Inside the mind of an adulterer

Christine Hemming is "not best pleased" by the discovery that her husband, the Liberal Democrat MP John Hemming, is to become a father again - his assistant, Emily Cox is due in October. The revelation that her husband has been conducting a six-year-affair with the 27-year-old Cox barely ruffled Ms Hemmings, who has announced that this mistress is "about number 26" in a series of affairs, and vowed to stand by her man.

To most other people, the sheer number of infidelities may well have come as a shock - even to those who felt no more surprise was at all possible over a politician's behaviour. But, in fact, the scale of his adultery may echo the recent findings of various psychologists.

Although infidelity remains the main reason cited when petitioning for a divorce, surprisingly little advance has been made by psychologists investigating the predicament. Not surprisingly, those who are unfaithful tend to be cautious about discussing their private affairs, and, unlike those suffering from more obvious psychological problems, adulterers rarely think there is anything "wrong" with them.

Now, the new science of extramarital affairs has begun to produce some surprising findings. Psychologists Vincent Egan and Sarah Angus of Glasgow Caledonian University recently published a relatively unique study into the mind of the adulterer which focused on the personalities of those who admitted to infidelity, as opposed to those who expressed a strong desire for it, as is more usual. While the number of men and women who committed adultery was not significantly different (in their sample roughly twice as many women as men admitted to it), they found that men were more likely to have extra-marital sex many more times than women.

One reason for this, they argue, is that women are fussier than men when it comes to who they will choose to have an affair with. Joanna Scheib, a psychologist at the University of California, recently looked into this phenomenon. She found that women would be much more likely to seek out an illicit affair with a man with striking good looks than a man would. What was particularly intriguing was that these women were much more concerned about 'good character' when it came to looking for a long term mate. Scheib speculated that, for women, "extra-pair mateships" serve an unconscious or evolutionary function of obtaining "good genes."

The evolutionary psychology theory here is that women look for a man with which to produce a good-looking son - who himself is more likely to pass on her genes - while also seeking a good character partner to stay with her and help her look after the son. Egan and Angus, the Glasgow psychologists, found female adulterers were not significantly less manipulative and deceitful than the male. Instead, they argue that, irrespective of sex, the skills needed to carry out infidelity require a willingness to betray another person.

But does that mean adulterers are actually psychologically dysfunctional? Is something wrong with them? And should 'treatment' be offered for adulterers? Psychologists had speculated that perhaps the preference for a series of short-term mates was due to an insecure childhood. Perhaps, it was thought, unresponsive, abusive or inconsistent care-giving produced children who developed a negative sense of themselves and were uncomfortable with true intimacy.

But now a new theory is gaining ground. Perhaps it's the other way round? Maybe it's those with high self-esteem who sleep around - simply because they can and it makes sense from a genetic standpoint. David Schmitt, a psychologist at Bradley University in Illinois, is one of the prime advocates of this thesis. He points out that the headlines tend to be dominated (as they have been over the last few days) by men of "high mate value" (ie high status and self-esteem) who engage in promiscuous and unfaithful mating strategies. This, he argues, has clear reproductive advantages.

Schmitt suggests that the way to test whether adultery is the product of a superior mind is to see whether maladaptive personality traits linked to insecure attachment cluster among those who prefer 'short-term mating strategies'. Schmitt found that men who commit adultery tend to score much higher on self-esteem and social confidence than monogamous men. The preference for short-term mating in women occurred where more insecure personality traits were found, suggesting that, for women, extra-marital affairs might suggest "something wrong".

Schmitt has conceded that both men and women who preferred more and shorter relationships tended to trust others less. He argues, however, that if these adulterers were brought up in the kind of family environments which were unstable it would make sense to assume that you may become an adult who preferred not to trust.

However, Schmitt is just one of a number of psychologists furthering new theories about adultery. Dr Gillian Rhodes, who lead a team of psychologists at the University of Western Australia, found recently that the more facially attractive a man is the more short term partners he has, while the more facially attractive a woman is the more long term partners she has.

This provides an interesting scientific confirmation of the widespread belief amongst women of their reluctance to consider an extremely good-looking man for a long term relationship because of their fear he will be unfaithful or unable to commit. Men, in contrast, are just very grateful to land a beautiful woman without considering the downsides. It would seem science is proving that that particular female intuition is completely justified.

Dr Raj Persaud is Consultant Psychiatrist at the Maudsley Hospital in south London and Gresham Professor for Public Understanding of Psychiatry