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Suppressing negative thoughts may actually be a good thing

The widely accepted notion that suppressing negative thoughts adversely affects our mental health might be incorrect, according to a recent study by scientists at the University of Cambridge. 

The team at the university’s Medical Research Council (MRC) Cognition and Brain Sciences Unit taught 120 volunteers globally how to suppress thoughts about distressing events. The findings revealed that not only did these thoughts become less vivid, but the participants’ mental health also saw an improvement.

Unconscious feelings

“We’re all familiar with the Freudian idea that if we suppress our feelings or thoughts, then these thoughts remain in our unconscious, influencing our behavior and wellbeing perniciously,” said study senior author Michael Anderson, a cognitive psychologist at Cambridge.

“The whole point of psychotherapy is to dredge up these thoughts so one can deal with them and rob them of their power. In more recent years, we’ve been told that suppressing thoughts is intrinsically ineffective and that it actually causes people to think the thought more – it’s the classic idea of ‘Don’t think about a pink elephant.’”

Mental disorders 

Such ideas have become dogma in clinical treatment, with national guidelines arguing that thought avoidance should be considered as a major maladaptive coping mechanism that needs to be overcome and eliminated in mental disorders such as anxiety, depression, or post-traumatic stress disorder (PTSD).

When the COVID-19 pandemic started, Professor Anderson, along with lead author Zulkayda Mamat, who was a PhD student in his lab at that time, were keen to apply their research to help individuals facing anxiety disorders caused by the pandemic. 

Inhibitory control 

Mamat had a particular interest in inhibitory control and its role in overcoming trauma. She was curious whether this could be an inherent ability or an acquired skill.

“Because of the pandemic, we were seeing a need in the community to help people cope with surging anxiety. There was already a mental health crisis, a hidden epidemic of mental health problems, and this was getting worse. So with that backdrop, we decided to see if we could help people cope better,” Mamat explained.

Thought suppression

The researchers brought together 120 individuals from 16 countries to explore the potential benefits of practicing thought suppression. 

In the experiments that the scientists devised, participants were prompted to envision various scenarios that could potentially transpire in their lives within the subsequent two years.

These scenarios included 20 negative scenarios tied to their current “fears and worries,” 20 positive scenarios representing their “hopes and dreams,” and 36 neutral, everyday occurrences. These fears were required to be current concerns, continually infiltrating their thoughts.

Cue words

Each envisioned scenario had to be personally relevant and vividly imagined. Participants assigned a cue word to each scenario (serving as an evident reminder that could be used to evoke the event during training) and identified a key detail (a word encapsulating a central aspect of the event). Some examples include:

Negative: A hospital visit to see parents suffering from COVID-19, with the cue word “Hospital” and the key detail “Breathing.”

Neutral: An appointment at the opticians, cue word – “Optician,” key detail – “Cambridge.”

Positive: Witnessing one’s sister’s wedding, cue word – “Wedding,” key detail – “Dress.”

Participants rated each scenario based on several factors, including vividness, probability of occurrence, temporal distance, emotional intensity, and level of anxiety or joy. 

Additionally, they completed mental health questionnaires. No exclusions were made in order to ensure a diverse participant pool, encompassing individuals with serious depression, anxiety, and pandemic-induced PTSD.

Training sessions

Subsequently, Mamat conducted a 20-minute training session for each participant via Zoom. The training, spanning three days, consisted of 12 ‘No-imagine’ and 12 ‘Imagine’ repetitions for the scenarios.

During the No-imagine trials, participants, upon receiving one of their cue words, acknowledged the associated event mentally. 

Blocking negative events

Maintaining focus on the reminder cue, they endeavored to cease any contemplation of the event, neither imagining it nor using divergent thoughts as a distraction, but attempting to block any arising thoughts or images. In this phase, negative events were assigned to one group for suppression, while neutral events were assigned to another.

Imagine trials

In contrast, during the Imagine trials, participants, equipped with a cue word, were instructed to vividly imagine the scenario, contemplating the potential feelings associated with it. Due to ethical reasons, participants were only assigned positive or neutral scenarios to imagine, not negative ones.


Following the final training day and again three months thereafter, participants reassessed each scenario’s vividness, anxiety level, and emotional intensity, and refilled the mental health questionnaires to measure alterations in depression, anxiety, worry, affect, and overall wellbeing – all pivotal aspects of mental health.

What the researchers learned 

“It was very clear that those events that participants practiced suppressing were less vivid, less emotionally anxiety-inducing, than the other events and that overall, participants improved in terms of their mental health,” Mamat reported. The most significant improvement was seen among participants who practiced suppressing negative thoughts.

Post-training evaluations revealed that the suppressed events were less vivid and induced less fear. Moreover, a substantial improvement in mental health was noted, especially among participants with likely PTSD who suppressed negative thoughts.

Challenging assumptions

This discovery challenges the prevailing idea that suppression is an inadequate coping mechanism. The research found no evidence of a ‘rebound’ effect, where suppressed thoughts become more vivid. 

“What we found runs counter to the accepted narrative,” Professor Anderson emphasized. He added that while additional research is needed, active suppression of fearful thoughts could be potentially beneficial.

Lasting mental health benefits 

Even though the continuation of the technique wasn’t mandated, many participants opted to keep practicing it. Mamat discovered that the benefits, particularly the reduced levels of depression and negative emotions, persisted for all, especially for those who integrated the technique into their daily lives.

“The follow up was my favorite time of my entire PhD, because every day was just joyful,” Mamat said. “I didn’t have a single participant who told me ‘Oh, I feel bad’ or ‘This was useless.’ I didn’t prompt them or ask ‘Did you find this helpful?’ They were just automatically telling me how helpful they found it.”

One of the participants was so impressed by this method that she thought her mother and daughter how to use it. Another told Mamat that she had moved to another place just before the beginning of the pandemic and felt very isolated.

“She said this study had come exactly at the time she needed it because she was having all these negative thoughts, all these worries and anxiety about the future, and this really, really helped her. My heart literally just melted, I could feel goosebumps all over me. I said to her ‘If everyone else hated this experiment, I would not care because of how much this benefited you!,’” Mamat concluded.

The study is published in the journal Science Advances.

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