In an effort to safeguard young people from the ills of digital life, policymakers around the world have been instituting forced distance between teenagers and their tech. Australia banned social media for those under 16 in December, and New York joined more than a dozen other states in banishing cellphones from the classroom this fall.

Some young people, though, are not waiting for government intervention to re-evaluate their closeness with technology. On the dorm’s staircase that evening, 20 St. John’s College students who had decided to take part in Ms. Fagan’s experiment nibbled on zucchini bread and dashed off last messages to their friends.

The undertaking was being called a “tech fast,” and there had already been some debate over which technology was actually the problem. Most people in attendance said they were interested in cutting back on smartphone use and social media, not, say, shutting off the overhead lights. “We should maybe call it an ‘electronics fast’ or something, but that sounds less cool,” said Jackson Calhoun, 21, a sophomore.

St. John’s College, which has another campus in Annapolis, Md., is in some ways an ideal setting for such an exercise. The school’s Great Books curriculum is focused on reading original works of thinkers like Archimedes, Descartes and Einstein. Classes are discussion-based — no laptops allowed — and each dorm room on campus is equipped with an oatmeal-colored landline.

Several students participating in the fast said they could feel their focus sharpening. Still, the end of the semester loomed, and Samuel Gonzalez was considering just how tech-free he could go without taking a hit to the quality of his final papers.

“Unfortunately, there’s a practical reality that I have to produce 30 pages of writing in the next two weeks,” said Mr. Gonzalez, 29, a senior who was carrying his copy of Einstein’s “Relativity” to class. He briefly pictured himself writing them on a typewriter, then decided to use his laptop, so long as it was in the school library.

Others were realizing just how much they relied on their phones to track one another down. Ms. Weiss had lent Mr. Ponzi a pillow, but could not find him to get it back. Ms. Garrett was out of breath from racing around campus, trying to find a friend who had borrowed her car keys. In the dining hall, students had set up a blackboard where they could exchange notes.