A particular liking for bitter-tasting foods and drinks such as coffee and tonic water could mean you have psychopathic tendencies.

Psychologists have found that those with a preference for bitter tastes were more likely to exhibit signs of Machiavellianism, sadism, and narcissism.

That is, they were more prone to being duplicitous and self-serving, cold-hearted and lacking in empathy, vain and selfish, and more likely to derive pleasure from other people's pain.

Psychologists have found that people with a preference for bitter foods and drinks, such as coffee and tonic water, were more likely to exhibit signs of Machiavellianism, sadism, and narcissism. This means they are more prone to being duplicitous and self-serving, cold-hearted and lacking in empathy, vain and selfish

The findings of the study provide the 'first empirical evidence that bitter taste preferences are linked to malevolent personality traits,' said the researchers from Innsbruck University in Austria, who studied 1,000 people in two separate experiments.

'The results suggest that how much people like bitter-tasting foods and drinks is stably tied to how dark their personality is.'

Bitter foods include unsweetened cocoa, black coffee, radishes and the quinine in tonic water.

For the first experiment, 500 men and women were shown a long list of foods with equal numbers of sweet, salty, sour and bitter foods. These included chocolate cake, bacon, vinegar and radishes.

PSYCOPATHS HAVE WIDER HEADS Having a wider face has been linked with higher levels of attraction and aggression, and recent research suggested it may also be a sign of psychopathy. A study of students and prison inmates found that men with a higher facial width-to-height ratio were more likely to exhibit what's known as 'self-centred impulsivity'. They also showed signs of 'fearless dominance' as well as a tendency to blame other people for problems. Self-centred impulsivity is a category of traits including Machiavellian egocentricity and is the tendency to consider only personal needs, with a disregard for the interests of anyone else. Those high in self-centred impulsivity also tend to neglect the social norms and regulations that the rest of us live by. Fearless dominance, meanwhile, includes a tendency to embrace risk without any fear, showing limited reaction to awful events that would make the rest of us panic - combined with a tendency to appear charming and influential. Advertisement

They were asked to rate how much they liked each of them on a six-point scale ranging from dislike strongly to like strongly.

The participants, who had an average age of 35, then completed four separate personality questionnaires.

The first measured their levels of aggression by asking them to rate how much statements such as 'Given enough provocation, I may hit someone' sounded like them.

For the second, participants were asked to rate how strongly they agreed or disagreed with statements designed to assess the personality traits of Machiavellianism, psychopathy and narcissism.

Example questions in each of these sections included 'I tend to manipulate others to get my way', 'I tend to be callous or insensitive' and 'I tend to want others to pay attention to me', respectively.

Next, the participants answered questions relating to the 'Big 5' personality dimensions of extraversion, agreeableness, conscientiousness and emotional stability.

And lastly they completed the Comprehensive Assessment of Sadistic Tendencies, which assesses a person's tendency towards 'everyday sadism'.

This involved rating on a scale how much they agreed or disagreed with statements such as 'When making fun of someone, it is especially amusing if they realise what I'm doing', and 'I enjoy tormenting people'.

Participants were asked to rate how much they liked a range of sweet, salty, sour and bitter foods (dark chocolate pictured) before completing a serious of personality questionnaires. In addition to exhibiting dark personality traits, agreeableness was negatively correlated with bitter taste preferences, said the researchers

THE 'THRILL' OF BITTER FOODS Although the researchers didn't investigate why people with these traits prefer bitter foods, they suggested that they may experience a kind of 'thrill' from them. In the wild, bitter plants tend to signal that they may be poisonous, which is why many of us find bitter tastes aversive. But for people with sadistic traits, eating bitter foods may be 'compared to a rollercoaster ride, where people enjoy things that induce fear', said study author Christina Sagioglou. 'We found particularly robust correlations with everyday sadism,' she said. 'Everyday sadism is a construct related to benign Masochism - the enjoyment of painful activities - , which was first described and investigated by psychologist Paul Rozin. 'To quote Paul Rozin for an explanation: "For the case of innately aversive foods, there may be pleasure from the fact that the body is signalling rejection, but the person knows there is no real threat".' Advertisement

A similar experiment with a further sample of 450 people was then carried out, which confirmed the findings of the first.

'General bitter taste preferences emerged as a robust predictor for Machiavellianism, psychopathy, narcissism and everyday sadism,' the researchers wrote in the journal Appetite.

Agreeableness – the extent to which a person is kind, sympathetic and cooperative– was negatively correlated with bitter taste preferences, they added.

Although the researchers were not investigating why people with these traits prefer bitter foods, they suggested that they may experience a kind of 'thrill' from them.

In the wild, bitter plants tend to signal that they may be poisonous, which is why many of us find bitter tastes aversive.

But for people with sadistic traits, eating bitter foods may be 'compared to a rollercoaster ride, where people enjoy things that induce fear', said study author Christina Sagioglou.

'We found particularly robust correlations with everyday sadism,' she said.

'Everyday sadism is a construct related to benign Masochism - the enjoyment of painful activities - , which was first described and investigated by psychologist Paul Rozin.