I've seen the 1985 movie Clue more than 100 times.

A statistic like this comes with certain benefits. I can not only tell you who killed Mr. Boddy (or, since the movie concludes with a trio of possibilities, in what order) and how many shots the gun actually fired (hint: one plus two plus one plus one), but also can spot the mysteriously moving pot in the kitchen that disappears between two shots due to a continuity error. These are the benefits of watching the same thing over and over. (The negatives are opportunity costs: For example, I have no idea what a 401k means.)

But why, dear God why, would I watch something, anything, more than 100 times? While not everyone crosses into the deep end and becomes a full-on Deadhead, a good portion of us have that singular movie, television episode, album, or band that we just have to return to over and over again. What drives this obsession with repetition?

Comedian—and, full disclosure: friend—Jimmy Pardo is a super-fan of the band Chicago. By his count, he's seen them 70 times since 1981. “It's not crazy Grateful Dead numbers, but it's still ridiculous,” Pardo says.

Tim Curry in Clue. (Photo: Paramount Pictures)

What is it about this ensemble that keeps bringing him back? It's definitely not the variety. "'Saturday in the Park' every time. There was only one tour where they didn't do '25 or 6 to 4,'" he says. "Other than that, you're seeing the same songs over and over." It's also not the guarantee of seeing an amazing show. "In the early 2000s they just looked bored and tired," he says. "That was kind of when I was saying I'm not going to see them anymore. They're doing the same set list, I can't rationalize spending this money. But as soon as it's announced, 15-year-old Jimmy pops into my body and I immediately buy tickets."

When I posed the question about obsessive viewing/listening to a bunch of Facebook friends, one of the common replies was that it was a kind of “comfort food.” When they were feeling down, or tired, or just ill, they plopped down in front of a tried-and-true emotional savior, instead of expending energy on finding a new and risky alternative. But why is something we've already seen dozens of times still capable of affording us such comfort?

The most obvious reason is something called the “mere-exposure effect.” Quite simply, people prefer things they've previously been exposed to. (Amazingly, this effect also works in the area of odor unpleasantness, possibly solving the eternal conundrum of why one's own flatulence isn't as abhorrent as that from an outside party.) The effect makes sense from an evolutionary point of view: If we've been through a door 100 times and know what's behind it, we no longer have to worry that a predator is waiting beyond the threshold. But how does this relate to re-consumption of media?

“There's this sense that you're actually making the sound happen because you're imagining it into existence before it happens.”

“When you hear [music] a number of times, you end up listening ahead and imagining what's going to come next to the sound before it actually happens,” says Elizabeth Hellmuth Margulis, director of the University of Arkansas' Music Cognition Lab and author of On Repeat: How Music Plays the Mind. “There's this sense that you're actually making the sound happen because you're imagining it into existence before it happens.” It's only through repetition that this “conjuring power,” albeit false, can exist.

Not surprisingly, feeling that we have that kind of power provides us all sorts of joy. In one study, Margulis took challenging contemporary art music—that is, music that purposefully avoids repetition—and digitally altered it to have repetitive moments. She played participants both versions and asked them which they enjoyed more. They chose the versions with her alterations. “They thought it was more likely to be crafted by a human artist rather than randomly generated,” she says.

(Repetitive viewing may produce the same kind of calming effect as a meditative chant. “Have a friend say the same word 50 times, and after a while it starts losing any sense of meaning it initially had,” Margulis says. “Your attention shifting from semantic level of meaning to some hyperawareness of the sounds themselves.”)

But there's something beyond the simple joy of repetition. A whole lot of how much we enjoy something depends on the memory associated with that first experience.

The first time Pardo saw the band Chicago was at a 1981 ChicagoFest performance at Navy Pier, and it was an electric performance. He saw them again in 1982 ChicagoFest, and it was the greatest concert he'd ever been to. “There was an energy on the stage,” Pardo says. “I know that I keep trying to get the feeling back from that concert. A lot of [seeing them over and over] is chasing the dragon.”

Many members of that unscientific Facebook poll were exposed to the work in question as a child. “The Blues Brothers taught me how to swear inappropriately,” recalled one friend. “I re-watch it because it takes me back to that time, every time.” This was a common reply. And I can relate to it: 70 percent of my Clue viewings took place before I hit the age of 20. What is going on with this youthful period when we latch onto certain things and don't let go?

A possible explanation may be found in the “reminiscence bump.” Studies have shown that elderly people recall a disproportional number of autobiographical memories that occurred between the ages of 10 and 30. The reasons for this aren't entirely clear, but a trio of theories have emerged: These memories are better encoded by the brain because they take place during a period of change followed by a period of stability; they endure because of the sense of identity that forms during that time; they're processed during a person's peak physical condition. Whatever the case, experiences in adolescence and early adulthood are weighted more dramatically than anything that comes before or after.

The documentary Alive Inside gives us a glimpse of how this can be used for medical benefit. It follows Dan Cohen's non-profit Music & Memory, an organization that helps those suffering from Alzheimer's, dementia, and other cognitive and physical challenges “reconnect with the world using music-triggered memories.” When a patient pops on headphones connected to an iPod with personalized music from his childhood, he nearly completely snaps out of his condition.

This isn't to say that all repetitive views and listens are about the past. In 2012, marketing professors Cristel Antonia Russell and Sidney J. Levy interviewed 23 subjects who had either "'reconsumed' a book, movie, or vacation spot." They discovered that re-consumption gave people the ability to work out problems they were experiencing in the present. "It was helping her work through having an engagement that hadn't worked out," Russell told Scientific American about one subject who was constantly re-watching the movie Message in a Bottle. Every viewing reminded her of her own failed romance, which allowed her to gradually get over her heartbreak. It's akin to desensitization therapy, where people with phobias are slowly exposed to what they're most scared of.

But even if you're not looking to cure your heartbreak, repetition offers an added benefit no matter how many times you re-watch or re-listen. Because, even if the content remains exactly the same, the way one sees and hears it can change dramatically.