Are My Friends Really My Friends?

“You’ve got enough friends, a new one is bad for you,” says a petulant character named Max in “Kicking and Screaming,” Noah Baumbach’s 1995 cult movie, when a member of his post-collegiate quadrumvirate attempts to introduce a fifth guy. “You start spreading your affection around and it runs thin, believe me.”

The two-decade-old reference may feel dated, but consider the period the film was set in and the ways its characters interact. Landline conversations are routine. Lengthy answering-machine messages and postal mail play a significant emotional role. Friends gather at bars with no external distractions and little chance of making plans with other people on the fly.

It seems antique and quaint compared to how 20-somethings now socialize. Gone are focused landline calls, long recorded voice messages, snail mail (perhaps even long emails). Nights out with friends are interrupted by the immediate posting of frequently taken photos and other attention-diverting phone applications.

In hindsight, the movie’s time — the ’90s — was the last decade that had relatively few technological obstacles to traditional levels of friendship “thickness.” Social media and smartphones spread affection around more easily; friendships may run thin.

“My net is cast wider” now than in the past, said Lucy Schiller, 29, a recent graduate of the nonfiction writing program at the University of Iowa. “It’s a lot easier for me to engage casually with a greater number of people. I don’t know if this is a byproduct of aging, but it seems like the parameters of friendships have changed. I’d like to think they involve long walks and talking at length in person and involving yourself in shared activities, but at this point it feels like those structures have been relegated to the past and we’re skating along through very fun but very lightweight interactions.”

Two statistics from the General Social Survey in 1985 and 2004 are often invoked regarding the influence of new technology on close friendships and social isolation. The average number of confidants people said they had dropped from 2.94 to 2.08 over that time, and the number of those who had none at all went from one-tenth to nearly one-quarter.

Taken on their own, these numbers are a damning indictment of internet-era connections, even if social networking was in its MySpace-Friendster infancy in 2004 and the iPhone did not exist.

But in 2011, a team of researchers at the University of Pennsylvania headed by Keith N. Hampton found evidence that “close social relations do not attrite with internet use and that internet users tend to have larger personal networks,” and that social isolation was actually lower in 2008 than in 1985.

The researchers also determined that the network size of “core discussion confidants” is most strongly associated with two popular social media activities: instant messaging and uploading photos. People who have a mobile phone and engage in these activities have a network 34 percent larger than those who don’t.

Other papers by Dr. Hampton argue that the internet and social media can facilitate offline social connections. One states that “internet use may be associated with higher levels of participation in traditional settings that support the formation of diverse networks,” such as visiting public spaces or knowing more people in the neighborhood. Another suggests that frequent Facebook users have more close and more diverse social ties than the average American — though roughly the same number of overall connections.

Wedding and Funeral Guests

These findings jibe with the research of Robin Dunbar, a professor of evolutionary psychology at Oxford. He has theorized that “group size” of both humans and nonhuman primates — the number of people (or, say, chimpanzees) one can maintain social cohesion with — correlates to “relative neocortical volume,” or the ratio of the neocortex to the rest of the brain.

The oft-cited “Dunbar’s number” is an average of 150 casual friends for humans (really, a range of 100 to 200). These are the people who might come to your wedding or funeral.

Within this roster, there are embedded layers of intimacy that grow smaller by a factor of three: 50 of these make the next cut to buddies, about 15 are good friends, around five confidants form our circle of trust, and finally we have an average of 1.5 people we deem our closest relationships. (Conversely, we can keep track of roughly 500 acquaintances and 1,500 faces we can match to names.)

One may presume that boasting thousands of social media friends or followers would inflate Dunbar’s number, but Dr. Dunbar said that is “absolutely not at all” the case. In a recent paper analyzing Facebook and Twitter data, and another one looking at mobile phone calls, his team determined that people still “showed the same frequencies of interaction as in face-to-face relationships” for the corresponding layers of intimacy, he said.

However, digital media channels “don’t distinguish between quality of relationships,” he said. “They allow you to maintain relationships that would otherwise decay. Our data shows that if you don’t meet people at the requisite frequencies, you’ll drop down through the layers until eventually you drop out of the 150 and become ‘somebody you once knew.’ What we think is happening is that, if you don’t meet sometime face to face, social media is slowing down the rate of decay.”

The result, then, can be a glut of old acquaintances that are not as easily forgotten online and which therefore stifle the development of newer, in-person friendships.

“Your available social time is limited, and you can either spend it face to face or on the internet,” Dr. Dunbar said. If it’s spent with people who are “remote,” whether geographically or just because they’re represented digitally, “you don’t have time to invest in new relationships where you are.”

Whither Rapport?

People from our past that we no longer directly communicate with but who are active on social networks can “colonize valuable space in your mind, and you think about them instead of about your close friends,” said Carlin Flora, the author of “Friendfluence: The Surprising Ways Friends Make Us Who We Are.”

“If my high-school friend posts frequently about her life, it’s almost like it’s celebrity gossip, or it’s akin to me watching a reality show about her,” Ms. Flora said. “Our brains get confused about whether we know celebrities; if we see someone a lot, our brain thinks we know them.”

Of course, thinking we know people through status updates (or paparazzi photos) is not the same as spending time with them, just as dashing off “Happy birthday!” on someone’s Facebook wall has less emotional impact than saying it in person or over the phone.

Ms. Flora did note the advantages of digital media for introverts and people susceptible to loneliness, namely that it is less risky and enervating to make contact through a text or post than through a phone call or an invitation to meet.

With this lower threshold for maintaining friendships, some people strongly favor mediated interactions over in-person interactions, especially millennials accustomed to constant communication via devices.

Ms. Schiller, the Iowa graduate, goes out often with friends at night but also subsists on a digital diet of texting (heavily enough that she recently strained her thumb), Google Chat and social media. She said she finds conversation on Google Chat banal, likely because she tends to use it as she multitasks on her computer, but sometimes opens up more to people via the confessional space of a text message than she might across a table.

As with many millennials, talking on the phone was never a big part of her routine and is now reserved for the rarest of occasions. “I’ve asked people over Gchat if they want to talk on the phone, and they hem and haw,” she said. “It can feel draining — there isn’t a casual component to it.”

There are physiological benefits to face-to-face encounters, however, that do not accrue to digital interactions or the phone. “Your blood pressure goes down, you have synchrony, you mimic your friend’s posture unconsciously,” Ms. Flora said. “It’s a rapport humans have developed over thousands of years, and you don’t get that when you only follow someone on social media.” (Skype et al. can be comparable, though, Dr. Dunbar observed.)

But now it’s common for this synchrony to be disrupted in person, thanks to the ubiquity of the smartphone. Imagine Edward Hopper’s 1942 painting “Nighthawks” recomposed today, with the three late-night diners and counterman all gazing at screens.

“If there’s a bunch of guys at a bar together and they’re all on their phones,” Dr. Dunbar said, “they’re not doing much to trigger the endorphin system to create the sense of bondedness.”

Because members of Generation X such as Ms. Flora based the passionate friendships of their youth primarily on in-person interactions or “rambling” phone calls, when they “make the transfer” to digital friendships they “can take advantage of the benefits of it,” she said. “But for younger people, I would worry about them compromising that precious face-to-face time, not sensing or adjusting to what their friends are really thinking or feeling.”

Speaking of her generation’s possibly diminished capacity for deep friendships, Ms. Schiller issued an unintentionally resonant qualification.

“It might just be me,” she said.

Teddy Wayne is the author of three novels, most recently “Loner.”