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17 September 2014
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Reading Faces: Facial Prejudice

Read my face

If you visit the movies much, you'll know just how full of stereotypes they are. Heroines in romantic comedies are invariably sweet-faced and girly. Male action heroes are invariably square-jawed and beetle-browed.

Russell Crowe
What personality traits do we associate with masculine faces?

For instance, would hard man Russell Crowe have been quite as convincing hacking his way through an arena in the film Gladiator had he been born baby-faced and weak-chinned? Professor David Perrett of the University of St Andrews thinks not. Perrett is investigating how the features of a person's face shape how we think of them.

His technique of digitally manipulating faces first attracted attention four years ago, when he showed that women prefer more masculine faces during the fertile period of their menstrual cycle. Faces were made more masculine by strengthening the jawline and brows and more feminine by widening the face and raising the eyebrows.

Perrett's team has found that one of the most important things that influences perceived personality is the set of features that give a face its gender. This seems to have its roots in the different personality traits we associate with men and women.

The Big Five

To test his hypotheses, Perrett is using the most widely accepted framework of human personality: the five-factor model. This consists of:

  • Extraversion - affectionate, talkative, sociable
  • Conscientiousness - careful, hard-working, conscientious
  • Agreeableness - forgiving, sympathetic, warm
  • Openness to experience - creative, original, independent
  • Neuroticism - nervous, worrying, highly strung
Computer lab at Stirling University
Volunteers rate face composites in a university computer laboratory.

With this information, they created average extravert and average introvert faces from the same 15 images by using computer software to amplify some features and suppress others. These composite images were then used to transform other faces, making them either more introvert or more extravert.

"A lot of the things that we're seeing in extravert and introvert faces are transient things like how likely you are to smile," says Dr Tony Little, of the Perception Lab at St Andrews. Indeed, while the withdrawn look of introvert faces is instantly recognisable, extravert faces seem to be fixed in the earliest stages of a grin.

Fight club

But why would such subtle facial cues have evolved? Dr Little believes they might have played an important role in physical confrontations between our ancient ancestors.

"We all become highly competitive when confronting an opponent we think we can realistically beat. However, we will submit to opponents we feel are superior to us in order to avoid fighting a battle we will probably lose. Evolution is a game of survival, so it pays to know when to fight and when to run.

Female eyes
The eyes have it. Do we really associate feminine features with kindness?

Agreeableness is the personality dimension most important for social success. People who fall towards the positive pole of agreeableness are sympathetic, helpful and trusting. Those who fall towards the negative pole are uncooperative, suspicious and cynical. Perrett has found a strong link between agreeableness and femininity.

"People find feminine faces, whether male or female, more agreeable. This appears to be because women are perceived as kind and soft-hearted," says Perrett. "Faces seem less agreeable to people as you make them more masculine," he adds.

Therefore, men with slightly feminine facial features should be perceived as more agreeable than their macho counterparts. And women with 'cute' feminine looks should be seen as more agreeable than women with more masculine features.

These assumptions might be transmitted culturally. But Perrett is working on the hunch that they are in fact instinctive reactions that have developed over the course of evolution.

In the evolutionary past, our ability to recognise clues about someone's personality in their face may have helped us decide how to deal with them effectively. In conflict, it may also have helped us know who we had a good chance of beating and who might prove a tough opponent.

But the fact that a face's gender, rather than more transient features such as facial expressions, has such a strong influence on the personality we ascribe to a face suggests that personality must have some biological basis.

Boys will be boys

Our perceptions of agreeableness exactly mirror the action of the male sex hormone testosterone. Several studies have shown that testosterone tends to make men more confrontational and anti-social.

A male jawline
Testosterone is responsible for masculinizing the face, but it also has well-known effects on behaviour.

Professor Dan Olweus and his team at the University of Berggen in Norway tested the effect of testosterone on the behaviour of a group of teenage boys. They found that contrary to predictions, high levels of testosterone were not associated with overt aggression in teenage boys.

But the boys with the highest testosterone were more irritable and disagreeable. They also displayed an aggressive response to provocation, being more likely to answer back to a teacher that criticised them.

Professor Allan Booth and Dr James Dabbs of Penn State University have even shown that, in a group of US air force servicemen, males with testosterone levels significantly above the average were 50% less likely to marry, which may suggest they have difficulty co-operating in a partnership with another individual. Testosterone is also responsible for giving a face its masculine qualities.

Men behaving badly

But this shouldn't be viewed as an excuse for grouchiness or bad behaviour. Testosterone only seems to have this effect in the proportion of the population whose brains are predisposed to such behaviour.

There seems to be an equally important proportion of high-testosterone individuals who do not try to dominate through anti-social behaviour. This sort of behaviour would seem to cause downward mobility in the class system. But studies have found no evidence for a concentration of high-testosterone males amongst socioeconomic groups with low incomes. Instead, they are evenly spread across society.

Masculinity and femininity also seems to affect another well-studied personality trait: extraversion. But in this case, there seems to be a parallel rather than opposite relationship between the action of male and female sex hormones.

Professor Werner Martin Herrmann of the Free University in Berlin found that administering oestrogen to female volunteers made them score more highly for extraversion on personality questionnaires. Several other studies have shown that testosterone is responsible for making makes men more extravert, encouraging them to try and dominate social situations.

That little bit extra

Perrett has found preliminary evidence that masculine male faces are perceived as more extravert than their female counterparts. And feminine female faces are seen as more extravert than more butch faces. Again, this trend exactly mirrors the effect of sex hormones.

Do feminine female faces seem more extravert?

The biological basis of neuroticism is not as clear. It does not seem to be directly affected by the action of sex hormones. But, on average, women score more highly for neuroticism on personality questionnaires, so Perrett believes that faces might start to look more neurotic as you increase their femininity.

First impressions count

It is not known how openness and conscientiousness will be affected by changing the masculinity or femininity of a face. However, masculine faces are often described as untrustworthy, which may have implications for the types of faces we regard as conscientious, or reliable.

They say we shouldn't judge a book by its cover. Even though we should know better, every day we use those old tricks we learnt in our evolutionary past. Our distant ancestors, it seems, knew what every seasoned businessman knows today: that first impressions count.

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