Startling new psychological research challenges previous thinking that hair colour is merely about personal preference. Instead a massive consensus appears to exist on which hair colour is preferred, and there also appears to be such severe prejudice associated with the tint of your locks, this is possibly as harsh as racial discrimination.

For example, Nicolas Guéguen from the Université de Bretagne-Sud, in France, has just published a research paper entitled 'Hair Colour and Courtship: Blond Women Received More Courtship Solicitations and Redhead Men Received More Refusals', and it's published in the academic journal 'Psychological Studies'.

In the first study he conducted, female subjects, wearing blond, brown, black or red coloured wigs, were observed while sitting in a nightclub. In a second study, male collaborators wearing different coloured wigs asked women in a nightclub for a dance.

The intriguing results are that blond women were more frequently approached by men, whereas blond males did not receive more acceptances to their requests. However, in both conditions, red hair was associated with significantly less attractiveness.

Guéguen points out that previous surveys across the globe find dark fringes account for more than 90% of all natural hair, whereas blond accounts for only 2%, while red makes up only 1% worldwide. One theory had been that women who change their hair colour, prefer less common tints, so as to increase how they might stand out and therefore attract male attention.

Guéguen cites previous research into blond female door-to-door fundraisers receiving more donations, than their brunette counterparts. Another prior study found waitresses with blond hair got more tips. In yet another previous study, female confederates in their early twenties of the experimenter, were asked to hitchhike while wearing a blond, brown or black wig. Blond, compared to brown or black hair was associated with more male drivers stopping to offer rides, whereas no effect from hair color was found on female drivers who stopped.

In Guéguen's most recent research, a female subject sat in a night club for one hour, and the number of men who approached asking for a dance was measured. The experiment was carried out on 16 different nights in a four-week period. Each subject tested four different wigs four times. In that crucial hour, overall, 127 men approached the women wearing a blond wig, 84 men approached the brown wigged lady, 82 went up to the black haired woman but only 29 approached the red haired lady.

Guéguen reports previous research which found over 80% express a dislike for people with red hair, and also that the skin colour of most redheads was the most disliked of the eight skin colours proposed in a prior experiment.

Given that women are supposed to be less impressed with mere physical appearance, when evaluating how attracted they are to men, how would different hair colour fare on men when it came to women's desire in a similar night club scenario? In the second phase of the experiment, while slow songs were playing in the nightclubs, four 20 year old male confederates were instructed to ask a woman for a dance.

27.5% of the women said yes to men wearing a blond wig, 30% for the men with a brown wig, 35% acceptances for the invitation to dance were received for men wearing black hair, but only 13.8 % for men who donned a red wig.

Although psychologists argue that women are less interested in men's physical characteristics, when it comes to what determines attractiveness, (compared to men's preferences in women), it seems that red hair was associated in this experiment with dramatically less responsiveness to men's courtship requests from women.

Viren Swami and Seishin Barrett, psychologists at the University of Westminster, London, had earlier conducted a similar experiment. In their study the female subject, a natural brunette, dyed her hair blond and red. She sat in various nightclubs over many weeks, and the experimenters observed and counted how many men approached her during a one hour period. When she was blond, 60 men came up to her, while brunette the figure dropped to 42 and then when red, male interest languished at 18 approaches.

Swami and Barrett also surveyed men in these same nightclubs probing them on attitude to female hair colour, using pictures of the same female confederate with different hair colours. In the study entitled 'British men's hair color preferences: An assessment of courtship solicitation and stimulus ratings', when she was brunette the woman was actually rated as most attractive from her image, so how come the men actually approached her more, when she was blond?

One theory Swami and Barrett propose is based on the fact that their female confederate in the experiment was also rated as more 'needy' by men when she was a blond in the photographs, than when she was a brunette or redhead. The study has recently been published in the 'Scandinavian Journal of Psychology' and argues blonds being perceived as needier may have encouraged men to make approaches, possibly because it induced greater feelings of dominance or confidence in them, which in turn reduced their inhibition.

Perceptions of the blond confederate as being more needy may have reduced men's fear of rejection or fear of an hostile response, which increased their chances of approaching her as a blond.

Interestingly men rated the brunette in the pictures as most intelligent compared to all the hair colours, but also the most arrogant. The red head picture was rated as the least shy, the most temperamental and the most sexually promiscuous of all hair colours.

While settling the controversy over who is preferred in the bedroom might have to await more research, there is some intriguing psychological research which finds a preference for red heads in the board room.

Margaret Takeda, Marilyn Helms and Natalia Romanova from the University of Tennessee and Dalton State College in the USA recently looked at the hair colour of all 500 Chief Executive Officers of the London Financial Times Stock Exchange (FTSE) top 500 companies by market capitalization.

Of the 500 CEOs analyzed, 5% were blonds and 4% had red hair, but given that within the UK population, approximately 25% boast blond and 1% red hair, the researchers found blonds, who are perceived traditionally as incompetent but likeable, were under-represented in positions of corporate leadership in the UK. Redheads, while normally a minute number in the U.K. population, were 'over-selected' to run some of the UKs (and Europe's) leading, richest companies.

Stereotypically this would be expected, the authors of this study entitled 'Hair Colour Stereotyping and CEO Selection in the United Kingdom', argue, as redheads are perceived to be competent, though not especially congenial.

Takeda and colleagues pose an interesting question in their paper published in 2006 in the academic periodical, 'Journal of Human Behaviour in the Social Environment' - should hair colour be included in the anti-discrimination legislation? They point out if selection of CEOs is partly based on hair colour, as their research indicates, does it constitute discriminatory prejudice?

The authors note that in the US, for example, colour as currently defined in the statutory basis for non-discrimination in employment, refers to the shade of a person's skin, and not race alone. This is because within a race, a variety of skin colours can exist. There is well-documented bias in faviour of lighter skin so US discrimination laws refer to skin colour, but, in the light of recent research, should they now also include hair colour?

Incidentally while discussing discrimination, it might be important to note that in the Takeda study, only two of the 500 CEOs were women.