Sometimes we're more likely to remember words that we were instructed to forget, while being more likely to forget words that we were instructed to remember. How can this be?
Fifty-six students were presented with four words from two different categories, (e.g. flower: lily; country: Russia; flower: tulip; country: Sweden). Crucially, half the students were told to remember these words, whereas the other students were told to forget them.
Next the students were asked to generate four novel examples from one of the previous categories (e.g. Flowers). To help, they were given the first two letters of a new example (e.g. Pa_ for pansy).
This whole process was repeated several times with different starting word pairings and categories. After a five-minute irrelevant distractor task, there was a final big recall test, in which the students were asked to recall as many of the original word pairings as possible. As you'd expect, overall, the students told to remember the original word pairings, did indeed remember more of them. But there is a twist.
For the students told to remember the original word pairings, generating novel word examples for a given category caused them to forget original words belonging to that same category. (They remembered 16 per cent fewer original words from categories for which new examples had to be generated). By contrast, the students told to forget the original words were not affected in this way.
The net result is that compared to the students told to remember, the students told to forget the initial word pairings actually remembered slightly more of the original words from categories for which new examples had to be generated.
A possible explanation is the students told to remember the original words, had mentally to inhibit these words when it came to generating fresh examples for a given category. This inhibition process affected their memory for these original words. By contrast, it seems students told to forget the original words didn't need to inhibit them during the word generation task – in a sense the original words had been protected from the inhibition process, making them more likely to be remembered later.
“Ironically, therefore, whereas the intention to remember may lead one to forget, the intention to forget, may lead one to remember,” the researchers said.
Storm, B.C., Bjork, E.L. & Bjork, R.A. (2007). When intended remembering leads to unintended forgetting. The Quarterly Journal of Experimental Psychology, 60, 909-915.
Link to new research taking a biological approach to this idea.