Regarding the Jan. 9 news article "Investors warn Apple over kids' iPhone use":

As the parent of a teenager who would spend all day on his cellphone if allowed to, I find it frustrating that smartphones do not come with a feature that would inhibit addiction and teach teenagers to regulate their phone use: a way of cutting off access to the most addictive features, such as Snapchat, YouTube and texting, after a set amount of time per day.

It would not be fair for me to delete Snapchat from my son's cellphone since it has become part of the conventional landscape of teenager social life. But my son is home alone every day for several hours when a parent cannot be there to tell him to put the phone down. An app that turned, say, Snapchat off after an hour would encourage teens to limit their social media use and plan its use across the day.

Hugh Gusterson, Washington