[panda-giddiness]

> A friend of mine has a terrible Instagram addiction, yet has developed for himself a certain degree of cinephilia lately -- we've watched long movies together in theaters and not once has he been on his phone during the screenings. When one has faith that sustained attention might hold more value than that gained by interruption, they tend to prioritize the former.

I'm not convinced that you've fingered the reason. Pulling out your phone at the theater is considered anti-social behavior, comparable to conversing with your seatmate, and that sort of normative pressure can overcome a compulsion. It's like claiming that someone couldn't possibly be an alcoholic because they don't drink on the job.

A better test would be: What does your friend do when you watch a movie at one of your homes, where there's a lesser expectation to tuck away one's phone? Does he still watch the movie attentively, or does he check his phone every so often?