Interesting question. The first thing to mention is that smartphones change the type of sociability among users (and non-users). Smartphone sociability is more often, more direct than communication through regular phones but less direct than face-to-face communication. Friends, partners, colleagues may exchange multiple messages and calls using smartphones through a day. Without smartphones they would have communicated through regular phones and face-to-face contact. Face-to-face contact is of course more direct but it cannot happen as often. Regular phone calls and e-mails contacts were more expensive in the past and did not allow face contact that is allowed from smart phones (facetime, etc.). So, in general, I believe that smartphones have increased sociability but at the same time they have changed sociability. If we consider the quality of sociability perhaps smartphones have an inverse U effect. The frequency and types of communication options may increase quality up to some extent but dependency on smartphones may decrease at some point the frequency, even the quality of face-to-face sociability.

Thank you very much.