NOT LONG AGO, as happens almost every day, I got a Skype call on my smartphone from my dad, who lives in Kolkata, India. My dad is 79 and doesn’t get out very much, having become increasingly housebound. On this day, I was traveling by train from Denmark to Sweden. Speaking to him, I held my phone up against the window, its camera lens facing out. We both took in the view of the Swedish countryside as the train pulled out from Malmo and sped toward Lund. For a brief while, it felt like we were traveling together.

For that moment of connection, and many others like it, my phone deserves my gratitude. But the same device has become a source of relentless distraction in my life, intruding upon my attention with frightening regularity and diminishing my in-person interactions with family and friends. On a visit to Kolkata to see my dad, I found myself reaching for my phone every few minutes in the middle of our conversation to scan my Facebook feed and see if a photo I’d recently posted had garnered any fresh likes. (It had! And comments, too!)

Over the past decade, smartphones have revolutionized our lives in ways that go well beyond how we communicate. Besides calling, texting, and emailing, more than two billion people around the world now use these devices to navigate, to book cab rides, to compare product reviews and prices, to follow the news, to watch movies, to listen to music, to play video games, to memorialize vacations, and, not least of all, to participate in social media.

The reason why it’s become so hard for us to set aside our phones, even at mealtimes, isn’t hard to understand. “It’s well known that if you want to keep a person dialed into something, give them a reward at variable times,” explains Ethan Kross, a psychologist at the University of Michigan in Ann Arbor. “Turns out, that’s exactly what email or social media does—you don’t know when you’ll get another like or receive your next email, and so we keep checking.”

Read the full article at National Geographic.