The findings, by lead researcher Michael Anderson, associate professor of psychology at the University of Oregon, and his colleague, John D.E. Gabrieli, professor of psychology at Stanford, will be published Jan. 9 in Science.
The research provides compelling evidence that Freud was on to something 100 years ago when he proposed the existence of a voluntary repression mechanism that pushes unwanted memories out of consciousness. Since then the idea of memory repression has been a vague and highly controversial idea, in part because it has been difficult to imagine how such a process could occur in the brain. Yet, the process may be more commonly applied than was previously thought.
"Often in life we encounter reminders of things we'd rather not think about," Anderson explains. "We have all had that experience at some point-the experience of seeing something that reminds us of an unwanted memory, leading us to wince briefly-but just as quickly to put the recollection out of mind. How do human beings do this?"
Anderson says that this process isn't restricted to traumatic experiences, but is applied widely, whenever we are distracted by memories, pleasant or unpleasant.
"This active forgetting process is a basic mechanism we use to exclude any kind of distracting memory so we can concentrate on our tasks at hand."
To mimic the brain's process in the lab, Anderson and Gabrieli tested subjects using a procedure Anderson devised. Subjects first learned pairs of words such as ordeal-roach, steam-train and jaw-gum. Then they were given the first member of each word pair and asked either to think of the second word, or to suppress awareness of the second word.
Subjects performed t