Over the last few years the BBC has broadcast an excellent series on research studies that have changed our understanding of the human mind, presented by Claudia Hammond (some of you may have heard her speak at a recent student conference in London). The BBC has now decided to make them all available for download here. Topics covered include Bandura’s Bobo doll study, Rosenhan’s Pseudo-patient study, Kohlberg’s Heinz dilemma, The Hawthorne effect, Mary Ainsworth’s research. In total there are 15 programmes each 28 minutes in length. On Sunday 17 April there is a new series starting with a programme on Elizabeth Loftus and Eyewitness Testimony.
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The American Psychiatric Association (APA) has been arguing in favour of ECT as a safe treatment for severe mental illness, according to a short piece in the current issue of the BPS magazine The Psychologist. The APA claims that ECT is effective 80% of the time and there is no evidence for any associated brain damage.
On the other hand a recent review by Bentall and Read (2010, see here) concluded that any benefits of ECT, when they arise, are minimal, short-lived and come with a significant risk of memory impairment and a slight risk of death. This conclusion was based on a review of studies over the last 60 years where the use of ECT for depression or schizophrenia was compared to a placebo control procedure. Bentall and Read’s final word is that the evidence is so poor that it’s use cannot be scientifically-justified.
In Chapter 1 (Biological rhythms and sleep) of our A2 Complete Companion there is a contradiction (kindly
pointed out by Ruth Bailey of Akeley Wood School). On page 13 the text says that dolphins don’t have REM sleep whereas on page 14 the graph indicates a significant amount of REM sleep in dolphin. So which is correct?
The data for the graph was taken from a study Lyamin et al. (2004) of one dolphin, reported by the Phylogeny of Sleep Project (you can see the dolphin data here). As pointed out in our textbook much of the data about sleep is actually derived from very small samples and research conducted under poorly controlled conditions.
All of the other dolphin studies given by the Phylogeny of Sleep Project did not record the amount of REM sleep which is why we used the data from Lyamin et al. However this data is misleading as the general view appears to be that (REM) sleep is either absent in cetaceans (e.g. dolphins) or occupies an extremely small proportion of the day – an absolute maximum of 15 min each day (Manger et al., 2003). In fact a recent paper published by Lyamin et al. (2008) states that ‘We find that for cetaceans sleep is characterized by USWS [unihemispheric slow wave sleep] [and] a negligible amount or complete absence of rapid eye movement (REM) sleep’.
Type 1 and 2 errors are not easy to understand and recently one student (thank you Laura Hastings) wrote in to ask if we were also confused (!) and had made a mistake with Type 1 and 2 errors in our AQA A A2 book. Fortunately we hadn’t but the explanation was a bit unclear. On page 266 (Chapter on Anomalistic Psychology) it says:
Causal thinking evolved because it allows people to understand and control their environment, i.e. to be able to predict that, for example, if you eat a red mushroom you will die. This causal thinking is adaptive but may sometimes lead to Type 1 errors – where you believe something is true when it isn’t, for example you believe that tying your shoes laces twice causes luck.
The problematic phrase is ‘where you believe something is true when it isn’t’. Laura was confused because a Type 1 error is defined on page 300 as ‘when a null hypothesis is rejected when it is true’. So it sounds like we got it wrong – but in fact both Type 1 and Type 2 errors are ‘where you believe something that isn’t true’:
- Type 1 error (false positive) – you believe the null hypothesis isn’t true (and reject it) but in reality the null hypothesis is true. So, in the case of shoe laces you believe shoe laces and luck are linked but, in reality, there is no link. Or you avoid mushrooms for ever after because you think they will make you die but this link is mistaken.
- Type 2 error (false negative) – you believe the null hypothesis is true (and accept it) when in reality the null hypothesis is not true. In the case of shoe laces and luck, you believe tying your shoe laces twice has no effect on luck but in fact it has. Or you believe that red mushrooms don’t cause death but they do.
The point is that we err on the side of making Type 1 errors (and believing erroneous causal relationships) because we might otherwise make Type 2 errors.
As for the text book, it would be better if it said ‘Type 1 errors – where you believe the null hypothesis is wrong when it isn’t’.
Interesting range of online experiments involving bio-motion here
A small study of Canadian infants and toddlers found that those who slept most at night were making significantly more progress in executive functions than those who slept less at night, even if the latter group also had daytime sleep. These functions include impulse control, memory and mental flexibility. The researchers controlled for parents’ education and income and children’s general cognition, but the link between night-time sleep and development of cognitive skills remained. These finding support similar research findings on schoolchildren.
Might this also apply to older childern and adults? That would be interesting to know!
Annie Bernier, Stephanie M. Carlson, Stéphanie Bordeleau, Julie Carrier. Relations Between Physiological and Cognitive Regulatory Systems: Infant Sleep Regulation and Subsequent Executive Functioning. Child Development, 2010; 81 (6)
It’s been known for ages that information on light levels is passed from the two retinas via a special small nerve from each eye to the SCN, but the mechanism of this is now more clear. As well as rods and cones, cells which are sensitive to light and give us black-and-white and colour vision there is a third type of light-sensitive retinal cell. These are far less in number than rods and cones, and react to light by expressing the pigment melanopsin, so they are known as mRGCs (melanopsin-expressing retinal ganglion cells). Not only do these cells send information to the SCN but they also control pupil size. And now it seems they also contribute to our visual image formation as axons from the mRGCs have been traced onwards from the SCN to visual processing centres. What does this imply? It gives some idea of how seriously sight impaired people can still detect levels of brightness, plus the possibility in the future of engineering melanopsin-expressing cells to improve or restore sight.
Fred Rieke, Timothy M. Brown, Carlos Gias, Megumi Hatori, Sheena R. Keding, Ma’ayan Semo, Peter J. Coffey, John Gigg, Hugh D. Piggins, Satchidananda Panda, Robert J. Lucas. Melanopsin Contributions to Irradiance Coding in the Thalamo-Cortical Visual System. PLoS Biology, 2010; 8 (12)
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A proposal to classify happiness as a psychiatric disorder
December 6, 2010 by Adrian Frost.
It is proposed that happiness be classified as a psychiatric disorder and be included in future editions of the major diagnostic manuals under the new name: major affective disorder, pleasant type. In a review of the relevant literature it is shown that happiness is statistically abnormal, consists of a discrete cluster of symptoms, is associated with a range of cognitive abnormalities, and probably reflects the abnormal functioning of the central nervous system. One possible objection to this proposal remains–that happiness is not negatively valued. However, this objection is dismissed as scientifically irrelevant.
via null device
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Evolutionary Psychology explains why men are better at Scrabble
December 2, 2010 by Adrian Frost.
For a quarter-century, women have outnumbered men at Scrabble clubs and tournaments in America, but a woman has won the national championship only once, and all the world champions have been men. Among the world’s 50 top-ranked players, typically about 45 are men.
The top players, both male and female, point to a simple explanation for the disparity: more men are willing to do whatever it takes to reach the top. You need more than intelligence and a good vocabulary to become champion. You have to spend hours a day learning words like ‘khat,’ doing computerised drills and memorising long lists of letter combinations, called alphagrams, that can form high-scoring seven-letter words.
. . .
The guys who memorise these lists have a hard time explaining their passion. But the evolutionary roots of it seem clear to anthropologists like Helen Fisher of Rutgers University.
‘Evolution has selected for men with a taste for risking everything to get to the top of the hierarchy,’ she said, ‘because those males get more reproductive opportunities, not only among primates but also among human beings. Women don’t get as big a reproductive payoff by reaching the top. They’re just as competitive with themselves – they want to do a good job just as much as men do – but men want to be more competitive with others.’”
From New York Times
Images from Adverblog
It seems that you can tell whether a person is promiscuous or monogamous just by looking at the fingers! Well, maybe it doesn’t work for individuals but researchers curious about human evolution have used finger length to make an educated guess about some of our distant ancestors’ mating habits.
According to evolutionary theory male characteristics such as aggressiveness and competitiveness are more likely in promiscuous species than monogamous ones. Looking at fossil skeletons we can therefore suggest that Australopithecus, which lived three to four million years ago was monogamous whereas an even earlier group, Ardipithecus, was highly promiscuous – all because of their finger length!
Of course it isn’t the finger length that causes sexual behaviour – it is levels of the male hormone androgen. Higher aggression and competitiveness in males is related to intrasexual selection (the more androgens the more competitive) and is also related to higher levels of androgens. An effect of higher
Finger length ratios have been linked to lots of other things, such as numeracy and literacy (see The A2 Complete Companion page 288).