Ever since Freud first suggested that people could suppress memories, psychologists have been arguing about whether and how people might accomplish the task. Can people intentionally repress traumatic memories? Now, a simple study shows that people can purposely forget something they just learned. These results pave the way for a better understanding of how people remember--or forget--emotionally charged experiences.
The cognitive neuroscientists who conducted the new study were inspired by research on child abuse. Adults who were abused as children by someone they knew, studies show, were more likely to forget about the abuse than adults who were abused as children by a stranger. The researchers, Michael Anderson and Collin Green of the University of Oregon, Eugene, wondered if having to confront the painful memories on a daily basis would cause the children to try to forget. So they devised a word-based experiment to test this idea.
The test, dubbed "think/no-think," required a lot of remembering--and remembering to forget. First, 112 college students memorized 40 pairs of unrelated words. Then the researchers directed them to prepare to suppress a subset of the word pairs, the "no-think" subset. Next, the subjects watched as a computer screen flashed up the first word from each pair. The subjects had to either say the matching member of the pair or, if the word came from a "no-think" pair, they had to try to not think about the matching word. After repeating this step up to 16 times, the researchers tested the subjects' memory for all word pairs.
The more rounds in which the subjects had tried to not think about the response word, the more likely they were to have forgotten it, even when prompted with an extra clue such as the first letter, the researchers report in the 15 March issue of Nature. People forgot about 12% more of the response words in the "no-think" list than they did from the "to remember" pairs, even when offered money at the end of the experiment to remember them.
Anderson ties this research to the child abuse literature by pointing out that "this shows that you don't need an emotional motivation, you just need the intention to keep the memory out of your mind." Cognitive neuroscientist Daniel Schacter of Harvard University says that the study is important and well-controlled, but he cautions that forgetting words "doesn't address the issue of whether an emotional experience can be suppressed. That's an open question."