Mimicking memory repression

Whether or not we can choose to lose memories has been a controversial question since Freud claimed that we can repress unwanted memories by pushing them into the unconscious. Repression is often associated with post-traumatic stress, making it difficult to study in the laboratory because of ethical and practical reasons. In the 15 March Nature, Michael Anderson and Collin Green of the University of Oregon, report a method for mimicking memory repression in the laboratory (Nature 2001, 410:366-369).

Anderson and Green trained human volunteers on 40 unrelated word pairs (for example, ordeal–roach) so that they could provide the right-hand member of each word pair when shown the left-hand member. Next, the subjects had to exert conscious control over the retrieval process in a 'think/no-think' trial. Depending on which word appeared on a computer screen, subjects were told to either recall and say the associated response word...