The Personal and Private Nature of Smartphones:

because smartphones are considerably more personal and private than PCs, using them activates intimate self-knowledge and increases private self-focus, shifting attention toward individuating personal preferences, feelings, and inner states

This is precisely the kind of thing I’m talking about what I complain that the idea that social media is bad is too simplistic. The effects of social media are extremely unclear, because we’re responding to an environment that’s unclear (see also this). Social media might be problematic, but probably the effects have much deeper roots than simply that.

See also amusing ourselves to death, on the medium and the message.