Alex Mullen, left, this month memorized the order of a set of playing cards in record time: 18.65 seconds. ( Karen Pinson/USA Memory Championship)

How quickly can a person memorize the order of a shuffled deck of cards? Early this month, a medical student named Alex Mullen set a world record: 18.65 seconds.

To the crowd gathered around Mullen at the USA Memory Championship in Hershey, Pa., as he flipped through 52 randomly arranged cards, it was unbelievable that he could look at all of them so quickly, much less commit their order to memory.

“I don’t really have a good explanation for why I’m particularly good at this, but it’s not because I have a naturally good memory,” said Mullen, who set the record at this year’s contest, which he went on to win.

A former swimmer and tennis player who wore sweat pants to the event, Mullen credits his achievement to his competitiveness. Like other people who are sometimes called “memory athletes,” he believes that an exceptional memory is not necessarily something you’re born with but rather a skill that can be developed. Three years ago, he began a training routine that called for half an hour a day of practicing for “memory sports” events.

Memory sports test what psychologists call semantic memory — the ability to recall facts about the world around us (as opposed to episodic memory, the recall of events in our own lives).

Scientists have only just begun to understand how memory works. Certain regions of the brain are known to be important for forming memories, but the exact mechanisms that allow us to store and retrieve information, and the limits of this ability, are still uncertain.

The memory championship included an event in which competitors were given five minutes to memorize strings of random numbers. Mullen managed 483 digits. (He holds the world record for the most numbers memorized in an hour: 3,029.) Participants next tried to commit 117 names and faces to memory in 15 minutes and then had 15 minutes to master a previously unpublished poem 50 lines long, including its punctuation.

The memory athletes attempting these tasks ranged in age from 13 to 62. They included biostatisticians, real estate developers and truck drivers. Many came from the nearby Hershey High School, which won the team championship for the sixth time. (High schools are a relatively new addition to all this, and there were about a half dozen present.)

To pack information away in their brain, memory athletes try to connect words, numbers and playing cards to visual images. To remember the name “Silas Ray,” for instance, one competitor said he imagined a grain silo illuminated by rays of sunlight behind the relevant face.

“They create associations in their brains that allow them to instantly recall the information,” says Tony Dottino, who founded the memory championship in 1997. “I want people to know that there is so much more that you can do with your intelligence than you ever thought possible.”

Examples of people with naturally good memories highlight the power of association. In the mid-1920s, for instance, Soviet psychologist Aleksandr Luria discovered a reporter with phenomenal powers of recall. Not only could Solomon Shereshevsky memorize vast lists of numbers, he could also recall these sequences more than a decade later. Luria discovered the secret to his ability: Every letter and number Shereshevsky saw triggered his other senses as well — bringing to mind a color, for example, or triggering a sound or leaving a taste in his mouth.

Lacking this unusual synesthesia, which is what this sensory cross-talk is called, athletes in the memory competition used noise-canceling headphones and memory techniques that date to ancient times. One is called the Roman house, also known as the memory palace: Competitors visualize a familiar space such as a childhood home or a college dorm, and place objects related to what they are trying to remember in specific locations. Brad Sundstrom, a dentist from Tennessee who came in second overall to Mullen, described it as a “journey.”

“A good memory is composed of sharp images and crisp thoughts woven together by imagination,” said Frank Felberbaum, coach of a team of high school students from New Jersey.

Keeping these images straight isn’t always easy. For instance, while trying to memorize a deck of cards, Sundstrom mistook his mental image of someone throwing a punch, which he had associated with one card, for the image of someone doing a karate kick, which he had associated with another card. He lost to Mullen in the final round because “I mixed up Jack Hanna and Donald Trump,” two people he had associated with two other playing cards.

Mullen set his record by mentally grouping cards in pairs, with each pair being a pre-memorized object. A king of spades followed by an ace of hearts, for instance, is a hot dog. Memorizing a 52-card deck at a competition, two cards at a time, thus requires remembering 26 objects. If that sounds easy, think about how many possible pairs could show up: Each of the 52 cards could be paired with any one of 51 other cards. That’s 2,652 possible pairs to associate with pre-memorized objects (Mullen uses another trick to cut that number in half, but it’s still quite a feat).

Surrounded by giddy high schoolers after his win, Mullen explained how he uses his memory palaces in his studies at the University of Mississippi Medical Center in Jackson.

“At first I couldn’t figure out how to apply this to my schoolwork,” he said. “I would forget the [medical school] material after a couple days.” Then he discovered that he had to construct a different kind of memory palace; instead of placing visual images in the order he learns them, he groups related information in the same room. And taking one stroll through a medical memory palace isn’t enough to cement this information; he needs to revisit it every few days.

But Muller cautions that learning isn’t just memory. “When I am studying, I always make sure to start with the concepts first,” he said. “I only use a memory palace for the important details.”

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