Personally relevant intrusions outside the laboratory: long-term suppression increases intrusion.

It has been suggested that the suppression of unwanted thoughts may increase their frequency and that this effect may contribute to some psychological problems. Previous studies have examined this over a period of minutes, in an artificial setting. Suppression over a four day period was evaluated in the present study. Each S was asked to identify a negative intrusive thought which he or she experienced and to record each occurrence of it in conditions designed to maximise the similarity to those experienced by obsessional patients. Ss were randomly allocated to one of three groups. One group was asked to suppress their thoughts whenever they occurred, another group was asked to think about their thoughts whenever they occurred and the third group just recorded the thoughts whenever they occurred. This design allowed experimental control of both attention to and manipulation of the target thoughts in contrast to attention and active suppression. It was found that Ss who suppressed their thoughts experienced more thoughts and found them more uncomfortable than Ss in the other two groups. This is consistent with the theory that suppression increases thought frequency and may be important in the development and maintenance of some disorders.