The more resonant the images are, the more difficult they are to forget. But even meaningful information is hard to remember when there's a lot of it. That's why competitive memorizers place their images along an imaginary route. That technique, known as the loci method, reportedly originated in 477 B.C. with the Greek poet Simonides of Ceos. Simonides was the sole survivor of a roof collapse that killed all the other guests at a royal banquet. The bodies were mangled beyond recognition, but Simonides was able to reconstruct the guest list by closing his eyes and recalling each individual around the dinner table. What he had discovered was that our brains are exceptionally good at remembering images and spatial information. Evolutionary psychologists have offered an explanation: Presumably our ancestors found it important to recall where they found their last meal or the way back to the cave.
After Simonides' discovery, the loci method became popular across ancient Greece as a trick for memorizing speeches and texts. Aristotle wrote about it, and later a number of treatises on the art of memory were published in Rome. Before printed books, the art of memory was considered a staple of classical education, on a par with grammar, logic, and rhetoric.
Today external aids supplant natural memory: PalmPilots track schedules, cell phones store phone numbers, and Internet searches turn up a bonanza of information. About the only place in modern society where you'll find people still using the loci method is at the World Memory Championships.
Gunther Karsten used to wake up in a cold sweat, worrying that someone with a photographic memory would show up at the competition and blow everyone out of the water. Most scientists say that's not likely to happen. Although some people claim to have a photographic memory, there is no evidence that anyone can actually store mental snapshots and recall them with perfect fidelity.
If photographic memory is a myth, might there be some other form of innately superior memory? John Wilding and Elizabeth Valentine think so. They divide people with superior memories into two classes—strategists and naturals. Strategists, like Karsten, Cooke, and most of the other competitors in memory contests, employ techniques that convert meaningless information into a form the brain can organize and retain. Strategists tend to be exceptional at memorizing only a few types of things. Naturals, on the other hand, show strong memory across a wide variety of tasks and tend to have an easier time holding on to those memories.
The most famous of the naturals was the Russian journalist S. V. Shereshevski, who could recall long lists of numbers memorized decades earlier, as well as poems, strings of nonsense syllables, and just about anything else he was asked to remember. "The capacity of his memory had no distinct limits," wrote Alexander Luria, the Russian psychologist who studied Shereshevski from the 1920s to the 1950s.
Shereshevski also had synesthesia, a rare condition in which the senses become intertwined. For example, every number may be associated with a color or every word with a taste. Synesthetic reactions evoke a response in more areas of the brain, making memory easier. They also create problems. "If I read when I eat, I have a hard time understanding what I'm reading—the taste of the food drowns out the sense," Shereshevski told Luria.
Shereshevski's greatest challenge was learning to forget. He tried writing things down in hopes of discharging their memory. When that didn't work, he tried burning the pieces of paper, but he could still see numbers hovering among the embers. Eventually, he discovered that he could forget information if he convinced himself it was meaningless. "If I don't want the chart to show up, it won't!" he exclaimed. "And all it took was for me to realize this!"
K. Anders Ericsson, a Swedish-born psychologist at Florida State University, thinks anyone can acquire Shereshevski's skills. He cites an experiment with S. F., an undergraduate who was paid to take a standard test of memory called the digit span for one hour a day, two or three days a week. When he started, he could hold, like most people, only about seven digits in his head at any given time (conveniently, the length of a phone number).
Over two years, S. F. completed 250 hours of testing. By then, he had stretched his digit span from 7 to more than 80. He had developed his own strategy for remembering based on his own experience as a competitive runner: He associated strings of random numbers with track times. For example 3,492 was remembered as "3 minutes and 49 point 2 seconds, near world-record mile time."
The study of S. F. led Ericsson to believe that innately superior memory doesn't exist at all. When he reviewed original case studies of naturals, he found that exceptional memorizers were using techniques—sometimes without realizing it—and lots of practice. Often, exceptional memory was only for a single type of material, like digits. "If we look at some of these memory tasks, they're the kind of thing most people don't even waste one hour practicing, but if they wasted 50 hours, they'd be exceptional at it," Ericsson says. It would be remarkable, he adds, to find a "person who is exceptional across a number of tasks. I don't think that there's any compelling evidence that there are such people."
Ericsson contends that Shereshevski must have developed his extraordinary memory through practice using a system that sounds very similar to the loci technique. He cites Luria's description of how Shereshevski remembered lists of random words: "When Shereshevski read through a long series of words, each word would elicit a graphic image. And since the series was fairly long, he had to find some way of distributing these images of his in a mental row or sequence. Most often . . . he would 'distribute' them along some roadway or street he visualized in his mind."
Shereshevski died long before Ericsson began his research, but the psychologist was able to vet the extraordinary memory of another supposed natural, Rajan Mahadevan, who was believed to have a baseline digit span of about 15. Born in India in 1957, Mahadevan could memorize parking lots full of license plates by age 5. For a time, he was listed in Guinness World Records for flawlessly memorizing the first 31,811 digits of the mathematical constant pi (the record now stands at more than 80,000 digits).
In 1987 Mahadevan enrolled as a graduate student in psychology at Kansas State University, where he was employed as a participant in memory experiments. Six years later, Charles Thompson, Thaddeus Cowan, and Jerome Frieman, psychologists at Kansas State, published Memory Search by a Memorist, a book about Mahadevan that concluded, "He seems to rely on raw memory power."
Not long before the book was published, Mahadevan left Kansas State and went to the University of Colorado, where Ericsson was based. While Mahadevan continued to pursue his Ph.D. in Ericsson's lab, he and the psychologist collaborated on more studies of his apparently unique memory. Last year, they coauthored a paper in which they argue that the 1993 book on Mahadevan was wrong. His impressive memory did not derive from any ability but rather from skills developed during the 1,000 hours he had spent reviewing the digits of pi for his Guinness world-record run.
"It would be nice to say that I just have a talent to do it," says Mahadevan. But knowing that his superior memory is an acquired skill is in some ways more important to him. Memory, he says, is "a level playing field, and I prevail under those circumstances. My view is that it does not in any way diminish my achievements."
By the third day of the World Memory Championships, 19-year-old Clemens Mayer from Germany held a commanding lead. He needed only a safe time of about one minute and 30 seconds in the final card-memorizing event to become the first German world memory champion. Karsten was in second place. The other competitors jockeying for position behind them, including Ed Cooke and Ben Pridmore, were all gunning to do a 30-second deck.
Mayer is practically a poster child for Ericsson's ideas about how memory skills can be acquired. What is mysterious about people with exceptional memory, says Ericsson, is not their memory but their motivation. Not many people have the discipline and drive to practice memorizing for the several hours a week needed to compete in the World Memory Championships. Mayer, who had attended a sports academy in East Germany, had hoped to someday become an Olympic runner. Three years ago, he turned on the television and saw Gunther Karsten memorizing a deck of cards. He thought, "I can do that," and began applying the discipline that had made him one of Germany's top young runners. At first, he practiced for two hours a day. Now he spends closer to half an hour, still more than almost anyone else on the memory circuit.
Most memorizers have an Achilles' heel. The digit people are often bad at names and faces. The poem people are often bad at cards. Mayer has no such weak spots. He ranked near the top in every discipline and set a new world record of 198 digits in the spoken numbers event, in which contestants must recall 200 digits read aloud at the rate of one per second.
Mayer managed to memorize a deck in a safe 1:02.7. No one even came close to breaking the 30-second barrier. The best time belonged to Katharina Bunk, a 14-year-old German who was competing alongside her older brother. She managed 45.8 seconds. The 30-second deck would have to wait another year.