Rob Sheffield, a veteran rock and pop culture critic and staff writer for Rolling Stone magazine, wrote in his memoirs that nothing brings to life the times you lived through and the people you shared those times with like an old mixtape. Maybe to some. But I will argue that photos can do just the same.

There's a subreddit dedicated exclusively to nostalgia with over 853,000 members. There, people share photos, reminiscing about the past, and they hit right in the feels as much as a mixtape should. From the torture device known as the "Sit and Reach" test to "the pipes" screensaver we all were watching for entertainment at one point in our lives, it has it all.

"Whether it's an old commercial or a book from your past, it belongs in /r/Nostalgia," the mods said about their subreddit, adding that the content can be both humorous and sad. So grab your rotary phone and invite your friend over — this is going to be a wild ride.

#1 Remember Watching The Pipes Screensaver?

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Experts say that small literature on the psychology of nostalgia has developed over the past decade. Mostly, research shows that people engage in nostalgic reverie when they're feeling down in an attempt to boost their mood and self-confidence.

Experimental evidence indicates that we experience nostalgia as an overwhelmingly positive emotion. In fact, it can not only boost our mood but increase a sense of meaning in life as well. Indulging in nostalgia also raises self-esteem and optimism for the future.

However, the University of Southern California psychologist David Newman and colleagues argue that these findings have more to do with the experimental setup than to the true nature of nostalgia.

#2 Pencils With Cartridges

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Their study produced two very interesting outcomes. The first was that people felt more nostalgic when they were with family and friends or when they were eating than they did when they were at work or school.

One explanation could be that family, friends, and food all serve as what psychologists call "retrieval cues." They trigger memories. People can use retrieval cues intentionally, for example, post a to-do list on the refrigerator door. But they emerge unintentionally too, as for instance when a whiff of apple pie aroma reminds someone of their grandmother because she baked them all the time.

#3 Overhead Projector

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The second key finding was that people experienced nostalgia more when they were feeling depressed than when they were happy. At first glance, this result appears to contradict the outcomes of induced nostalgia in the laboratory, where remembering happy events from the past resulted in a boost in mood.

However, some argue that the study by Newman and colleagues was correlational in nature. Participants were not divided into separate conditions and treated differently. Rather, at each measurement, each respondent reported on their current mood and whether or not they felt nostalgic. And what the researchers found was that nostalgia and low mood co-occur.

It could mean that nostalgia leads to negative emotions. But it could also be that people engage in nostalgia when they’re feeling down.