The Secret to Deepening Friendships Is Hiding in Your Phone

This is Day 4 of the 5-Day Friendship Challenge. To start at the beginning, click here.

If you’re like me, you have a staggering number of photos saved to your phone. Does that speak to an unhealthy tendency to obsessively document even the most mundane moments? Perhaps. But today’s objective is to put your photo library to good use.

Nostalgia can be beneficial. It can curb stress and help combat feelings of loneliness. And looking back on old memories with a friend instantly makes you feel more connected, said Marisa G. Franco, a psychologist and the author of “Platonic,” a book about maintaining friendships. Something as simple as looking at an old photo of you and a friend may remind you of the depth of that bond, she said.

In fact, Dr. Franco said, one of the easiest ways to make new friends in adulthood is to simply reconnect with old ones. Revisiting cherished memories can give a fizzled friendship a much-needed jolt.

Friendship Challenge Day 4: Reminisce with a friend.

Text or email a photo or video. This is the quickest option, Dr. Franco said. You might work some details into an accompanying message, such as “I’m thinking about this moment we had together, and this is what it meant to me.”

Dig up some old photo prints. Those 8 x 10s and 5 x 7s that are just gathering dust in storage? Upload them digitally and send them to a group chat. Or have a pal come over and comb through them together while eating snacks.

Ask: “What do you remember?” Simply chatting about your shared experiences can clue you into a friend’s perspective, said Eric Kim, an assistant professor of psychology at the University of British Columbia. When recalling that camping trip you both went on years ago, you may only remember the mosquitoes and restless sleep. But talking to your friend could remind you of the beautiful waterfall you saw and the s’mores you ate.

You get new insights into a shared memory, Dr. Kim said.

Yes, reminiscing can be bittersweet. You might find yourself remembering friends who are no longer alive, or staring at a photo from a more carefree time. But you can also feel gratitude for the time you’ve shared. (And small, daily doses of gratitude have known benefits.)

“Part of reminiscing might be saying, ‘I’m so glad we had that experience together,’” said Julianne Holt-Lunstad, the director of the Social Connection and Health Lab at Brigham Young University. “Or, ‘I’m so grateful we were able to do that.’”