March 15, 2001 -- Ever wonder why Dustin Hoffman's autistic character in Rain Man could memorize every name and number in the phone book, but thought that a candy bar and a car each cost 50 cents?
"Autistic individuals don't use context to enhance their memory and learning the way most people do," David Beversdorf, MD, an assistant professor of neurology at Ohio State University in Columbus, tells WebMD. "Normal individuals use context to help categorize and remember new information."
Most people couldn't care less about the telephone book but can remember the phone numbers of family, friends, and business associates because this information means more in the context of daily life. And if you find yourself with an extra 50 cents burning a hole in your pocket, you'll remember that the price of a candy bar is within your reach, but the price of a shiny new Ferrari is light years away.
Although autism severely limits social and work skills, which depend heavily on cues taken from context and setting, it may actually improve memory tasks not dependent on context, Beversdorf found in a study published last year in Proceedings of the National Academy of Science.
People without autism asked to remember a list of words like "thread," "pin," "eye," "sewing" -- and other terms related to the word "needle" -- were more likely than autistic people to assume that "needle" was on the list, even though this "memory" was false.
With aging, more "false memory" errors pop up, which Beversdorf suggests may represent a way our brain compensates for our failing memory.
"If we can't keep track of picky details as we get older, we use contextual cues to help us remember the gist of things, although the specifics may be inaccurate," he says.
Even when you're young, your eyes and your mind may play tricks on you. Eyewitnesses who think they remember a crime may identify the wrong person from a lineup.
"We feel that we see and retain everything around us, much as a video camera records all of the details, and that with the correct cues or aids we could somehow recall everything we saw," says Daniel J. Simons, an assistant professor of psychology at Harvard University. "In reality, our memory is far less accurate than this."