Paradoxical effects of thought suppression: A meta-analysis of controlled studies

Research has shown that attempts to suppress a thought ran cause an increas e in the frequency of the thought. These paradoxical effects of though supp ression play a key role in cognitive-behavioral models of several emotional disorders. Laboratory studies of this phenomenon, however, have yielded mi xed results; and narrative summaries of the literature have not been able t o draw from conclusions about the effects of thought suppression. We used m eta-analysis to quantitatively examine the magnitude of thought suppression effects across controlled studies. moreover, we explored whether the varia bility in effect sizes could be explained by methodological differences wit hin and between studies. Results indicated a small to moderate rebound effe ct of thought suppression that varied in magnitude depending on the nature of the target thought and the method Dy which thought frequency was measure d. Participants with clinical diagnoses did not show larger rebound effects than nonclinical or analogue participants, however, only a few studies inc luded clinical samples. Findings are discussed in terms of implications for the ironic process theory of thought suppression, and avenues for future r esearch on this phenomenon. (C) 2001 Elsevier Science Ltd. All rights reser ved.