describe one study that investigated an infradian rhythm. [4 marks] 3. Discuss research into infradian and/or ultradian rhythms. [16 marks] Check It Methods: SAD In a study, patients suffering from seasonal affective disorder (SAD) were divided into two different groups: Group 1 received phototherapy treatment. Group 2 received no treatment. The progress of the two groups was studied for the same length of time during the winter period. At the end of the study, all patients were required to complete a questionnaire which assessed their mood and the difference in mood scores between the two groups was calculated. Question 1. Explain the purpose of Group 2 in the investigation above. ( 3 marks ) 2. Which statistical test would be most appropriate to analyse the difference in mood scores between Group 1 and Group 2 in the investigation above? Justify your answer. ( 4 marks ) (See page 70) @ookx hs @ookx hs Animal studies Much of the knowledge of the effects of pheromones on behaviour is derived from animal studies. The role of pheromones in animal sexual selection is well-documented. For instance, the fact that sea urchins release pheromones into the surrounding water so other urchins in the colony will eject their sex cells simultaneously. In contrast, evidence for the effects in human behaviour remains speculative and inconclusive (and this includes the, so far unproven, idea that transmission of pheromones between humans may act as an aphrodisiac!). Consider: What are the issues with applying the findings from animal studies to human behaviour in pheromone research – and psychology generally? Practical application – SAD One of the most effective treatments for SAD is phototherapy. This is a lightbox that simulates very strong light in the morning and evening. It is thought to reset melatonin levels in people with SAD. This relieves symptoms in up to 60% of sufferers (Eastman et al . 1998). However, the same study recorded a placebo effect of 30% using a ‘sham negative-ion generator’ (participants were told it was another form of treatment). This casts doubt on the chemical influence of phototherapy. Consider: What is the ‘placebo effect’? Explain why this is a problem in treatment studies particularly. Evaluation e X tra According to Ercisson et al. and the basic rest activity cycle, the key to world class violin playing is having a break every 90 minutes. Now, that, I can do . . . Evaluation Evolutionary basis of the menstrual cycle Menstrual synchrony, of the kind observed in the McClintock study, is thought by many to have an evolutionary value. For our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant around the same time. This would mean that new-borns could be cared for collectively within a social group increasing the chances of the offspring’s survival. The validity of the evolutionary perspective has been questioned by some. Jeffrey Schank (2004) has argued that if there were too many females cycling together within a social group, this would produce competition for the highest quality males (and thereby lowering the fitness of any potential offspring). From this point of view, the avoidance of synchrony would appear to be most adaptive evolutionary strategy and therefore naturally selected. Methodological limitations in synchronisation studies Criticisms have been made of early synchronisation studies and the methods employed. Commentators argue that there are many factors that may effect change in a woman’s menstrual cycle, including stress, changes in diet, exercise, etc., that might act as confounding variables . This means that any supposed pattern of synchronisation, as seen in the studies by McClintock and others, is no more than would have been expected to occur by chance. In addition, research typically involves small samples of women and relies on participants self-reporting the onset of their own cycle. Perhaps more critically, other studies (e.g. by Trevathan et al. 1993) failed to find any evidence of menstrual synchrony in all-female samples. Evidence supports the idea of distinct stages in sleep A landmark study by William Dement and Nathaniel Kleitman (1957) monitored the sleep patterns of nine adult participants in a sleep lab. Brainwave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol. REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and participants woken during dreaming reported very accurate recall of their dreams. Replications of this investigation have noted similar findings, though the small size of the original sample has been criticised by some. Nevertheless, this study suggests that REM (dream) sleep is an important component of the ultradian sleep cycle. Practical activity on page 52 Biological rhythms: Infradian and ultradian rhythms 49 •