Intrusive Thoughts: Why Scary Thoughts Don't Define You

You are in the kitchen in the evening, chopping vegetables for the family dinner. Out of nowhere an image flashes through your mind: what if you turned this knife on someone? Your hand freezes. You weren't angry with anyone, and you want nothing of the sort. Yet the image came, your heart is pounding, and one question rises above everything else: what kind of person thinks like this?

If you know some version of this moment, you are not alone, and having the thought does not make you what you fear. Psychology has a name for what just happened: an intrusive thought. Below we look at what it is, what research says about how common it is, why pushing it away tends to backfire, and a five-step tool to try tonight.

What are intrusive thoughts, and why do they feel so dangerous?

An intrusive thought is a thought, image or urge that walks into your mind uninvited and feels foreign to you and to what you value. You didn't plan it and you don't endorse it, but it showed up.

They come in many forms, including:

• images of harming someone you love, or yourself, with no wish to do so;
• endless doubts: did I lock the door, did I make a mistake I can't remember;
• fears of contamination or illness;
• embarrassing scenes in which you imagine saying or doing something wildly out of place;
• sexual thoughts, or thoughts that cut against what you hold sacred.

What they share is the shock. They clash with your picture of yourself, so they frighten you far more than an ordinary stray thought would. The International OCD Foundation notes that most people have unwanted intrusive thoughts from time to time. So the more useful question is not "did I have the thought?" but "how did I read it, and what did I do next?"

Is this normal? What researchers found across six continents

Scientists have been asking this for about half a century. In 1978, Stanley Rachman and Padmal de Silva published "Abnormal and Normal Obsessions" in Behaviour Research and Therapy. They asked ordinary people, not patients seeking treatment, whether unwanted thoughts crossed their minds. A 2015 review reports that 99 of the 124 participants said yes, roughly eight in ten.

An old paper may not convince you, though. Decades later, an international team of 19 researchers, with Adam Radomsky as first author, interviewed 777 university students at 15 sites in 13 countries across six continents. The results appeared in 2014 in the Journal of Obsessive-Compulsive and Related Disorders under a telling title: "You can run but you can't hide."

• 93.6% of participants reported at least one intrusive thought in the previous three months.
• Doubting thoughts were the most common, such as wondering whether you locked the door or made a mistake. Repugnant thoughts, for instance sexual or blasphemous ones, were the least reported, but they did occur.
• The study was designed to widen the lens, because much earlier research had been done in Western or developed countries.

Let's not ask the numbers to say more than they can. The sample was university students, who don't represent everyone, and the question covered the past three months, which relies on memory. Still, the broad picture is clear: a frightening thought crossing your mind doesn't make you a rare case.

Nor does it mean everyone has OCD. The International OCD Foundation estimates that about one in 40 adults in the United States currently has it, so the thoughts themselves are far more widespread than the disorder. What makes a thought pass for most people and stick for a few?

A thought passing through is not a thought you want

The second paper from the same international project had an equally striking title: "They scare because we care." Written by Richard Moulding and colleagues, it analysed interview data from 15 cities and found:

• How often the thoughts occurred, how distressing they were and how easy they were to dismiss differed from site to site.
• Yet the link between those thoughts and how people appraised them and what they did to confront them was similar everywhere. Appraisal and the action taken were among the most consistent predictors.
• Thought content, repugnant or not, changed only how often the thoughts occurred. It did not change how they related to appraisals and control strategies.

These are correlations and don't prove cause on their own, but they fit the cognitive model of OCD: a passing thought does no harm in itself. Trouble starts when you read it as evidence about you and then act on that reading, by analysing, checking, pushing away or avoiding.

Here is a thought that may ease things, offered as a reasonable interpretation rather than a proven result: being horrified by a harmful thought usually signals that it clashes with what you love and value, not that you want it. Don't turn this into a test you rerun on yourself every time. What matters is that it shifts your question from "what does this thought say about me?" to "what will I do now?"

Why pushing it away backfires: the white bear

When a frightening thought barges in, your first move is probably to shove it out: don't think about it, don't think about it. Psychologist Daniel Wegner and colleagues tested that instinct in an experiment published in 1987 in the Journal of Personality and Social Psychology.

Thirty-four university students took part. Each sat alone and said aloud whatever came to mind for five minutes. In one phase they were told to try not to think of a white bear, and to ring a bell on the table whenever they said "white bear" or it came to mind. In the other phase they were told to think about the bear for five minutes. The two groups did the phases in opposite order. There were two findings:

• Suppression failed. Even while trying, participants mentioned the bear or rang the bell more than once a minute on average.
• A rebound followed. Those who suppressed first, when then allowed to think about the bear, mentioned it more than those who were asked to think about it from the start.

In a second experiment in the same paper, people were less preoccupied with the bear afterwards when they were given a specific thing to focus on during suppression. That hints that a clear place to point your attention beats wrestling with emptiness.

Don't treat this as an iron law, though. It used a neutral thought, a white bear nobody fears, in a lab. A 2001 statistical review of many experiments by Abramowitz, Tolin and Street found the rebound effect "small to moderate," depending on the kind of thought and how it was measured. Take it as a warning: pushing a thought away isn't a method to rely on.

When Marcks and Woods tested personal intrusive thoughts in 2005, people told to suppress them could not, and their distress rose. Those taught an acceptance-based approach reported less discomfort, even though their thoughts were no fewer. There is wisdom in that: the aim is not for the thought to vanish, but for its grip on you to loosen so that you can live your day with it present.

In acceptance and commitment therapy (ACT), a thought stuck to you until it feels like fact is called "fusion," and the distance you create from it is called "defusion." Dr. Russ Harris, author of The Happiness Trap, described this skill in training handouts he published in 2007: looking at your thoughts rather than from them. One of his classic exercises is to preface a thought with something like "I notice I'm having the thought that…". He stresses that the aim is not to feel better right away or to get rid of the thought, but to reduce its influence on what you do. The change in wording is small and the change in position is large: from a thought that judges you to a thought you observe.

The "passing guest" tool in five steps

Picture the thought as a guest who knocked on your door without notice. You don't cross-examine them as if they were a suspect, and you don't lean on the door to keep them out. You let them pass through and carry on with what you were doing. This tool comes from the book Resigning from Yourself, and it is shown here in short form.

Go back to the kitchen. The image passes, and you tell yourself: "a passing thought." You don't ask why it came. You keep chopping and keep listening to the people around you. Your chest may flutter for a minute or two, which is understandable. The goal isn't to calm down at once. It is to keep going.

And what if the thought returns twenty times? Each time is a new guest and the steps are the same. Don't count the visits or judge the tool by their number. What you are training is not the end of the visits but what you do when one arrives.

When to see a specialist: signs not to ignore

This tool sits at the heart of Chapter 11, "Guests We Never Invited," in the book "Resigning from Yourself". The chapter presents it through scenes from everyday life and adds a "guest book": three questions to answer honestly so you can see how you treat your own guests. You can read the chapter free, get to know the book on its page, or listen to it in the audio edition.

Tonight, when a thought you never invited passes through, remember that its passing is not a verdict on you. Name it, let it cross, and go back to what is in your hands.