Why is it hard to "unlearn" an incorrect fact?

Cognitive psychologist Gordon H. Bower of Stanford University answers

By The Editors

Why is it that once you learn something incorrectly (say, 7 X 9 = 65), it seems you never can correct your recall?
—J. Kruger, Cherry Hill, N.J.

Cognitive psychologist Gordon H. Bower of Stanford University answers:

Identifying, correcting and averting our memory errors are part of a cognitive process called memory monitoring. Incorrect associations can be tough to change, but we can use techniques to retrain our brain.

When strong habits impede our ability to acquire a desired new habit or association, we experience a common phenomenon known as proactive interference. Wrong associations appear in common spelling errors such as “wierd” for “weird” and “neice” for “niece.” Persistent mistaken connections also can cause embarrassing errors, such as calling a man’s second wife by the name of his first. Interference is stronger the more previous wives you’ve had to deal with, and it is more difficult to overcome the stronger the habits are.

Accurate memory monitoring requires a well-functioning prefrontal cortex (PFC). Young children, who have an immature PFC, and stroke patients with extensive PFC damage make more errors as a result of memory-monitoring failures. They are more likely to confuse the source of information they recall, and they are more susceptible to accepting as true an event they only imagined.

You can overcome proactive interference by consistent (even silent) correction, especially when you space rehearsals over time. But it takes some conscious practice. We have to identify (or be told) when we have just made an error so that we can correct it immediately. Our inability to do so is typically the cause of the error’s persistence.

Building on the correct information can help you learn new associations to it: add something to change how you retrieve the item from your memory. You might replace your question “Name of John’s wife?” with “Name of John’s second wife?”; or use an elaboration that contains the accurate information, such as “We are weird” or “My niece is nice”; or convert 7 X 9 into 7 X (10 – 1) = 70 – 7 = 63. As you practice the elaborated association, the simpler direct association (7 X 9 = 63) eventually replaces the earlier one, which weakens without rehearsals. Labeling and rehearsing the wrong association (for example, saying to yourself, “7 X 9 is not 63”), however, are distinctly counterproductive.