'Blocking' negative thoughts may help your mental health, says controversial new study

The new research has been met by scepticism by some scientists.

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Published: September 20, 2023 at 6:00 pm

Have you ever been told to just “try not to think about it”? As frustrating as it might be to hear, bold new research has suggested this might actually be the right advice when it comes to negative thoughts.

In fact, the alternative approach may cause more harm than good, according to the study.

In a University of Cambridge experiment, researchers trained volunteers to suppress thoughts about things that worried them. The results, published in the journal Science Advances, show that the negative concerns became less intrusive and the volunteers’ mental health improved.

“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 behaviour and wellbeing perniciously,” said Professor Michael Anderson, one of the paper’s authors.

Thought avoidance as a coping mechanism for mental health issues (including depression, anxiety and PTSD) was actually scrubbed out of national healthcare guidance in the 1990s. The idea was that if you think and talk about the negative feeling you can deal with it and take its power away.

However, the scientists behind this new research think that thought avoidance should be revisited if we want to control our negative thoughts better.

How did the study work?

So how can you suppress negative thoughts? The researchers say this involves activating a brain mechanism known as ‘inhibitory control’, which gives us the ability to override our reflexive reactions. They discovered that this mechanism can stop our brain from retrieving negative thoughts from our memory.

To test this, they asked 120 volunteers to think of several scenarios that could occur within the next two years. This included negative fears and concerns, positive ‘hopes and dreams’, and also neutral or routine events.

Then the volunteers had to provide a cue word that the researchers could use to remind them of the event. For example, a negative scenario about a health scare had the cue ‘hospital’, while a neutral scenario about an eye test had the cue ‘optician'. A positive scenario where a volunteer’s sister was getting married had the queue ‘wedding’.

Dr Zulkayda Mamat, co-author of the paper, then showed some volunteers the cue for one of their negative scenarios, and some a neutral cue. This took place over Zoom, and volunteers had to stare at the cue word for 20 minutes.

During this time they had to try not to imagine their given scenario – they were asked to not distract themselves with other thoughts, just to simply 'block' images or thoughts related to the event.

In the next phase, Mamat gave some volunteers their cue for a positive personal scenario, and others a neutral cue again. This time, they had to imagine the scenario with as much detail as possible. (The scientists did not make volunteers actively imagine negative events for ethical reasons).

The volunteers then had to rate the vividness of the imagined events before and after the trials. They also answered questions on the level of anxiety and the frequency of intrusive thoughts caused by the event – as well as completing mental health questionnaires.

What was the outcome?

Anderson and Mamat found that the events volunteers tried to suppress became less vivid and less anxiety-inducing. The volunteers also reported improved mental health – both immediately after the trial and three months later.

The researchers saw the biggest change in volunteers who had been given negative – rather than neutral – thoughts to suppress.

Some of the volunteers had existing mental health issues that the technique helped to ease. The volunteers who suffered from PTSD saw their negative mental health scores fall by 16 per cent when they suppressed their negative thoughts.

How seriously should we take this experiment?

Luis Valero Aguayo, Professor of Psychology at the University of Malagá, Spain – a researcher not involved in the experiment – claimed that the study was “well-planned and well-conducted”.

However, Aguayo points out that, especially as it took place online, there is no way of controlling or knowing whether the volunteers were imagining what they were not meant to.

"You cannot ‘keep your mind blank’, as the authors claim," he added. "Simply stating to a person 'don’t imagine the hospital', as the authors say in their example, already gives a stimulus to automatically think of a hospital, even if they don’t want to."


About the expert, Luis Valero Aguayo

Luis Valero Aguayo is a professor of psychology at the University of Malagá, Spain. His research has been published in the European Journal of Behavior Analysis, the journal Psicothema, and in The Practice of Functional Analytic Psychotherapy.


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