It's a startling finding that has prompted much discussion among psychologists, neuroscientists, organizational behavior experts, sociologists and philosophers. Some blame human beings' basic optimism, if not egocentrism, for the disconnect between perceived and actual friendships. Others point to a misunderstanding of the very notion of friendship in an age when "friend" is used as a verb, and social inclusion and exclusion are as easy as a swipe or a tap on a smartphone screen. It's a concern because the authenticity of one's relationships has an enormous impact on one's health and well-being.
"People don't like to hear that the people they think of as friends don't name them as friends," said Alex Pentland, a computational social science researcher at M.I.T. and co-author of a recent study published in the journal PLOS One titled "Are You Your Friends' Friend? Poor Perception of Friendship Ties Limits the Ability to Promote Behavioral Change."
The study analyzed friendship ties among 84 subjects (ages 23 to 38) in a business management class by asking them to rank one another on a five-point continuum of closeness from "I don't know this person" to "One of my best friends." The feelings were mutual 53 percent of the time while the expectation of reciprocity was pegged at 94 percent. This is consistent with data from several other friendship studies conducted over the past decade, encompassing more than 92,000 subjects, in which the reciprocity rates ranged from 34 percent to 53 percent.
Mr. Pentland said it could be that "the possibility of nonreciprocal friendship challenges one's self-image." But the problem may have more to do with confusion over what friendship is. Ask people to define friendship โ even researchers like Mr. Pentland who study it โ and you'll get an uncomfortable silence followed by "er" or "um."
"Friendship is difficult to describe," said Alexander Nehamas, a professor of philosophy at Princeton, who in his latest book, "On Friendship," spends almost 300 pages trying to do just that. "It's easier to say what friendship is not and, foremost, it is not instrumental."
It is not a means to obtain higher status, wangle an invitation to someone's vacation home or simply escape your own boredom. Rather, Mr. Nehamas said, friendship is more like beauty or art, which kindles something deep within us and is "appreciated for its own sake."
Yet one of the most recognized treatises on friendship is Dale Carnegie's decidedly instrumental "How to Win Friends and Influence People." Pop stars like Taylor Swift and Drake are admired for their strategic, if not propagandist, friendships. And, of course, social media sites are platforms for showcasing friendships to enhance personal image.
"Treating friends like investments or commodities is anathema to the whole idea of friendship," said Ronald Sharp, a professor of English at Vassar College, who teaches a course on the literature of friendship. "It's not about what someone can do for you, it's who and what the two of you become in each other's presence."
He recalled the many hours he spent in engrossing conversation with his friend Eudora Welty, who was known not only for her Pulitzer Prize-winning fiction but also for her capacity for friendship. Together they edited "The Norton Book of Friendship," an anthology of works on the topic. "The notion of doing nothing but spending time in each other's company has, in a way, become a lost art," replaced by volleys of texts and tweets, Mr. Sharp said. "People are so eager to maximize efficiency of relationships that they have lost touch with what it is to be a friend."
By his definition, friends are people you take the time to understand and allow to understand you.
Because time is limited, so, too, is the number of friends you can have, according to the work of the British evolutionary psychologist Robin I.M. Dunbar. He describes layers of friendship, where the topmost layer consists of only one or two people, say a spouse and best friend with whom you are most intimate and interact daily. The next layer can accommodate at most four people for whom you have great affinity, affection and concern and who require weekly attention to maintain. Out from there, the tiers contain more casual friends with whom you invest less time and tend to have a less profound and more tenuous connection. Without consistent contact, they easily fall into the realm of acquaintance. You may be friendly with them but they aren't friends.
"There is a limited amount of time and emotional capital we can distribute, so we only have five slots for the most intense type of relationship," Mr. Dunbar said. "People may say they have more than five but you can be pretty sure they are not high-quality friendships."
Such boasting implies they have soul mates to spare in a culture where we are taught that leaning on someone is a sign of weakness and power is not letting others affect you. But friendship requires the vulnerability of caring as well as revealing things about yourself that don't match the polished image in your Facebook profile or Instagram feed, said Mr. Nehamas at Princeton. Trusting that your bond will continue, and might even be strengthened, despite your shortcomings and inevitable misfortunes, he said, is a risk many aren't willing to take.
According to medical experts, playing it safe by engaging in shallow, unfulfilling or nonreciprocal relationships has physical repercussions. Not only do the resulting feelings of loneliness and isolation increase the risk of deathas much as smoking, alcoholism and obesity; you may also lose tone, or function, in the so-called smart vagus nerve, which brain researchers think allows us to be in intimate, supportive and reciprocal relationships in the first place.
"It's huge to have good vagal tone, because it modulates our instinctive fight, flight or freeze response," said Amy Banks, a psychiatrist at the Wellesley Centers for Women who specializes in the growing field of interpersonal neurobiology and is the author of "Wired to Connect: The Surprising Link Between Brain Science and Strong, Healthy Relationships."
In the presence of a true friend, Dr. Banks said, the smart or modulating aspect of the vagus nerve is what makes us feel at ease rather than on guard as when we are with a stranger or someone judgmental. It's what enables us to feel O.K. about exposing the soft underbelly of our psyche and helps us stay engaged and present in times of conflict. Lacking authentic friendships, the smart vagus nerve is not exercised. It loses tone and one's anxiety remains high, making abiding, deep connections difficult.
Comment: More facts about the vagus nerve:
- Stimulating the vagus nerve: Memories are made of this
- Research Shows Vagus Nerve Stimulation Can Help Reorganize Brain
- Scots doctors to help stroke patients 'rewire' their brains by stimulating the vagus nerve
- How the vagus nerve operates in the immune system inhibiting inflammation and stress
- Polyvagal theory: The biological fingerprint for compassion and empathy
- The Neurobiology of Grace Under Pressure: 7 habits that stimulate your vagus nerve and keep you calm, cool, and collected
- Wim Hof, the Iceman, regulates his vagus nerve to withstand extreme cold
So it's worth identifying who among the many people you encounter in your life are truly friends. Who makes time for you? Whose company enlivens, enriches and maybe even humbles you? Whom would you miss? Who would miss you? While there is no easy or agreed upon definition, what friendships have in common is that they shape us and create other dimensions through which to see the world. This can be for better or worse depending on whom we choose as friends. As the saying goes, "Show me your friends and I will show you who you are."
Comment: Indeed, our own mental health is strongly coupled to the quality of our human relationships.