Paradoxical effects of thought suppression.
Journal of personality and social psychology July 1, 1987 D M Wegner, D J Schneider, S R Carter et al.
Attempting to suppress a thought can make it more likely to return, a phenomenon known as the ironic process theory. In two experiments, people asked not to think of a white bear for five minutes were unable to do so, ringing a bell each time the thought occurred. After the suppression period, they reported significantly more thoughts about the white bear than people who were simply asked to think about it from the start. Providing a specific distracting thought during suppression reduced this later preoccupation. The findings suggest that thought suppression can backfire as a self-control strategy, potentially intensifying the very obsession it aims to eliminate.