If you can count the number of good friends you have on two hands, you might have a few more fingers spare than you thought after reading this. Researchers believe that when it comes to social bonds, our judgement is actually quite poor, and only half of the people we consider as friends actually feel the same way. A recent study suggests this poor judgement of who our friends are could have knock on effects when it comes to influencing and co-operating with others. According to the team, led by researchers at Tel Aviv University, understanding these limitations could boost performance for companies and social groups that rely on social influence for action. “It turns out that we’re very bad at judging who our friends are, and our difficulty determining the reciprocity of friendship significantly limits our ability to engage in cooperative arrangements,” explained Dr Erez Shmueli, a researcher at Tel Aviv University. “We learned that we can’t rely on our instincts or intuition. There must be an objective way to measure these relationships and quantify their impact.” In social experiments, 84 mature students were asked to rate each other on a scale from one to five, with one being a stranger, three a friend and five indicating one of their best friends, to see how people reciprocated and marked similar responses for each other. While students thought that most of the friendships would be reciprocated, the study revealed just over half of those friendships matched – with a score of one to three. This was backed up with survey data from 600 students in Israel, the US and Europe, which found a similar mismatch in the levels of who people thought of as friends compared to those who reciprocated. Using this information, they developed an algorithm to work out whether friendship was a one-way deal or whether it was reciprocal. “We found that 95 percent of participants thought their relationships were reciprocal,” said Dr Shmueli. “If you think someone is your friend, you expect him to feel the same way. But in fact that’s not the case, only 50 percent of those polled matched up in the bidirectional friendship category.” What’s more, they were able to predict with high accuracy in which direction the friendship between two people would work, depending on how their social circles overlap and their difference in social status. “Our algorithm not only tells us whether a friendship is reciprocal or not. It also determines in which direction the friendship is ‘felt’ in unilateral friendships,” added Dr Shmueli. According to the team, the reason friendships working both ways is important is all down to influence. The closer a person is to another, the more they can exert peer pressure and socially influence them, which could affect their behaviour. The findings were published in the journal PLOS One.