What This Study Is About

Researchers investigated why it is so difficult to stop thinking about something once you try to suppress it. They used a visual test to see if "suppressed" thoughts actually leave a physical trace in the brain's sensory areas, even when a person thinks they have successfully pushed the thought away.

How They Studied It

The study involved 67 participants who took part in several experiments. Researchers used a technique called binocular rivalry—a visual illusion where a different image is shown to each eye (for example, a red circle to one and a green circle to the other). Usually, the brain flips back and forth between the two.

Participants were asked to either:

Imagine a specific image (like a red apple).

Suppress that image (try not to think about it).

Substitute the image (think of something else, like a white cloud, instead).

Afterward, they viewed the binocular rivalry images. If they had been thinking about "red," they would be more likely to see the red image in the illusion. This allowed researchers to objectively measure the "strength" of a thought without relying only on what the person said.

What They Found

The researchers discovered that trying to suppress a thought is often ineffective. Even when participants reported they had successfully suppressed an image, the visual illusion showed that a "sensory trace" of that image still formed in their brain. In fact, the sensory strength of a suppressed thought was almost as strong as a thought someone was actively trying to imagine.

The study also found that:

Thought substitution (thinking of something else) was much more effective at clearing the mind than pure suppression.

Mindful individuals were better at controlling these mental traces.

Highly anxious individuals had more trouble; for them, suppressed thoughts were sometimes even stronger than thoughts they were trying to imagine.

What This Might Mean

This suggests that "thought-control failure" happens because our brains create involuntary sensory representations of the very things we try to ignore. While this study focused on people with typical imagery, it highlights that mental control is a measurable sensory process. It suggests that for those struggling with intrusive thoughts, simply trying to "not think about it" may be biologically counterproductive, whereas substitution or mindfulness may work better.

One Interesting Detail

The researchers found that even when people were 100% sure they had successfully suppressed a thought and felt they hadn't seen it at all, their eyes and brain told a different story—the "hidden" thought still biased what they saw in the visual illusion.

Research Psychological Science

Measuring Thought-Control Failure: Sensory Mechanisms and Individual Differences

Kwok and colleaguesMay 2019

Read the paper

Abstract
What This Study Is About
How They Studied It
What They Found
What This Might Mean
One Interesting Detail
Authors
Cite this paper

Abstract

The ability to control one’s thoughts is crucial for attention, focus, ideation, and mental well-being. Although there is a long history of research into thought control, the inherent subjectivity of thoughts has made objective examination, and thus mechanistic understanding, difficult. Here, we report a novel method to objectively investigate thought-control success and failure by measuring the sensory strength of visual thoughts using binocular rivalry, a perceptual illusion. Across five experiments ( N = 67), we found that thought-control failure may occur because of the involuntary and antithetical formation of nonreportable sensory representations during attempts at thought suppression but not during thought substitution. Notably, thought control was worse in individuals with high levels of anxiety and schizotypy but more successful in mindful individuals. Overall, our study offers insight into the underlying mechanisms of thought control and suggests that individual differences play an important role in the ability to control thoughts.

Our summary in plain words

What This Study Is About

How They Studied It

Participants were asked to either:

Imagine a specific image (like a red apple).

Suppress that image (try not to think about it).

Substitute the image (think of something else, like a white cloud, instead).

What They Found

The study also found that:

Thought substitution (thinking of something else) was much more effective at clearing the mind than pure suppression.

Mindful individuals were better at controlling these mental traces.

Highly anxious individuals had more trouble; for them, suppressed thoughts were sometimes even stronger than thoughts they were trying to imagine.

What This Might Mean

One Interesting Detail

This summary was written with AI and may contain errors. Check the original paper.

Authors

Eugene L. Kwok
School of Psychology, University of New South Wales
1 paper in the library
Gaelle Leys
School of Psychology, University of New South Wales; Faculty of Psychology and Education Sciences, Katholieke Universiteit Leuven
1 paper in the library
Roger Koenig-Robert
School of Psychology, University of New South Wales
4 papers in the library
Joel Pearson
35 papers in the library

Cite this paper

Kwok, E. L., Leys, G., Koenig-Robert, R., & Pearson, J. (2019). Measuring thought-control failure: sensory mechanisms and individual differences. Psychological Science, 30(6), 811–821. doi:10.1177/0956797619837204

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