A friend of mine who teaches undergraduates provided insight into something I see regularly but don't experience in the thoroughgoing way he does, namely, young people (and some not so young) who appear to be entirely an appendage of their cellphones. One study concluded that "[t]he average college student uses a smartphone for about nine hours each day."
The take on cellphones is that you can customize them to give you exactly what you want. You are in charge. The trouble with this reasoning is that someone else is programming the apps you use; and those apps are programmed to get you to do certain things in certain ways that are generally to the advantage of the companies providing the apps and to advertisers (sometimes one and the same). These apps may be useful to you, but they are certainly not your apps; they are not actually customized. And, they only offer the illusion of control.
Moreover, there is no app I know of designed to get you to stop looking at your cellphone and focus on the world around you or on your inner life. Some people listen to music or podcasts on their cellphones while they exercise, walk, drive, study, read, eat, or do practically anything. I'm all for listening to music and podcasts. But some of the activities listed above are actually great all by themselves.
Then there is the constant texting. Texting is very useful, I find, for telling people I'm running late to a meeting, inviting people to something at the last minute, coordinating family hordes on vacation and so forth. My professor friend tells me that many of his students say they prefer texting to face-to-face encounters. One student went so far as to characterize face-to-face conversation as a form of "aggression." When my friend first told me this, I had the horrifying realization that it's possible that many groups of young people I see texting while standing in a group may actually be texting each other! (Perhaps I'm extrapolating things too far.)