Social media butterflies just can’t take a break

“People expect you to be available,’’ said Rich Ling, author of “New Tech, New Ties: How Mobile Communication Is Reshaping Social Cohesion.’’ “It’s become taken for granted you are accessible.’’

Statistics on holiday travelers who feel compelled to feed the Twitter beast or respond to friends’ texts are hard to come by. But smartphone penetration has hit 35 percent of the adult population, according to a study by the Pew Research Center’s Internet & American Life Project.

And in a recent online survey of 1,000 US adults, 54 percent say they use social media on vacation, up from 28 percent in 2010. The survey was commissioned by Marriott.

Expectations for staying in touch are so high that some people feel the need to send out a preemptive variation of the “out of the office’’ auto response.

“I’ve seen people declare, ‘I’m going to be gone for two weeks, so you won’t see me on Twitter or Facebook,’ ’’ said Andrew J. Rosenthal, an MBA student at Harvard Business School. “They’ve built such a strong day-to-day relationship with their followers they need to let them know when they’re leaving town.’’

Few are better positioned to see vacationers’ fear of falling out of the loop than Joe Fernandez, the chief executive and cofounder of Klout, an online firm that measures users’ influence on Twitter, Facebook, and LinkedIn. He regularly hears from people who are despondent, or even angry, that their Klout scores dropped while they took a break.

“Leave town for 3 days for a funeral and my @Klout score drops 8 points,’’ tweeted @asimpson920. “How quickly I am forgotten.’’

Many digital dinosaurs, disgusted family members, and even the plugged-in are quick to brand the 24-seven social media users addicts. But Fernandez disagrees.