Simon Nørby and his colleagues at the University of Copenhagen presented dozens of undergrad participants with word pairs, each made up of a cue word and an unrelated target word. Past research has suggested that people are able to deliberately forget some target words while remembering others. But this has been over very short time periods. Nørby's team wanted to test the effects of deliberate forgetting over a longer time period - a week - and they also wanted to revisit the question of whether emotional words can be deliberately forgotten as easily, or more easily, than neutral words. Past research has suggested they can, but these studies have tended to block emotional word pairs altogether in series of themed trials, thus raising the possibility that their impact may have been diminished by habituation. Nørby's team avoided this problem by jumbling up neutral and emotional words altogether.
The participants spent time learning 70 word pairs, then they were informed which target words were to be deliberately forgotten and which to be retained. An ensuing training process helped them with this. Participants repeatedly gave the target words when presented with cues for to-be-remembered pairs (if they couldn't remember it, they were told the target word), whereas they repeatedly withheld and attempted to suppress target words when presented with the cues for to-be-forgotten pairs. After all this, the participants were tested once again on all the word pairs, with their task to recall even those they had deliberately forgotten.
The results of this immediate test suggested that the participants had succeeded, to some extent, in deliberately forgetting those neutral words that they were supposed to forget. Recall for to-be-forgotten neutral words dropped from a baseline of about 80 per cent to about 70 per cent, whereas accurate recall for to-be-remembered words had increased to 95 per cent (unsurprisingly, the final training phase had acted as memory aid for these words). By contrast, suppressed, to-be-forgotten negative emotional words like 'massacre' and 'incest' remained unforgotten and were recalled just as accurately as to-be-remembered emotional words.
On retesting a week later, to-be-forgotten emotional and neutral words were recalled just as often as to-be-remembered words. In fact, over the course of a week, there was evidence that memory for to-be-forgotten words had deteriorated less than memory for to-be-remembered words. This could be another manifestation of the ironic 'suppression rebound effect' which is the finding that deliberately suppressing certain thoughts can make them come back stronger.
Taken altogether, the results suggest that neutral material can be deliberately suppressed over short time periods, but not for as long as a week. Negatively emotional material, by contrast, appears to be stubbornly resistant to deliberate suppression. This flies in the face of the psychoanalytic idea of repression, but is consistent with trauma research suggesting that emotionally salient memories are more persistent than normal, not less.
Nørby S, Lange M, & Larsen A (2010). Forgetting to forget: on the duration of voluntary suppression of neutral and emotional memories. Acta psychologica, 133 (1), 73-80 PMID: 19906363
Image credit: fancy
Previously on the Digest:
Can we deliberately forget specific parts of what we've read?
How remembering can lead to forgetting.
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