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Knowing Who Your Friends Are May Be Harder Than You Think

Knowing Who Your Friends Are May Be Harder Than You Think

A new study suggests that only half of the people you think are your friends consider you their friend.

That’s because people have a poor perception of friendship ties and this limits their ability to influence their “friends,” according to researchers from Tel Aviv University (TAU) and the Massachusetts Institute of Technology (MIT).

“It turns out that we’re very bad at judging who our friends are,” said Dr. Erez Shmueli, who conducted the study with Dr. Laura Radaelli, both of TAU’s Department of Industrial Engineering, in collaboration with Professors Alex Pentland and Abdullah Almatouq of MIT.

“And our difficulty determining the reciprocity of friendship significantly limits our ability to engage in cooperative arrangements. 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.”

The researchers conducted extensive social experiments and analyzed the data from other studies to determine the percentage of reciprocal friendships and their impact on human behavior. They also examined six friendship surveys from some 600 students in Israel, Europe and the United States to assess friendship levels and expectations of reciprocity.

They then developed an algorithm that examines several objective features of a perceived friendship; that is, the number of common friends or the total number of friends. The algorithm is able to distinguish between the two different kinds of friendship: unidirectional or reciprocal, according to the researchers.

“We found that 95 percent of participants thought that their relationships were reciprocal,” Shmueli said. “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.”

Why is this important?

“Reciprocal relationships are important because of social influence,” said Shmueli, who used the “FunFit” social experiment in the course of the research. “In this experiment that analyzes different incentives for exercising, we found that friendship pressure far outweighed money in terms of motivation. We found, not surprisingly, that those pressured by reciprocal friends exercised more and enjoyed greater progress than those with unilateral friendship ties.”

The researchers said they found that their “friendship algorithm” determined with an extremely high level of accuracy the reciprocal or unidirectional nature of a friendship.

“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,” Shmueli said.

The study was published in PLoS One.

Source: American Friends of Tel Aviv University
Group of friends photo by shutterstock.

Knowing Who Your Friends Are May Be Harder Than You Think

Janice Wood

Janice Wood is a long-time writer and editor who began working at a daily newspaper before graduating from college. She has worked at a variety of newspapers, magazines and websites, covering everything from aviation to finance to healthcare.

APA Reference
Wood, J. (2018). Knowing Who Your Friends Are May Be Harder Than You Think. Psych Central. Retrieved on December 5, 2020, from
Scientifically Reviewed
Last updated: 8 Aug 2018 (Originally: 7 May 2016)
Last reviewed: By a member of our scientific advisory board on 8 Aug 2018
Published on Psych All rights reserved.