The strength of weak touches

The BPS Research Digest covers a simple yet fascinating study on the power on lightly touching someone’s arm when trying to persuade them.

In this case, the psychology study involved a man asking women to dance or for their phone numbers.

A good-looking man approached 120 women in a night club over a period of three weeks, and asked them to dance. It was in the name of science – the man was an assistant to the psychologist Nicolas Guegen. Remarkably, of the 60 women who he touched lightly on the arm, 65 per cent agreed to a dance, compared with just 43 per cent of the 60 women who he asked without making any physical contact.

A second study involved three male research assistants approaching 240 women in the street and asking them for their phone numbers. Among those 120 women who the researchers touched lightly on the arm, 19 per cent agreed to share their number, compared with 10 per cent of the women with whom no physical contact was made.

Christian has a fantastic talent for finding really intriguing studies and this is a particularly good example.

Have a look at his article for more on why this effect might occur.

Link to BPSRD on ‘The power of a light touch on the arm’.

Selling disgust

An article in Time magazine discusses how an understanding of the psychology of disgust is being applied to selling products and the arrangement of items in supermarkets.

One key finding has been that disgust is heavily linked to ideas of contamination and this holds even when there’s no risk – just the idea is enough.

For example, people are less likely to want to put a plastic spoon in their mouth that has touched fake plastic vomit, despite the fact that it is no more risky than putting a spoon in your mouth that has touched other plastic spoons in the packet.

Psychologists Andrea Morales and Gavan Fitzsimons has discovered that this principle applies to consumer products that are linked to things that can trigger disgust – rubbish bags, nappies, toilet paper and so on.

Crucially, the contamination principal works here, so people view things less favourably that have been near these products.

Strong preferences were just what the subjects exhibited. Any food that touched something perceived to be disgusting became immediately less desirable itself, though all of the products were in their original wrapping. The appeal of the food fell even if the two products were merely close together; an inch seemed to be the critical distance. “It makes no sense if you think about it,” says Fitzsimons. More irrationally still, the subjects were less comfortable with a transparent package than an opaque one, as if it somehow had greater power to leak contamination. Whatever the severity of the taint, the result was predictable…

“More and more stores organize products by category,” says Morales, “so you have a baby aisle, for example, with diapers and wipes and baby food all together.” Supermarkets might want to rethink that arrangement.

Link to Time article ‘The Science of Disgust’.

Dispelling ghostly images with electromagnets

In a study investigating how the brain generates paranormal experiences and psychotic states, researchers used strong electromagnets to alter brain function and found they could reduce the number of times healthy volunteers saw spontaneously experienced false perceptions.

The researchers altered the function of the temporal lobes with a method called transcranial magnetic stimulation or TMS while participants were asked to detect supposedly ‘hidden’ images in what were actually completely random dot patterns.

When compared to a control area at the top of the head, reducing left temporal lobe function significantly reduced the number of false perceptions.

During the procedure, participants were asked to look at a series of quickly presented dot patterns and told to indicate which had images ‘hidden’ within them.

Crucially, they were told not to guess and only to press a button when they genuinely detected a ‘hidden’ image. In actual fact, all the dot patterns were completely random and none contained ‘hidden’ images, so every ‘detect’ response was a false perception of meaningful information.

Just before each dot pattern was presented, the brain was stimulated with a pulse of TMS, either to the left or right temporal lobe, or a control spot at the top of the head known as the vertex.

TMS uses magnetic pulses to safely ‘switch off’ a small area of brain for a several hundred milliseconds.

When compared to the control area, temporarily ‘switching off’ an area on the left temporal lobe significantly reduced the number of false perceptions, suggesting that this brain area is likely to be involved in making meaningful connections, even when there’s no meaning to be found.

Seeing meaningful information in random data is known as ‘apophenia’ and statistically is known as a false positive or a Type I error.

Previous research has shown that this tendency is known to be enhanced in people who report high levels of paranormal experience, and to a greater extent, in people who experience psychosis – the mental state involving delusions and / or hallucinations that is most commonly linked to schizophrenia.

Other evidence suggests that differences in temporal lobe function are common in people diagnosed with schizophrenia.

The paper is published in the May edition of Cortex, but a pre-print is available at the link below if you don’t have access to the journal.

pdf of full-text paper.

Disclaimer: This study is from my own research group

Wiring the brain for synaesthesia

Neurophilosopher has a great article on a brain scanning study showing that people with synaesthesia have different patterns of brain connections compared to non-synaesthetes.

You read a lot of articles on the brain that use phrases like “wired differently”, suggesting that the connections in the brain are altered.

As the connections in our brain are changing all the time at the dendrite level, often this is just a meaningless way of saying “there’s a difference”.

Perhaps these sort of phrases are best applied to white matter which is the nearest you’ll find to genuine wires in the brain.

White matter fibres run in bundles, they carry electrical signals, and they are insulated by a fatty covering called myelin.

The connections of white matter have been quite hard to study in living people until the development of diffusion tensor imaging (DTI), a brain scanning technology that can specifically pick out the white matter fibres and create maps like the one in the picture.

Rarely when articles talk about “different brain wiring” do they actually mean detectable differences in white matter though.

In the DTI study covered by Neurophilosopher this is exactly what was studied, and it does indeed seem to be different in people who experience synaesthesia, a condition where some of the senses are crossed so, for example, numbers might be also experienced as colours.

DTI is a type of magnetic resonance imaging (fMRI) that measures the diffusion of water molecules. In the brain, water diffuses randomly, but tends to diffuse easier along the axons that are wrapped in myelin, the fatty protein that insulates nerve fibres. Diffusion tensor imaging can therefore be used to infer the size and direction of the bundles (or “fascicles”) of white matter tracts that connect different regions of the brain (above).

The Dutch researchers show that synaesthetes have more connections between the two adjacent areas in the fusiform gyrus than non-synaesthetes. They report their findings in the June issue of Nature Neuroscience.

As well as showing these differences between synaesthetes and non-synaesthetes, the authors also show that there are also differences in connectivity between synaesthetes who differ in the intensity of their sense-mixing experiences.

In other words, the researchers found people with synaesthesia had white matter ‘wiring’ between sensory areas that others don’t have, and that this wiring differed depending on how much synaesthesia the participants experience.

Just from the fantastically straight-forward explanation of DTI imaging given above, you can see that it’s a wonderfully written article.

Have a look at the full piece for more on this fascinating study.

Link to Neurophilospher on ‘Imaging of connectivity in the synaesthetic brain’.
Link to abstract of scientific study.

Neuroplastic fantastic

The New York Times has a review of a new book on how people have overcome brain damage through neuroplasticity – the brain’s ability to re-organise itself.

While this is nothing new, the brain has always had this ability, the discovery is relatively recent and rehabilitation is increasingly designed to take advantage of this process.

The book is called The Brain That Changes Itself and is apparently a series of case studies of how people’s lives have been improved by technology, psychotherapy or behavioural changes.

I suspect much of the excitement about neuroplasticity has been generated by the popularity of ‘cognitive fitness’ games, books and video games, all of which are based on the idea that you can ‘train your brain’ like a muscle.

While there is some truth in this, the effects are much less than many people might expect and certainly, most people don’t completely recover from brain injury.

I wonder if this book, like Peter Kramer’s 1994 book Listening to Prozac (ISBN 0140266712), will showcase the success stories, while most people’s experience will be much more modest.

There’s certainly nothing wrong with presenting the highlights of new and exciting therapies, but I wonder whether it raises some people’s expectations unrealistically.

Anyway, I’ve not read the book yet so I will have to see how it is tackled when I get a copy, and we’re certainly crying out for an accessible treatment of the subject.

Brain Damage, Brain Repair (ISBN 0198523378) is a great academic text, but it’s hardly something you’d take to the beach with you.

Link to NYT review.
Link The Brain That Changes Itself book / author’s website.

Memory exploratorium

San Francisco’s interactive science museum Exploratorium has a fantastic online memory exhibit, that includes articles, games, demonstrations and lectures from leading memory researchers.

The exhibit looks at the science of memory, as well as how it is used in art.

There’s a great article that explains memory distortions via Philip K. Dick and a try-it-yourself demonstration.

And for some unknown reason there’s a slideshow of a sheep brain dissection, when what would be genuinely informative would be to see the memory structures in the human brain.

It’s like going to an air show and watching someone take a bicycle apart.

Apart from that, the site’s fantastic. The lectures are particularly good. Most cover the science of memory, but one is on ideas of forgetting in myth and story.

Link to Exploratorium memory exhibit.

Finding the wily thief

A study that followed the lives of young males for 20 years has found that cognitive ability predicted whether the person was likely to engage in violence or theft if they had a tendency for antisocial behaviour.

Way back in ’79, the researchers recruited 698 males from 12 to 18 years of age from a random telephone survey in New Jersey. They kept in contact with them until the year 2000.

The researchers interviewed the participants and asked about any antisocial behaviour or offences.

They also tested the participants using neuropsychological tests of verbal IQ and executive function – the ability to co-ordinate mental resources that is closely linked to the frontal lobes.

In the males who did end up engaging in antisocial behaviour, the ones with cognitive difficulties tended to be violent, while the ones who were cognitively more able tended to steal.

In other words, low mental ability was associated with violence while the brighter individuals tended to engage in theft.

This could be because successful theft could require more thought, from planning a robbery to tricking another individual, whereas successful violence just requires a target.

One of the difficulties in interpreting these sorts of studies, is that they rely on participants admitting their own offences, so maybe more intelligent people are likely to describe their crimes differently.

However, it certainly wasn’t the case that more able people simply kept quiet about antisocial behaviour, as both reported wrongdoings, but of a different type.

UPDATE: Romeo Vitelli makes an interesting point in the comments:

All things being equal, theft is regarded as being less serious than violence is. Given that this study depends on self-report, are the ones who commit violence less likely to admit to committing violent crimes than the ones who commit theft?

Link to abstract of scientific paper.
Link to brief jargon-free summary.