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Posts archived in Intelligence and learning


identical-twins

Identical twins – helping research methods stay ethical

An excellent article on the British Psychological Society’s Research Digest blog considers why it is so difficult to establish cause and effect in studies of links between intelligence and education. One difficulty is that it is not ethical to remove one randomly-selected group of children from education to test what happens to their intelligence levels in later life. Another is that genetic differences between children may have as much to do with later differences in their IQ scores as the education they receive. Again, it seems unlikely that psychologists will consider it ethical (or practical) to clone children in order to remove this genetic influence from research on education and intelligence.

Such is the ingenuity of psychologists, however,  that studies have tackled both these difficulties without unethical methods being resorted to. So for example, identical twins have pretty much 100% genetic similarity, so any differences in reading ability between twins should be due to differing environmental influences.

The difficulty then comes in establishing what those differing environmental influences are. The researchers writing the article could identify an effect, but could only speculate on the possible causes – and all the possible alternative explanations for their findings. But they hope that by using twin-studies in this way, they are ‘edg[ing] further up the causal ladder, away from the basic correlational study’.

According to palaeontologists (scientists who study fossils), over the last 20,000 years the average volume has been decreasing – possibly losing as much as 150cc (a chunk the size of a tennis ball). One possible explanation is related to the fact that brain size is correlated with body size. Humans have become smaller over the millennia. Early  humans were much brawnier for hunting and also for dealing with cold climates, but now we are smaller and therefore our brains have become correspondingly smaller.

Another possibility is that brain structure has become more efficient so that fewer cells and connections are needed. There is certainly evidence that brain size does not equate to intelligence and that what may be more significant is the organisation of the brain (see A2 Complete Companion page 131). This is the suggestion made by John Hawks, who argues that the brain consumes a lot of energy therefore individuals with intelligence and a smaller brain would be selected for.

On the other hand, cognitive psychologist David Geary proposes that our brains are getting smaller because we are becoming more stupid. The argument goes that brain size is related to social complexity but in a surprising way. Read the rest of this entry »

Surprisingly the only non-vertebrate animal protected by the Animals (Scientific Procedures) Act is the octopus. Why? More and more research is pointing to the octopus as a relatively intelligent animal. They can remember mazes, use tools, solve complex problems and appear to have a rudimentary consciousness. Conducting research on their brains appears quite difficult as they can shut off blood supplies to an area of their body or brain at will. One researcher thought he had anaesthetised an octopus and placed an electrode in its brain … and then found the animal reached up and pulled the electrode out. Another octopus regularly short-circuited the light in its tank by squirting water at it (source).

Octopi brains are quite developed – they are lateralised, like mammalian brains, and also highly folded, greatly increasing the surface area. Some neurons are minaturised permitting more to be packed in.. One researcher, Jennifer Basil, plans to start looking for mirror neurons in a related species, the nautilus. If she finds them it might mean these ancient cephalopods are not as stupid as they look – they may be able to infer the emotional states of another animal, which might explain why one researcher said octopi seem to know what he is thinking. Spooky.

Humans have exceptionally large brains; taking body size into account the human brain is seven times larger than those of other mammals. It has long been assumed that the benefit of this large brain is high intelligence A Brazilian, Suzana Herculano-Houzel, has recently challenged this. There are a number of small brained animals who are very intelligent, such as the capuchin monkey, and also large brained animals who are low on smarts. Herculano-Houzel wondered if it was a mistake to compare brains in terms of size (allowing for brain:body weight ratio). She thought brains from different groups of animals might be organised differently and this might matter more. To investigate this she calculated the number of neurons in each species’ brains – no one had done this before.  Up to this point they had just estimated the number of neurons in a brain. She devised a fractionator method to do this and found human brains contain 86 billion neurons.

Comparing the neuron counts of different animals what she found was that human brains had more neurons per brain volume than say rodents – but not more than other primates. Herculano-Houzel says people have been overemphasising the importance of body weight in Read the rest of this entry »

Meat was an important source of nutrition for ancestral humans (as it is today, MacDonalds aside). It has been suggested that the importance of meat meant that men often traded it for other favours such as forging allegiances or for sex  (Stanford, 1999 – see pages 101, 130 and 131 of our A2 Complete Companion). Observations of animal and human behaviour have been used to support this ‘meat for sex’ hypothesis, however a recently published study says the suggestion is baseless. Gilby et al. (2010) conducted an observational study of chimpanzees over a 28 year period (see here and here) and found no evidence that males hunted more when females were most fertile, nor were they more likely to share meat with fertile females. However there continues to be evidence that supports the meat for sex hypothesis (see here). This study  by Gomes and Boesch (2006) found direct evidence of meat exchange in another study of wild chimpanzees. It may be that males exchange meat on a long-term basis i.e. they don’t do it just when a female is fertile but provide meat continually so they can take advantage of fertile periods when they occur.

Dreams, drugs, intelligence, memory, infant brains, psychoanalysis, human evolution and many more – Loads of online broadcasts from Melvyn Bragg’s ‘In Our Time’ Radio 4 series to be found here – all free – it makes one proud to be a licence payer….

Loads of interesting material for sale on Ebay, including this IQ picture puzzle test from 1918.

Train your baby to grow up a genius? That is the idea behind a load of commercial stimulus materials such as the Disney Baby Einstein videos, books, flashcards, toys, and so on (seemingly anything marketable ). We have described these products on page 219 of the A2 Complete Companion, along with a study that showed that watching the DVDs can lead to a poorer developmental outcome. Now Disney is refunding the cost of the videos to anyone who purchased them!! The refunds are because a range of studies have shown that watching TV is potentially harmful for the under-2s, and linked early TV watching to attentional problems at around age 7. It would be interesting to know if the brain’s developing connections are affected by environmental input, something which has very tricky ethical issues but which might be abe to be done as a natural experiment. The emphasis on stimulating cognitive development is still on positive adult-child interactions.

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“For as long as IQ tests have existed, there has been a steady, progressive and ubiquitous improvement in the average scores people achieve at a given age, mainly because of a raising of the lower scores. On average, IQ is increasing by 3 per cent per decade. The effect is so strong that it implies that half of children in 1932, if given today’s tests, would score under 80 – the threshold for mental retardation.

Known as the Flynn Effect (after James Flynn), this phenomenon was initially dismissed as a result of changes in tests, or a reflection of better schooling. But the facts do not fit. Improvement is most marked in the types of test that relate least to educational content. Moreover, the effect is weakest in the cleverest children. It is a levelling-up phenomenon that results in a happy increase in equality.

After much agonising debate among psychologists, three explanations seem to make the most sense. The first is that (despite fast food) most children now get sufficient essential nutrients, vitamins, amino acids and oils to allow their Read the rest of this entry »