Jason Sprung, a 26-year-old comedian in Brooklyn, connected last year on the location-based dating app Tinder with a Tennessee woman who was visiting New York. The two didn’t get a chance to meet up while she was in town, but that didn’t deter them.

“We talked on the phone every day for almost a month and sent a lot of texts and photos and videos and sexts,” Mr. Sprung said. “We’d have phone sex. It felt close to a relationship without actually seeing the other person.”

The couple grew so intimate that the woman promised she would move to New York in six months. Mr. Sprung couldn’t wait that long. “So I broke up with someone I’d never even met before,” he said.

While his primary reasoning was logistical, he acknowledged that there may have been something else behind it. “You build up this rapport” over the phone and computer, he said, “and the expectations that we had of each other were very high. And I realized I’m not that great of a person. There’s no way I’m going to live up to that.”

Mr. Sprung’s story of a non-IRL (“in real life,” for those of a certain age) extended liaison is not unique. More and more technophilic and commitment-phobic millennials are shying away from physical encounters and supplanting them with the emotional gratification of virtual quasi relationships, flirting via their phones and computers with no intention of ever meeting their romantic quarry: less casual sex than casual text.

Contrary to anecdotal claims of the hegemony of hookup culture, several studies suggest young adults are not having as much sex as believed. A 2013 University of Portland study surveyed 18- to 25-year-olds who had completed at least one year of college, comparing results from 1988 to 1996 to those from 2002 to 2010. Fewer respondents from the more recent “hookup era” reported having had sex within the past year (59.3 percent versus 65.2 percent), and lower numbers said they had had multiple partners.

“We are not in the midst of a new era of no-rules-attached sexuality,” concluded one of the study’s authors, the sociology professor Martin Monto.

College students are also more sexually moralistic than one may suspect. A 2013 study from the University of Illinois at Chicago of 19,000 of them found that 73 percent lost respect for either men or women (or both) who they believed hooked up “a lot” (an admittedly subjective quantity).

Obviously, sex is not going out of fashion with 20-somethings, and the simulacrum is not replacing the real thing anytime soon. (Indeed, the Portland study noted that more respondents in the modern period are having casual sex, though this may also be a byproduct of fewer of them having a regular sexual partner or spouse.) But the proliferation of options through online dating, the ease and lower emotional stakes of screen-based communication, and ready access to pornography are producing a generation that sometimes prefers to keep physical relationships at phone-tapping thumb’s length.

Younger men, a demographic not known for pickiness when it comes to flings, may be most susceptible to these paradigm shifts.

Historically, young women “used to have more options on a face-to-face level,” said Sesen Negash, an assistant professor of couple and family therapy at Alliant University in San Diego who has worked at a number of college campuses. That is changing in the post-FaceTime world.

“There’s more accessibility to women that men may not have had before,” she said. “They have multiple apps and websites that they’re on simultaneously. Virtually, there’s that sense that there are so many options that they don’t have to choose.”

As Mr. Sprung suggested, the phone screen is also armor against vulnerability for these men, Dr. Negash said. Will Stephen, 25, agreed. A Brooklyn comedy writer for the website CollegeHumor, he has been on and off OkCupid, Tinder (which he has mined for comedic material) and the app Hinge for three years. Though he has been in contact with dozens of women, he said, he has gone on only three dates.

“My conversations drop off sometimes when I realize the fantasy version of online dating and the reality of it” are at odds, he said. “Then it starts to feel risky in a way it didn’t feel before. And the risk can spook you a little bit.”

Tom Philip, a 23-year-old freelance writer from London now also based in Brooklyn, echoed his anxieties. Mr. Philip has intermittently been active on dating sites or apps for three years as well, he said, engaging in sustained communication with upward of 50 women, but he has met up just once.

“The one date I went on,” he said, “I didn’t want to do it all day and nearly canceled three or four times because it felt like it was going to be a panic room of so much stuff going on.”

Even those who have already made in-person connections sometimes prefer the security of the phone to the anxiety of a romantic-comedy-cum-David Fincher thriller. Marle Cordeiro, 23, a professional poker player and model who splits her time between Manhattan and Las Vegas, recalled a frustrating dialogue with a man who kept asking her to hang out via text, then backed off whenever they set a time. In a similar situation, a friend of hers met a man who lived across the street from her workplace but who never visited.

“He would constantly text her and ask her for selfies,” Ms. Cordeiro said. “They want the idea of this hot girl sending pictures of herself, but they don’t want to make it a reality and find out she has problems or whatever.”

The impulse is often gender-neutral. Mr. Stephen confessed to fishing, at times, for positive responses from dating sites and apps to make himself feel better, a practice endorsed by Hallie Cantor, 25, a writer for “Inside Amy Schumer.”

“It’s a much better app when you don’t message anyone” on Tinder, she said, “because then it becomes a self-esteem boost: Anytime you open it, there’s a list of people who said they would have sex with you. It’s a little validating.”

Since a lot of her matches don’t end up messaging her after an initial expression of mutual interest (swiping right on each other’s picture), it “makes me think others are using it the same way,” she said. “It’s fun to swipe people left or right and be in a powerful position without having to go on an actual date with them and get to know that they’re a disappointing person.”

Swiping, and discovering someone else has right-swiped you, is not only fun; it may affect one’s neurological makeup. “The idea of someone who’s interested in you alters your hormonal state and releases dopamine,” Dr. Negash said, and habitual online daters are “looking for their next high. It’s the drug of choice for many right now.”

As with recreational drug use, tedium is often the catalyst. “Sometimes it’s honestly just boredom,” Ms. Cordeiro said. “It’s Friday and you have nothing to do. The ego boost is totally a thing.”

The ennui-plagued may turn to yet another time-honored stimulus on a Friday night. Dr. Negash has worked on five not-yet-published studies examining the role of pornography in college students’ lives. She found that the consumption of it resulted in lower “support seeking,” she said, meaning it made them less likely to look for friendships and romantic relationships. In addition, people who believe that relationships take effort reported that they were more likely to watch it.

Therefore, young men, especially, who have become chronic viewers of easily accessible pornography may be less inclined to explore the more challenging terrain of three-dimensional partners.

“It’s a one-sided relationship,” Dr. Negash said. “The screen is not asking anything of you. You’re not risking anyone hurting you.”

_____

Last year, I was let go by a company for which I worked as an independent contractor. In the 16 months I worked there, I followed my immediate supervisor on Twitter and Instagram, and she followed me. Social media was part of my job, and one of many areas in which I apparently underperformed. I have since found a similar position with a smaller company in the same industry.

However, my old supervisor and I are still following each other. She does not interact with me, but reading her frequent, chirpy posts reinforces my feeling of having failed. It’s a small industry where everyone knows one another, and social media interactions are hierarchical in ways reminiscent of high school. I would like to unfollow her and put her and the company behind me, but I don’t want to create drama. What should I do? ANONYMOUS, N.Y.C.

This is a good reminder to use caution when mixing work and social media: A boss isn’t always a “friend,” and a former boss, as you’re learning, can be a genuine irritant. At the very least, it’s a good idea to be selective about which social media accounts you use to connect with colleagues.

But sometimes, as in this case, there’s a lot of pressure to “get social” — following co-workers is both expected and, on some level, professionally useful. (Maybe the boss expects to be followed? Maybe, in the context of a “small industry,” monitoring social media indirectly provides useful intel?)

The point is, it sounds as if you had no choice in using these platforms; they were part of your job. And the problems that you’re encountering now are a side effect of the form. Most of these services blend two fundamentally different aspects of human interaction: polite social signaling (“Sure, we are ‘friends’ ”) and an authentic desire to be in touch with someone else’s life. I say “Good morning” to strangers while walking the dog — but that doesn’t mean I want the real-world equivalent of a status update from everyone I greet.

The good news is that many of these tools, supposedly designed for delightful online mingling, are also equipped with features that make it easy to shun and ignore your contacts. Twitter is an example: Click on your former boss’s profile, then click the gear symbol and scroll down to select “mute.” Her tweets will disappear from your feed, but she’ll never know about this snub. Facebook has similar options for covertly tuning out specific friends.

Instagram happens to be among the services that doesn’t make this easy, although there are third-party apps that claim to let you filter your feed. If that sounds like too much hassle, consider whether unfollowing this person would really be such a catastrophe: If she is ignoring you anyway, and has many followers, she may not even notice.

Should you conclude that this is just too risky, all I can suggest is that you filter the way you look at her “chirpy” offerings. Remember that most people offer a sunnier-than-real version of their lives on social media, so just imagine that her every joyous post actually masks an unpleasant tangle of self-loathing and misery.

O.K., that’s not a wholly serious suggestion. But you see where I’m headed: The truth is that whatever is or isn’t going on in your former boss’s life has nothing to do with yours. Keep scrolling until you see something you really enjoy, posted by someone you actually like.

The Samaritans, a well-known suicide-prevention group in Britain, recently introduced a free web app that would alert users whenever someone they followed on Twitter posted worrisome phrases like “tired of being alone” or “hate myself.”

A week after the app was introduced on its website, more than 4,000 people had activated it, the Samaritans said, and those users were following nearly 1.9 million Twitter accounts, with no notification to those being monitored. But just about as quickly, the group faced an outcry from people who said the app, called Samaritans Radar, could identify and prey on the emotionally vulnerable — the very people the app was created to protect.

“A tool that ‘lets you know when your friends need support’ also lets you know when your stalking victim is vulnerable #SamaritansRadar,” a Briton named Sarah Brown posted on Twitter. A week and a half after the app’s introduction, the Samaritans announced it was reconsidering the outreach program and disabled the app.

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Social media posts offer a vast array of information — things as diverse as clues about the prevalence of flu, attitudes toward smoking and patterns of prescription drug abuse. Academic researchers, often in partnership with social media platforms, have mined this data in the hopes of gaining more timely insights into population-scale health trends. The National Institutes of Health, for instance, recently committed more than $11 million to support studies into using sites like Twitter and Facebook to better understand, prevent and treat substance abuse.

Facebook and OkCupid, a popular dating site, have also conducted experiments in which the companies manipulated content presented to their own members to study the impact on their behavior.

Now a handful of research and nonprofit groups are analyzing social media postings with the aim of detecting and predicting patterns in mental health conditions. The experience of the Samaritans highlights the perils involved.

“Social media and discussion websites are producing data sources that are revolutionizing behavioral health research,” said Mark Dredze, an assistant research professor of computer science at Johns Hopkins University who studies social media and health. “You can expect to see tremendous results.”

But translating this population-level data into health predictions and interventions for individuals is fraught. To some leading psychiatrists, the notion of consumer apps like Samaritans Radar that would let untrained people parse the posts of individual friends and strangers for possible mental health disorders amounts to medical quackery.

For one thing, said Dr. Allen J. Frances, a psychiatrist who is a professor emeritus at Duke University School of Medicine, crude predictive health algorithms would be likely to mistake someone’s articulation of distress for clinical depression, unfairly labeling swaths of people as having mental health disorders.

For another thing, he said, if consumers felt free to use unvalidated diagnostic apps on one another, it could potentially pave the way for insurers and employers to use such techniques covertly as well — with an attendant risk of stigmatization and discrimination.

“You would be mislabeling millions of people,” Dr. Frances said. “There would be all sorts of negative consequences.” He added, “And then you can have sophisticated employment consultants who will do the vetting on people’s psychiatric states, derived from some cockamamie algorithm, on your Twitter account.”

In phone interviews, researchers who study social media and mental health disorders said they were proceeding cautiously — and transparently.

For a study published last year, for instance, scientists at Microsoft Research recruited several hundred Twitter users who volunteered to take a standard screening test for depression. The volunteers also agreed to allow the researchers one-time access to their personal Twitter accounts.

For volunteers whose scores indicated they had moderate to severe depression, the researchers analyzed all of their Twitter posts in the year before the onset of their depression and compared those with a year’s worth of posts from volunteers who were not depressed. Among other findings, the researchers reported that the depressed volunteers tended to be less socially active and to post messages that were more negative and more concerned about health and relationships than the nondepressed volunteers.

From those findings, the researchers developed a classification algorithm to predict whether a person was vulnerable to depression. It was about 70 percent accurate when tested on the Twitter posts of the original group of 171 depressed volunteers. Its accuracy in predicting depression in other social media users is unknown.

In a related study, the researchers applied their prediction system to millions of Twitter posts to generate a map of depression across the United States. Their results partly mirrored geographic depression patterns previously published by the Centers for Disease Control and Prevention.

Dr. Eric Horvitz, the director of the Microsoft Research lab at Redmond, Wash., said his group’s studies demonstrated the potential for using social media as a tool to measure population-level depression patterns — as a complement to more traditional research methods.

“We could compute the unhappiest places in the United States,” Dr. Horvitz said. He added that social media analysis might also eventually be used to identify patterns of post-traumatic stress disorder immediately after events like tsunamis or terrorist attacks. “You can see the prospect of watching a news story break and using these tools to map the pulse of society,” he said.

But researchers generally agreed that it was premature to apply such nascent tools to individuals.

“People always ask, ‘Can you predict who is going to try to commit suicide?’ ” said Dr. Dredze, the Johns Hopkins researcher. “I think that’s way beyond what anyone can do.”

The Samaritans developed the Samaritans Radar app in consultation with experts at universities in Scotland and Wales; the academic researchers provided examples of possible suicidal phrases, derived from their own studies of social media posts.

The app sent email alerts to users when anyone they followed posted a potentially worrisome comment. The Samaritans particularly hoped to reach people between the ages of 18 and 35, a demographic that is active on social media and among whom suicide is a leading cause of death.

Initially, the Samaritans suggested in press material that users might monitor celebrities: “Well-known and high-profile people can face the same problems and difficulties as regular people, so there is no reason to think they wouldn’t be appreciative of some extra support from their Twitter followers.” But the day after the app was introduced, the Samaritans said people who did not want their Twitter posts to appear in Samaritans Radar alerts could opt out. 

“We need to use tools such as Samaritans Radar to encourage people to look out for one another online, helping them to reach out and offer support,” Joe Ferns, the Samaritans executive director of policy, research and development, said in a statement at the time.

Susan Golaszewski, a spokeswoman for the Samaritans, said the group was consulting with a variety of outside experts about its app. She declined a request for an interview, saying that the group felt it was inappropriate to comment publicly during the review process.

The Samaritans group was clearly unprepared to address the fundamental fairness and safety questions it raised by offering the public easy access to an unproven diagnostic tool.

“If someone tweets ‘I’m going to kill myself,’ you can’t just jump in,” said Christophe Giraud-Carrier, a computer scientist at Brigham Young University who studies the role of social media in health surveillance. “There are all these psychological factors that come into play that may push someone over the edge.”

He and other academic researchers who have been grappling with these questions say they are unlikely to be resolved anytime soon.

“That doesn’t mean we shouldn’t be doing this research to try to create in-time interventions,” said Munmun De Choudhury, an assistant professor in the School of Interactive Computing at Georgia Tech who studies mental health and social media, and was previously a member of the Microsoft Research team studying depression. “But we have to think very carefully about who gets access to these tools and what the boundaries are for technology used to make judgments about individuals.”

It’s called the “typing awareness indicator,” and a few months ago, my therapist ordered me to disable it on my phone. “It’s causing you too much anxiety,” she said, pointing to the iPhone I had in a white-knuckle grip. “It’s giving monumental weight to matters of a text message.”

But we weren’t even talking about text messages ... exactly. We were talking about the time between text messages. Specifically that little gray bubble with the ellipses that pops up on your iPhone while the person on the other end of your text message is writing a response.

Or, in my case — in the particularly high-stakes conversation at hand — it was the bubble that popped up to indicate typing, then disappeared to show he had stopped. Then came back up to show typing, then went away again. Then returned for what seemed like an eternity (he must be writing something deep, right?) only to produce a response so benign (you know, like “cool” or “ya”) that it could only be topped by the humiliation of the bubble never returning at all (meaning he was flat-out ignoring me). Which I would know, of course, because I could see that he had read my message (that’s called a “read receipt”).

“The three dots shown while someone is drafting a message in iMessage is quite possibly the most important source of eternal hope and ultimate letdown in our daily lives,” said Maryam Abolfazli, a writer in Washington who has tackled the topic. “It’s the modern-day version of watching paint dry, except you might be broken up with by the time the dots deliver.”

For some time, sociologists have studied the way that new technology affects the brain; the way that constant updates prime us to fear we’re missing out, or the way we crave the adrenaline rush brought on by a constant stream of digital micro-communications.

But what about the tyranny of the text bubble? Indeed, there are real problems in the world. But this was the kind of modern-day technological minutiae that had the ability to jail me in a very specific cognitive hell.

“The awareness indicator as implemented on the iPhone is a curious beast — it conveys that something is being done, but it won’t say what,” said Paul Dourish, a professor at the University of California, Irvine, who studies the intersection of technology and society. “It’s curiously coy.”

I’ve taken to calling this the “so and so is typing” feature, as does the man who invented it for the iPhone — a close relative of, but not to be confused with, the “delivered” status and “read receipt,” also staples of modern texting.

The specifics of the feature vary slightly based on the platform. On an iPhone, the bubble appears when you’re messaging another iPhone user; on desktop clients like Google Chat or Facebook Messenger, you’ll receive a “Jessica is typing ... ” blurb. But whatever form it takes, it remains, as my friend Ben Crair put it in a recent essay in the New Republic, “the most awkward part of online chat.”

The roots of the typing awareness indicator go back to the 1990s, when people used dial-up (the horror!). But back then, it had a practical purpose: It let you know when a person was online, or that a message was delivered. Remember the old AOL Buddy List? As the Wired columnist Clive Thompson reminded me, it was perhaps the first popular iteration of this system: a creaking door noise to notify you when a friend signed on, and a door slamming when he or she left.

But it wasn’t until 2005 that BlackBerry became the first big company to bring the “delivered,” “read” and “so and so is typing” features to mobile with BlackBerry Messenger, or BBM. Two years later, Apple introduced the iPhone with SMS, and four years after that, iMessage, which added a real-time element to otherwise jilted conversations.

As technologists describe it, the typing feature rests somewhere between real-life speech, with tone and pacing — what linguists call “synchronous” communication — and text-based communication (“asynchronous”), which occurs in spurts, out of sync, like email. “It’s like eye contact in a conversation: You know if they’re paying attention,” said Gary Klassen, the principal architect at BlackBerry and the lead developer of BBM.

And yet, while desktop communication still comes with the question “Are you there?” on mobile, presence isn’t just expected — it’s mandatory. So the typing indicator has become a message in and of itself, “the equivalent of saying, ‘Hold on, I’m responding,’ ” said Ron Palmeri, the founder of a communications start-up called Layer that specializes in chat technology.

Or ... “I’m not responding.”

Which brings us back to text-bubble anxiety, of which there are many forms.

There’s the text bubble of the highly charged emotional conversation (also known “Aaaah, this next could dictate everything!”) that really shouldn’t be happening over text message in the first place but is because, well, that’s the way we communicate these days.

There’s the giving-away-too-much-without-actually-saying-anything pause, when you start to type and then decide to edit your response. (“You know I can see you typing, right?” a friend recently said to me, as I fumbled over an answer for whether I was mad at her.)

There are the times when the iPhone has actually malfunctioned and you have just worked yourself into a rage for no reason, or the times you blindly convince yourself that it has. “I’ve found this self-delusion quite helpful,” said Sally Kohn, a political commentator.

Or there’s the text you want to pretend you haven’t read yet — but then find that your pocket has pressed against the cursor, which is now in the response tab and, damn, now he knows that you’ve seen it and your whole plan is foiled.

Laura Barganier, a public relations manager in New York, told me recently, “Sometimes I don’t want someone — O.K., likely a boy — to know I’m taking so long to write a text that I start a brand-new blank text and then copy and paste it in the original chain,”

“But don’t you wonder if he wonders how you typed so quickly?” I asked.

“I fake type for a few seconds,” she responded.

As Neal Bledsoe, an actor in Los Angeles, put it (over text message, naturally): “This is the new human condition. We’re all desperate for human connection, and all we get — after all that typing — is a paper-clip emoji.”