Psychotherapy and Neuroscience

Thought Suppression

Retrieving traumatic memory is disturbing in its reexperiencing of painful sensory components, negative emotion, negative appraisals of self in interaction, and unpleasant bodily sensations. According to an interpretation of William James’s model (1983), survivors can avoid reexperiencing unpleasant memory by forcing out reminders and forgetting about them. Accordingly selectively attending to items of greater interest and goal relevance and ignoring goal-irrelevant unpleasant memory reminders facilitates a sense of well-being and relief from the latter (Ochsner & Gross, 2005). Trauma survivors don’t explicitly think to themselves “I don’t want to think about it” (Kihlstrom, 2002). They avert reexperiencing fear and implicitly avoid rethinking about the traumatic experience (Bryant & Harvey, 1996). They also divert their attention and reattend to more pleasant thoughts. Processes of avoidance-inhibition-attentional redirection supporting thought suppression are also supported by senses of motivational relief and of well-being that are associated with traumatic pain avoidance (McClelland, 1985).

Thought suppression empirically has been shown to impair memory coherence. Thought suppression during and immediately after a film has been shown to impair the subsequent retrieval of properly sequenced film narrative memory, to reduce its coherency, produce “snapshots” of events and increase thought preoccupation (Wegner, Bjork, & Eich, 1994; Wegner, Quillian, & Houston, 1996). Moreover researchers have been developing neuroimaging event related studies that seek to monitor and specify thought processes that would normally be inaccessible for study. Anderson and researchers (Anderson & Green, 2001; Anderson, Ochsner, Kuhl, Cooper, Robertson, Gabrieli et al., 2004) adapted a retrieval induced forgetting paradigm, the “think/no-think” paradigm in their study of thought suppression. After subjects learned word pairs they were instructed either to think about and recall a given word pair or suppress and prevent the associated word pair from entering consciousness while being scanned. Subjects, who were instructed to retrieve practiced items after learning, had better memory for practiced words. Subjects, who tried to stop the retrieval of words in the post-learning suppression condition, experienced far greater recall impairments (Levy & Anderson, 2002). During the suppression condition midcingulate cortex (BA32) was active during task-related activity. The bilateral dorsal-ventrolateral prefrontal cortices (BA 45/46) were active during the suppression condition and keeping information out of mind (Bunge, Ochsner, Desmond, Glover, & Gabrieli, 2001). The act of suppressing word pairs also concurrently reduced hippocampal activity as well as another anterior prefrontal area that is typically involved in remote memory retrieval, the frontal polar cortex (BA 10). Reduced hippocampal activation reflected successful blocking from mind of unwanted task-dependent thought processes (Anderson et al., 2004). In another neuroimaging study, activations in both midcingulate cortex and dlPFC were associated with weak retrieval of test items; hippocampal activity was associated with strong retrieval (Bunge, Burrows, & Wagner, 2004). These findings have also been supported by others that also note the monitoring of decisions and response inhibition involves the midcingulate cortex and dorsal and ventrolateral PFC respectively (de Zubicaray, Zelaya, Andrew, Williams, & Bullmore, 2000; Liddle, Kiehl, & Smith, 2001; Menon, Adleman, White, Glover, & Reiss, 2001). Therefore, increased activation in midcingulate cortex and bilateral dorsolateral PFC (BA 9/46) with reduced hippocampal activity has predicted later impaired memory for chosen items.

The above findings are also supported by lesioning and stimulation studies. A human lesioning study (Conway & Fthenaki, 2003) found that patients with lesions of the frontal cortex (allowing expression of the hippocampal region’s retrieval capabilities) were impaired on directed forgetting tasks, i.e. patients could not stop or control the tendency for remembering that which needed to be forgotten. Temporal patients with MTL lesions (allowing expression of the prefrontal inhibitory capabilities over retrieval) were significantly impaired at recalling required information. In contrast repetitive transcranial magnetic stimulation (rTMS) of the right dlPFC (which tends to enhance this region’s function) tends to interfere with deliberate recognition and retrieval of newly learned task-related visuospatial memory (Rossi, Miniussi, Pasqualetti, Babiloni, Rossini, & Cappa, 2004). These findings support a role for the dorsolateral prefrontal cortex in inhibiting retrieval.

Prefrontal inhibitory activity and suppressive processes over time may limit retrieval induced cue driven reactivation and this may inhibit consolidation processes and hippocampal mediated encoding into cortical long term retrieval regions. Synergistic activity between both the cortex and hippocampus is necessary for later explicit remote memory recall (Wittenberg & Tsien, 2002). Suppressive processes may not only serve to strengthen lateral prefrontal inhibitory mechanisms over time due to continual use but also concomitantly inhibit and weaken retrieval of a specific memory (Levy & Anderson, 2002). Using these adaptive processes over time may make certain memory, like traumatic narrative memory, more and more inaccessible.


Anderson, M.C., & Green, C. (2001). Suppressing unwanted memories by executive control. Nature, 410(6826), 366-369.

Anderson, M.C., Ochsner, K.N., Kuhl, B., Cooper, J., Robertson, E., Gabrieli, S.W., Glover, G.H., & Gabrieli, J.D. (2004). Neural systems underlying the suppression of unwanted memories. Science, 303(5655), 232-235.

Bryant, R.A., & Harvey, A.G. (1996). Initial posttraumatic stress responses following motor vehicle accidents. Journal of Traumatic Stress, 9(2), 223-234.

Bunge, A.S., Burrows, B., & Wagner, A.D. (2004). Prefrontal and hippocampal contributions to visual associative recognition: interactions between cognitive control and episodic retrieval. Brain and Cognition, 56(2), 141-152.

Bunge, S.A., Ochsner, K.N., Desmond, J.E., Glover, G.H., & Gabrieli, J.D. (2001). Prefrontal regions involved in keeping information in and out of mind. Brain, 124(10), 2074-2086.

Conway, M.A., & Fthenaki, A. (2003). Disruption of inhibitory control of memory following lesions to the frontal and temporal lobes. Cortex, 39(4-5), 667-86.

De Zubicaray, G.I., Zelaya, F.O., Andrew, C., Williams, S.C., & Bullmore, E.T. (2000). Cerebral regions associated with verbal response inhibition, suppression, and strategy use. Neuropsychologia, 38(9), 1292-1304.

James, W. (1983). The principles of psychology. Cambridge, MA.: Harvard University Press. (Chapters 9, 11, and 16)

Kihlstrom, J.F. (2002). No need for repression. Trends in Cognitive Sciences, 6(12), 502.

Levy, B.J., & Anderson, M.C. (2002). Inhibitory processes and the control of memory retrieval. Trends in Cognitive Sciences, 6(7), 299-305.

Liddle, P.F., Kiehl, K.A., & Smith, A.M. (2001). Event-related fMRI study of response inhibition. Human Brain Mapping, 12(2), 100-109.

McClelland, D.C. (1985). Human motivation. Glenview, Illinois: Scott, Foresman, & Co. (Chapters 7, 8, 9, 10).

Menon, V., Adleman, N.E., White, C.D., Glover, G.H., & Reiss, A.L. (2001). Error-related brain activation during a Go/NoGo response inhibition task. Human Brain Mapping, 12(3), 131-43.

Ochsner, K.N., & Gross, J.J. (2005). The cognitive control of emotion. Trends in Cognitive Sciences, 9(5), 242-249.

Rossi, S., Miniussi, C., Pasqualetti, P., Babiloni, C., Rossini, P.M., & Cappa, S.F. (2004). Age-related functional changes of prefrontal cortex in long-term memory: a repetitive transcranial magnetic stimulation study. Journal of Neuroscience, 24(36), 7939-7944.

Wegner, D.M., Bjork, R.A., & Eich, E. (1994). Thought Suppression. In: D. Druckman & R.A. Bjork. Learning, Remembering, Believing, pp. 277-293, Washington D.C.: National Academy Press.

Wegner, D.M., Quillian, F., & Houston, C.E. (1996). Memories out of order: thought suppression and the disturbance of sequence memory. Journal of Personality and Social Psychology, 71(4), 680-691.

Wittenberg, G.M., & Tsien, J.Z. (2002). An emerging molecular and cellular framework for memory processing by the hippocampus. Trends in Neurosciences, 25(10), 501-5.