London - It is often said that opposites attract. Now psychologists agree – but only for explaining why people become best friends.
In the first academic study of its kind, researchers analysed combinations of people who became best friends and found that their relationships thrived because of the differences in their personalities.
But while it concluded that close friendships work because a pair are not like two peas in a pod, they also found that when it comes to romance, partners should be “largely similar”.
Researchers asked students to describe themselves and their best friends with a personality index based on traits such as openness, conscientiousness, agreeableness, and neuroticism.
It found that the person most likely to be chosen as a friend is someone who is extrovert, agreeable, emotionally stable, conscientious and open to change, or an “EASCO” for short.
Such extroverts find it easier to make friends quickly, the study found, but often need a more introverted friend to balance them out.
So they often form friendships with quieter people who can tease, challenge and calm them, the team at Keystone College, a private university in Pennsylvania, said.
These include the IDCNO (introverted, tough-minded, conscientious, neurotic and open to change) type, described by the college’s Dr Steven Howell as the “quiet, anxious” friend who “thinks about risks and is still willing to try it”.
But the IDCNO also comes with “baggage” so tends to choose a tougher type for a friend who helps them by ignoring problems. Then there is the IDUNT (introverted, tough-minded, restless, neurotic and traditional) who will tend to choose as a best friend someone who is more agreeable and open than they are.
Researcher Kelsey Edelmann said: “Friendships work best with a certain amount of opposite attracting. This makes it different from a romantic relationship, where it helps if you are largely similar.”
The “bonding analysis” study also found that a drinking session is a good way to test and even deepen the relationship between friends.
This was because it allows people to find out who they can rely on when they are vulnerable.
Dr Howell said: “When you have been drinking, when you are exchanging confidences and taking risks in your circle, you cannot fake friendship. You send out an honest signal about whether you can be trusted.
“The guy or girl, it works worldwide for both genders, with the black eye who drags you out of the dumpster after the bar fight is the true friend.”
The research suggested that those who drink together and tackle a crisis together, even if it is only something as minor as how they are going to get home afterwards, are likely to become closer than people who do not drink and avoid such shared dramas.
This was found to apply to both extroverts and introverts.
Dr Howell, quoted in the Sunday Times, said: “However badly they behave, or whatever spouses or other friends may think in later years, such friendships can last a lifetime.”