Still writing '09 on your checks? It's 'proactive interference'

OK, admit it. We're more than three weeks into the New Year, and you're still writing "2009" on your checks, school papers and office documents.

If so, you may be suffering from "proactive interference."

That's the term neuroscientists use to describe what happens when anything you've already learned interferes with something you're trying to learn.

Larry Squire, a memory researcher at the Veterans Affairs Medical Center and the University of California in San Diego, said the problem isn't unique to switching your checks from 2009 to 2010.

It's what happens when you rent a car for a week that has its stick shift located in a different place, and just when you've finally learned to automatically grab it, you go through the same struggle when your original car comes back from the shop, Squire said.

It's also the culprit when you call your new girlfriend by your old girlfriend's name, added Douglas Rohrer, a psychology professor at the University of South Florida.

Squire said he's not aware of any studies that show how long it typically takes someone to switch over mentally from the previous year to the new one. But chances are that the older you are, the longer it will take, he said.

That's because two brain areas are involved in this task, he said.

One is the hippocampus, a structure that helps form new memories and retrieve old ones. The other is the frontal lobe, which among other things allows us to switch from one task to another.

As we get older, our frontal lobe shrinks, and it's harder to shift our attention from one task to another, he said. "As people get older, they will tell you they have the same capacity to work as always, but they like to be uninterrupted for longer periods."

The date-switching challenge is not a classic case of failing to remember something, Rohrer added, "because anybody can tell you what year it is, unless they have certain kinds of amnesia or dementia."

Instead, he said, "when people perform a certain task in the same way for a long period of time, as they do when they write '09' on their checks for an entire year, the task becomes automatic, and it takes a while to break the habit.

"The same problem would occur if you visited England and had to drive on the left side of the street. If you were driving in an alley after you got back to America, when you suddenly found yourself facing an oncoming car, you might mistakenly veer to the right."

David Gill, clinical director of the Penn State-Hershey Memory and Cognitive Disorders Program, said certain "non-declarative" memories, like our ability to drive a car or play a piano, become so deeply embedded that we not only don't remember exactly how we learned them, but scientists don't know exactly where in the brain the memories reside.

That is why people with Alzheimer's disease can still remember how to perform some of these basic, strongly wired tasks long after they can no longer remember a spouse's name or who is looking at them in the mirror, Gill said.

If you're still struggling with your checks, there are some mitigating factors to bear in mind.

One is that banks generally don't bounce checks with the wrong date on them, unless the check is one that has a certain time limit. "For example," said Fred Solomon, PNC's vice president of corporate communications, "if a preprinted business check says that it will not be honored after 60 days, and the business owner has dated the check Jan. 20, 2009, (even though it's issued) on Jan. 20, 2010, it may be denied."

Another is that people are writing fewer and fewer checks as online banking has increased.

Finally, the act of check writing itself probably falls into the area of "procedural memories" that are almost automatic, Squire said.

And that means, even if you forget what date it is, you probably won't forget how to write a check.