Why do we bite our nails?

It can ruin the appearance of your hands, could be unhygienic and can hurt if you take it too far. So why do people do it? Biter Tom Stafford investigates

What do ex-British prime minster Gordon Brown, Jackie Onassis, Britney Spears and I all have in common? We all are (or were) nail biters.

It’s not a habit I’m proud of. It’s pretty disgusting for other people to watch, ruins the appearance of my hands, is probably unhygienic and sometimes hurts if I take it too far. I’ve tried to quit many times, but have never managed to keep it up.

Lately I’ve been wondering what makes someone an inveterate nail-biter like me. Are we weaker willed? More neurotic? Hungrier? Perhaps, somewhere in the annals of psychological research there could be an answer to my question, and maybe even hints about how to cure myself of this unsavoury habit.

My first dip into the literature shows up the medical name for excessive nail biting: ‘onychophagia’. Psychiatrists classify it as an impulse control problem, alongside things like obsessive compulsive disorder. But this is for extreme cases, where psychiatric help is beneficial, as with other excessive grooming habits like skin picking or hair pulling. I’m not at that stage, falling instead among the majority of nail biters who carry on the habit without serious side effects. Up to 45% of teenagers bite their nails, for example; teenagers may be a handful but you wouldn’t argue that nearly half of them need medical intervention. I want to understand the ‘subclinical’ side of the phenomenon – nail biting that isn’t a major problem, but still enough of an issue for me to want to be rid of it.

It’s mother’s fault

Psychotherapists have had some theories about nail biting, of course. Sigmund Freud blamed it on arrested psycho-sexual development, at the oral stage (of course). Typical to Freudian theories, oral fixation is linked to myriad causes, such as under-feeding or over-feeding, breast-feeding too long, or problematic relationship with your mother. It also has a grab-bag of resulting symptoms: nail biting, of course, but also a sarcastic personality, smoking, alcoholism and love of oral sex. Other therapists have suggested nail-biting may be due to inward hostility – it is a form of self-mutilation after all – or nervous anxiety.

Like most psychodynamic theories these explanations could be true, but there’s no particular reason to believe they should be true. Most importantly for me, they don’t have any strong suggestions on how to cure myself of the habit. I’ve kind of missed the boat as far as extent of breast-feeding goes, and I bite my nails even when I’m at my most relaxed, so there doesn’t seem to be an easy fix there either. Needless to say, there’s no evidence that treatments based on these theories have any special success.

Unfortunately, after these speculations, the trail goes cold. A search of a scientific literature reveals only a handful of studies on treatment of nail-biting. One reports that any treatment which made people more aware of the habit seemed to help, but beyond that there is little evidence to report on the habit. Indeed, several of the few articles on nail-biting open by commenting on the surprising lack of literature on the topic.

Creature of habit

Given this lack of prior scientific treatment, I feel free to speculate for myself. So, here is my theory on why people bite their nails, and how to treat it.

Let’s call it the ‘anti-theory’ theory. I propose that there is no special cause of nail biting – not breastfeeding, chronic anxiety or a lack of motherly love. The advantage of this move is that we don’t need to find a particular connection between me, Gordon, Jackie and Britney. Rather, I suggest, nail biting is just the result of a number of factors which – due to random variation – combine in some people to create a bad habit.

First off, there is the fact that putting your fingers in your mouth is an easy thing to do. It is one of the basic functions for feeding and grooming, and so it is controlled by some pretty fundamental brain circuitry, meaning it can quickly develop into an automatic reaction. Added to this, there is a ‘tidying up’ element to nail biting – keeping them short – which means in the short term at least it can be pleasurable, even if the bigger picture is that you end up tearing your fingers to shreds. This reward element, combined with the ease with which the behaviour can be carried out, means that it is easy for a habit to develop; apart from touching yourself in the genitals it is hard to think of a more immediate way to give yourself a small moment of pleasure, and biting your nails has the advantage of being OK at school. Once established, the habit can become routine – there are many situations in everyone’s daily life where you have both your hands and your mouth available to use.

Understanding nail-biting as a habit has a bleak message for a cure, unfortunately, since we know how hard bad habits can be to break. Most people, at least once per day, will lose concentration on not biting their nails.

Nail-biting, in my view, isn’t some revealing personality characteristic, nor a maladaptive echo of some useful evolutionary behaviour. It is the product of the shape of our bodies, how hand-to-mouth behaviour is built into (and rewarded in) our brains and the psychology of habit.

And, yes, I did bite my nails while writing this column. Sometimes even a good theory doesn’t help.

 

This was my BBC Future column from last week

It’s your own time you’re wasting

CC Licensed photo by Flickr user alamosbasement. Click for source.British teachers have voted to receive training in neuroscience ‘to improve classroom practice’ according to a report in the Times Educational Supplement and the debate sounded like a full-on serial head-desker.

The idea of asking for neuroscience training at all sounds a little curious but the intro seemed like it could be quite reasonable:

Members of the Association of Teachers and Lecturers (ATL) at the union’s annual conference narrowly voted for a motion calling for training materials and policies on applying neuroscience to education and for further research on how technology can be used to develop better teaching.

Now, this could be just a request to be kept up-to-date with the latest educational neuroscience developments. Sounds fascinating but probably not that practically useful as neuroscience doesn’t really have much to offer your average classroom teacher.

Enter Julia Neal, a member of the council for the union’s leadership division and leading member of the head-desk working group:

“It is true that the emerging world of neuroscience presents opportunities as well as challenges for education, and it’s important that we bridge the gulf between educators, psychologists and neuroscientists.”

Neuroscience could also help teachers tailor their lessons for creative “right brain thinkers”, who tend to struggle with conventional lessons but often have more advanced entrepreneurial skills, Ms Neal said.

Entrepreneurial skills being a well known function of the ‘right brain’. It’s why Bill Gates always veers slightly to the left when he walks. So why this sudden interest in neuroscience in the classroom I wonder?

Earlier this year, the government-backed Education Endowment Foundation and the Wellcome Trust launched a £6 million scheme that will fund neuroscientific research into learning.

Kerching! But the best bit of the debate is where a neuropsychologist stands up and goes ‘well, I don’t think it’s as simple as you’re making out’:

However Joanne Fludder, a classroom teacher in Reading with a doctorate in neuropsychology, opposed the motion.

She told the conference that the field was “very complicated” and theories were “still in flux” as research was carried out.

Boo! Get her off!
 

Link to article in the Times Educational Supplement

Does the unconscious know when you’re being lied to?

The headlines
BBC: Truth or lie – trust your instinct, says research

British Psychological Society: Our subconscious mind may detect liars

Daily Mail: Why you SHOULD go with your gut: Instinct is better at detecting lies than our conscious mind

The Story
Researchers at the University of California, Berkeley, have shown that we have the ability to unconsciously detect lies, even when we’re not able to explicitly say who is lying and who is telling the truth.

What they actually did
The team, led by Leanne ten Brinke of the Haas School of Business, created a set of videos using a “mock high-stakes crime scenario”. This involved asking 12 volunteers to be filmed while being interrogated about whether they had taken US$100 dollars from the testing room. Half the volunteers had been asked to take the $100, and had been told they could keep it if they persuaded the experimenter that they hadn’t. In this way the researchers generated videos of both sincere denials and people who were trying hard to deceive.

They then showed these videos to experimental participants who had to judge if the people in the videos were lying or telling the truth. As well as this measure of conscious lie detection, the participants also completed a task designed to measure their automatic feelings towards the people in the videos.

In experiment one this was a so-called Implicit Association Test which works by comparing the ease with which the participants associated the faces of the people in the videos with the words TRUTH or LIE. Experiment two was a priming test, where the faces of the people in the videos changed the speed at which people then made judgements about words they were then given related to truth-telling and deception.

The results of the study showed that people were no better than chance in their explicit judgements of who was telling the truth and who was lying, but the measurements of their other behaviours showed significant differences. Specifically, for people who were actually lying, observers were slower to associate their faces with the word TRUTH or quicker to associate it with the word LIE. The second experiment showed that after seeing someone who was actually telling the truth people made faster judgements about words related to truth-telling and slower judgements about words related to deception (and vice versa after a video of someone who was actually lying).

How plausible is this?
The result that people aren’t good at detecting lies is very well established. Even professionals, such as police officers, perform poorly when formally tested on their ability to discriminate lying from truth telling.

It’s also very plausible that the way in which you measure someone’s judgement can reveal different things. For example, people are in general notoriously bad at reasoning about risk when they are asked to give estimates verbally, but measurements of behaviour show that we are able to make very accurate estimates of risk in the right circumstances.

It fits with other results in psychological research which show that over thinking certain judgements can reduce their accuracy

Tom’s take
The researchers are trying to have it both ways. The surprise of the result rests on the fact that people don’t score well when asked to make a simple truth vs lie judgement, but their behavioural measures suggest people would be able to make this judgement if asked differently. Claiming the unconscious mind knows what the conscious mind doesn’t is going too far – it could be that the simple truth vs lie judgement isn’t sensitive enough, or is subject to some bias (participants afraid of being wrong for example).

Alternatively, it could be that the researchers’ measures of the unconscious are only sensitive to one aspect of the unconscious – and it happens to be an aspect that can distinguish lies from an honest report. How much can we infer from the unconscious mind as a whole from the behavioural measures?

When reports of this study say “trust your instincts” they ignore the fact that the participants in this study did have the opportunity to trust their instincts – they made a judgement of whether individuals were lying or not, presumably following the combination of all the instincts they had, including those that produced the unconscious measures the researchers tested. Despite this, they couldn’t guess correctly if someone was lying or not.

If the unconscious is anything it will be made up of all the automatic processes that run under the surface of our conscious minds. For any particular judgement – in this case detecting truth telling – some process may be accurate at above chance levels, but that doesn’t mean the unconscious mind as a whole knows who is lying or not.

It doesn’t even mean there is such as thing as the unconscious mind, just that there are aspects to what we think that aren’t reported by people if you ask them directly. We can’t say that people “knew” who was lying, when the evidence shows that they didn’t or couldn’t use this information to make correct judgements.

Read more
The original paper: Some evidence for unconscious lie detection”

The data and stimuli for this experiment are freely available – a wonderful example of “open science.”

A short piece I wrote about how articulating your feelings can get in the way of realising them.

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Ghost psychiatry

The Australian Journal of Parapsychology has an article about post-traumatic stress disorder in people who have been murdered.

I suspect diagnosing mental disorder in those who have passed onto another plane of existence isn’t the easiest form of mental health assessment but it seems this gentleman is determined to give it a go.

Psychological phenomena in dead people: Post- traumatic stress disorder in murdered people and its consequences to public health

Australian Journal of Parapsychology, Volume 13 Issue 1 (Jun 2013)

Wasney de Almeida Ferreira

The aims of this paper are to narrate and analyze some psychological phenomena that I have perceived in dead people, including evidence of post-traumatic stress disorder (PTSD) in murdered people. The methodology adopted was “projection of consciousness” (i.e., a non-ordinary state of consciousness), which allowed me to observe, interact, and interview dead people directly as a social psychologist. This investigation was based on Cartesian skepticism, which allowed me a more critical analysis of my experiences during projection of consciousness. There is strong evidence that a dead person: (i) continues living, thinking, behaving after death as if he/she still has his/her body because consciousness continues in an embodied state as ‘postmortem embodied experiences’; (ii) may not realize for a considerable time that he/she is already dead since consciousness continues to be embodied after death (i.e., ‘postmortem perturbation’ – the duration of this perturbation can vary from person to person, in principle according to the type of death, and the level of conformation), and (iii) does not like to talk, remember, and/or explain things related to his/her own death because there is evidence that many events related to death are repressed in his/her unconscious (‘postmortem cognitive repression’). In addition, there is evidence that dying can be very traumatic to consciousness, especially to the murdered, and PTSD may even develop.

It is worth noting that the concept of post-mortem PTSD was largely invented by Big Parlour as a way of selling seances, when what spirits really need is someone to help them understand their experiences.
 

Link to abstract for article (via @WiringTheBrain)

Do violent video games make teens ‘eat and cheat’ more?

By Tom Stafford, University of Sheffield

The Headlines

Business Standard: Violent video games make teens eat more, cheat more

Scienceblog.com: Teens ‘Eat more, cheat more’ after playing violent video games

The Times of India: Violent video games make teens cheat more

The story

Playing the violent video game Grand Theft Auto made teenagers more aggressive, more dishonest and lowered their self control.

What they actually did

172 Italian high school students (age 13-19 years old), about half male and half female, took part in an experiment in which they first played a video game for 35 minutes. Half played a non-violent pinball or golf game, and half played one of the ultra-violent Grand Theft Auto games.

During the game they had the opportunity to eat M&M’s freely from a bowl (the amount they scoffed provided a measure of self-control), and after the game they had the opportunity take a quiz to earn raffle tickets (and the opportunity to cheat on the quiz, which provided a measure of dishonesty). They also played a game during which they could deliver unpleasant noises to a fellow player as punishments (which was used to measure of aggression).

Analysis of the results showed that those who played the violent video game had lower scores when it came to the self-control measure, cheated more and were more aggressive. What’s more, these effects were most pronounced for those who had high scores on a scale of “moral disengagement” – which measures how loose your moral thinking is. In other words, if you don’t think too hard about right and wrong, you score highly.

How plausible is this?

This is a well designed study, which uses random allocation to the two groups to try to properly assess causation (does the violent video game cause immoral behaviour?).

The choice of control condition was reasonable (the other video games were tested and found to be just as enjoyed by the participants), and the measures are all reasonable proxies for the things we are interested in. Obviously you can’t tell if weakened self-control for eating chocolate will mean weakened self-control for more important behaviour, but it’s a nice specific measure which is practical in an experiment and which just might connect to the wider concept.

The number of participants is also large enough that we can give the researchers credit for putting in the effort. Getting about 85 people in each group should give a minimum of statistical power, which means any effects might be reliable.

As an experimental psychologist, there’s lots for me to like about this study. The only obvious potential problem that I can see is that of demand effects, subtle cues that can make participants aware of what the experimenter expects to find or how they should behave. The participants were told they were in a study which looked at the effects of video games, so it isn’t impossible that some element of their behaviour was playing up to what they reasonably guessed the researchers were looking for and it doesn’t look like the researchers checked if this might be the case.

Tom’s take

You can’t leap to conclusions from a single study, of course – even a well designed one. We should bear in mind the history of moral panics around new technology and media. Today we’re concerned with violent video games, 50 years ago it was comic books and jazz. At least jazz is no longer corrupting young people.

Is our worry about violent video games just another page in the history of adults worrying about what young people are up to? That’s certainly a factor, but unlike jazz, it does seem psychologically plausible that a game where you enjoy reckless killing and larceny might encourage players to be self-indulgent and nasty.

Reviews suggest violent media may be a risk factor for violent behaviour, just like cigarette smoke is a risk factor for cancer. Most people who play video games won’t commit violent acts, just like most people who passive smoke won’t get cancer.

The problem is other research reviews into impact of violent entertainment on our behaviour suggest the evidence for a negative effect is weak and contradictory.

Video games are a specific example of the general topic of if and how media affect our behaviour. Obviously, we are more than complete zombies, helpless to resist every suggestion or example, but we’re also less than completely independent creatures, immune to the influence of other people and all forms of entertainment. Where the balance lies between these extremes is controversial.

For now, I’m going to keep an open mind, but as a personal choice I’m probably not going to get the kids GTA for Christmas.

Read more

The original paper: Interactive Effect of Moral Disengagement and Violent Video Games on Self-Control, Cheating, and Aggression

@PeteEtchells provides a good summary of the scientific (lack of) consensus: What is the link between violent video games and aggression?

Commentary by one researcher on the problems in the field of video game research: The Challenges of Accurate Reporting on Video Game Research

And a contrary research report: A decade long study of over 11,000 children finds no negative impact of video games

Tom Stafford does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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Are classical music competitions judged on looks?

Looking at the evidence behind a recent news story

The headlines

The Los Angeles Times: People trust eyes – not ears – when judging musicians

Classic FM: Classical singers judged by actions not voice

Nature: Musicians’ appearances matter more than their sound

The story

If you wanted to pick out the musician who won a prestigious classical music competition would you listen to a clip of them playing or watch a silent video of them performing the same piece of music?

Most of us would go for an audio clip rather than video, and we’d be wrong. In a series of experiments, Chia-Jung Tsay from University College London, showed that both novices and expert musicians were better able to pick out the winners when they watched rather than listened to them.

The moral, we’re told, is that how you look is more important than how you sound, even in elite classical music competitions.

What they actually did

Dr Tsay, herself a classically trained musician, used footage from real international classical music competitions. She took the top three finalists and asked volunteers to pick out the real winner – with a cash incentive – by looking at video without sound, sound without video, or both.

Over a series of experiments she showed that people think that audio will be more informative than video, but actually people are able to pick the real winner when watching video clips. But they aren’t able to do this when listening to audio clips (these test subjects only perform at the level of chance). The shocking thing is that when people get sound and video clips, which notionally contain more information, they still perform at chance. The implication being that they would do better if they could block their ears and ignore the sound.

Follow up experiments suggested that people’s ability to pick winners depended on their being able to pick out things associated with “stage presence”. A video reduced to line drawings, designed to remove details and emphasise motion, still allowed people to pick out winners at an above chance rate. Another experiment showed that asking people to identify the “most confident, creative, involved, motivated, passionate, and unique performer” tallied with the real winners.

How plausible is this?

We’re a visual species. How things look really matters, as everyone who has dressed up for an interview knows. It’s also not uncommon for us to be misled into believing that how something looks isn’t as important as it really is (here’s an example: judging wine by the labels rather than the taste).

What is less plausible is the spin put on the story by the headlines. We all know that looks are important, but how can they really be more important than sound in a classical music competition? The most important thing really is the sound, but this research resonates with a popular cliché about how irrational we are.

Tom’s take

The secret to why these experiments give the results they do is in this detail: the judgement that people were asked to make was between the top three finalists in prestigious international competitions. In other words, each of these musicians is among the best in the world at what they do. The best of the best even.

In all probability there is a minute difference between their performances on any scale of quality. The paper itself admits that the judges themselves often disagree about who the winner is in these competitions.

The experimental participants were not scored according to some abstract ability to measure playing quality, but according to how well they were able to match real-world competition outcome.

The experiments show that matching the judges in these competitions can be done based on sight but not on sound. This isn’t because sight reveals playing quality, but because sight gives the experimental participants similar biases to the real judges. The real expert judges are biased by how the performers look – and why not, since there is probably so little to choose between them in terms of how they sound?

This is why the conclusion, spelt out in the original paper, is profoundly misleading: “The findings demonstrate that people actually depend primarily on visual information when making judgements about music performance”. It remains completely plausible that most of us, most of the time, judge music on how it sounds, just like we assumed before this research came out.

In ambiguous cases we might rely on looks over sounds – even the experts among us. This is a blow to musicians who thought it was always just about sound – but isn’t a revelation to the rest of us who knew that when choices are hard, whether during the job interview or the music competition, looks matter.

Read more

The original paper: Sight over sound in the judgment of music performance. Tsay, C-J (2013), Proceedings of the National Academy of Sciences

Special mention for the BBC and reporter Melissa Hogenboom who were the only people, as far as I know, who managed to report this story with an accurate headline: Sight dominates sound in music competition judging

The interaction between the senses is an active and fascinating research area. Read more from the Crossmodal Research Laboratory at the Univeristy of Oxford and Cross-modal perception of music network at the University of Sheffield

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What makes the ouija board move

The mystery isn’t a connection to the spirit world, but why we can make movements and yet not realise that we’re making them.

Ouija board cups and dowsing wands – just two examples of mystical items that seem to move of their own accord, when they are really being moved by the people holding them. The only mystery is not one of a connection to the spirit world, but of why we can make movements and yet not realise that we’re making them.

The phenomenon is called the ideomotor effect and you can witness it yourself if you hang a small weight like a button or a ring from a string (ideally more than a foot long). Hold the end of the string with your arm out in front of you, so the weight hangs down freely. Try to hold your arm completely still. The weight will start to swing clockwise or anticlockwise in small circles. Do not start this motion yourself. Instead, just ask yourself a question – any question – and say that the weight will swing clockwise to answer “Yes” and anticlockwise for “No”. Hold this thought in mind, and soon, even though you are trying not to make any motion, the weight will start to swing in answer to your question.

Magic? Only the ordinary everyday magic of consciousness. There’s no supernatural force at work, just tiny movements you are making without realising. The string allows these movements to be exaggerated, the inertia of the weight allows them to be conserved and built on until they form a regular swinging motion. The effect is known as Chevreul’s Pendulum, after the 19th Century French scientist who investigated it.

What is happening with Chevreul’s Pendulum is that you are witnessing a movement (of the weight) without “owning” that movement as being caused by you. The same basic phenomenon underlies dowsing – where small movements of the hands cause the dowsing wand to swing wildly – or the Ouija board, where multiple people hold a cup and it seems to move of its own accord to answer questions by spelling out letters. The effect also underlies the sad case of “facilitated communication“, a fad whereby carers believed they could help severely disabled children communicate by guiding their fingers around a keyboard. Research showed that the carers – completely innocently – were typing the messages themselves, rather than interpreting movements from their charges.

The interesting thing about the phenomenon is what it says about the mind. That we can make movements that we don’t realise we’re making suggests that we shouldn’t be so confident in our other judgements about what movements we think are ours. Sure enough, in the right circumstances, you can get people to believe they have caused things that actually come from a completely independent source (something which shouldn’t surprise anyone who has reflected on the madness of people who claim that it only started raining because they forget an umbrella).

You can read what this means for the nature of our minds in The Illusion of Conscious Will by psychologist Daniel Wegner, who sadly died last month. Wegner argued that our normal sense of owning an action is an illusion, or – if you will – a construction. The mental processes which directly control our movements are not connected to the same processes which figure out what caused what, he claimed. The situation is not that of a mental command-and-control structure like a disciplined army; whereby a general issues orders to the troops, they carry out the order and the general gets back a report saying “Sir! We did it. The right hand is moving into action!”. The situation is more akin to an organised collective, claims Wegner: the general can issue orders, and watch what happens, but he’s never sure exactly what caused what. Instead, just like with other people, our consciousness (the general in this metaphor) has to apply some principles to figure out when a movement is one we’ve made.

One of these principles is that cause has to be consistent with effect. If you think “I’ll move my hand” and your hand moves, you’re likely to automatically get the feeling that the movement was one you made. The principle is broken when the thought is different from the effect, such as with Chevreul’s Pendulum. If you think “I’m not moving my hand”, you are less inclined to connect any small movements you make with such large visual effects. This maybe explains why kids can shout “It wasn’t me!” after breaking something in plain sight. They thought to themselves “I’ll just give this a little push”, and when it falls off the table and breaks it doesn’t feel like something they did.

This is my column for BBC Future from a few weeks back. The original is here. It’s a Dan Wegner tribute column really – Rest in Peace, Dan