Field of Science

Most people are a bit crazy, and believers are a bit crazier than most

Full-blown delusions are thought to be pretty rare. By that I mean the truly bizarre delusions, like Capgras syndrome (when you think that relatives or close friends are sometimes replaced by identical-looking impostors), or Subjective Doubles (a belief that there is another person who looks and acts like you) and Controlled Thoughts (that your thoughts are not fully under your control).

It's actually quite difficult to find out just how common these kinds of delusions are. You can't just ask people a straight question, because there's a good chance that they won't give you a straight answer (nobody wants to seem to be a lunatic).

So Rachel Pechey and Peter Halligan, at Cardiff University in Wales, created a new questionnaire specifically to try to find out how common bizarre delusions actually are. They did this by asking about symptoms without framing them in terms of mental illness, and by asking about them as part of a larger questionnaire covering all kinds of beliefs - including religious and political beliefs.

They interviewed 1,000 people from around Britain, and found that a staggering 78% of them said that they currently experienced one or more bizarre delusions to some degree. Some 26% reported a 'strong' experience of a bizarre delusion.

So, for example, when asked "Do you believe that people you know disguise themselves as others to manipulate or influence you?", 4.4% said that they strongly believe' this to be true.

They also asked about a range of paranormal and religious beliefs - and you can see the results in the figure below.

Just over 25% were atheists, but of course some of them might have held one of the other kinds of paranormal beliefs. Hopefully there were no atheists among the 5% of the population who believe in werewolves!

Then they looked at how these paranormal and religious beliefs correlated with the delusional beliefs (to do this, they excluded the werewolf and astrology questions - because they didn't form part of a common statistical factor along with the other paranormal/religious beliefs).

Well, you probably know where this is heading. There was a good correlation between paranormal/religious beliefs and delusional beliefs. In contrast, there was no correlation between either of these and a third basket of questions relating to political and social beliefs.

This fits with other research, showing that delusional beliefs are more common among the religious and among 'New-Age believers' (see When people stop believing in God... they go mental?). Halligan points that delusional beliefs don't seem to result in as much distress among these populations, and that fits with other evidence that psychotic patients with religious beliefs are less distressed (see Why psychotic patients with religious delusions are harder to cure).

Just why there should be this correlation is harder to say. Certainly, if you've had some freaky experiences, then it stands to reason that you're going to be more open to unorthodox ideas about how the world works.

But Halligan suggests that there may be a deeper connection:

One potential explanation is that holding a belief may impact upon an individual’s wider belief system so that the endorsement of similar (e.g. irrational/unscientific) beliefs becomes more likely. This is in line with the web-of-belief hypothesis advocated by Quine and Ullian, which suggests that a belief coheres with other beliefs held by an individual. In addition, other cognitive factors such as the reasoning biases associated with delusions may also play a role in the development of other abnormal beliefs.

In other words, religion and delusional beliefs may form part of a reinforcing worldview, and both may also be prompted by failures of rational thought. Other research has pointed in a similar direction (see You either believe it all... or you don't).

ResearchBlogging.orgPechey R, & Halligan P (2011). The Prevalence of Delusion-Like Beliefs Relative to Sociocultural Beliefs in the General Population. Psychopathology, 44 (2), 106-115 PMID: 21196811

Creative Commons License This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.


  1. Controlled Thoughts (that your thoughts are not fully under your control).

    I believe that! To me, people who think their thoughts are fully under their control are totally deluded. I'm not even sure what it even means even that there is an "I" that even controls the thoughts of the mind, even.

  2. Be careful, or they might come to take you away! I know what you mean, though, although I think that most people usually feel that they are in control of their thoughts. Like it feels like we have free will - even though that might be meaningless from a biological/philosophical perspective.

    In fact, the feeling that your thoughts are not your own is a classic symptom of schizophrenia.

    Anyway, you will be happy to know that 33.6% said that they do not feel fully in control of their thoughts - 13% held that belief weakly, 15.1% moderately, and 6.2% strongly.

  3. What's really remarkable here is that more people believe in possession by evil spirits/demons than believe in the spirits/demons themselves.

  4. You know, a couple of those propositions are relatively untestable, and so cannot in any sense be called delusional.

    Specifically the god, soul and reincarnation statements are not amenable to testing (in any way i can imagine), and many of the others are extremeley difficult to prove wrong: i.e. werewolves, posession as to do so would require more data than we currently possess.

    So, in that sense, while you may not believe those statements (i dont believe most of them), we cannot say that they are delusional with any kind of scientific authority,as we do not possess data which would allow us to make those claims.

  5. When I started my blog I centered on Atheism and, being new to blogging, started discovering all the atheist sites out there and quickly saw a problem. Most of the atheist, or at least the blogging atheists, were non-sympathetic to weird experiences. Almost so that they thought that people who had them were, by definition, crazy.

    Well, I have had lots of weird experiences and so I built a list of them to show other atheists that even non-crazy, non-fanatic atheists can have very odd experiences. [Ok, sure, I am assuming I am not crazy, big assumption, I know.]

    Yet contrary to your emphasis (I think) my weird experiences came even though I had no religious predisposition towards them -- I didn't "believe" weird things, I just experienced them even when I was an atheist. But, as you say, it may have made me more susceptible to broader explanations.

    So my suspicion is that the disposition comes first (in ?most/many/some) cases. Must time is wasted in Atheist debate which sees such experience as a consequence of wrong belief. It seems many atheists (especially "Natural Atheist") live a poverty stricken mental life --- well, "poverty stricken" from this sickos perspective. And indeed, ironically, these poverty-stricken atheists are likewise closed to understanding the spectrum of mind -- they were only interested in their own tunnel vision.

  6. Disgruntled PhD, please... Russell's teapot? Would that be a delusional belief? Strictly speaking, you cannot say!

    On the post itself -- FWIW there probably are some werewolf-believing atheists. No matter what demographic factors you apply, a certain percentage of people will always be idiots.

    Regarding Bjorn's comment -- I think the implication is that there is some external force controlling one's thoughts. That's how I would have read the question, and I would have put down that I never experienced it. If in the context you are interpreting it, of course I would have to say I am not...

  7. Disgruntled PhD: the questions about god soul and reincarnation are all from the 'Paranormal/religious beliefs' set, not from the 'delusional beliefs' set of questions. The point is not that these beliefs are delusional per se, but that they are more common in people who also have delusional beliefs.

  8. Sabio, no I agree with you. I think that the delusional beliefs come first and (depending on your particular cultural environment) they lead to paranormal/religious beliefs.

  9. Just what, after all, do we Know? Our brains have a long neural connection to sensors to the outside, but a very short path to its own dreams and imagination. Even birds have ‘REM sleep’, and what we know of dreaming, it is a very important aspect of our mental process. Additionally, a wide range of diet/drugs, health and stress conditions impact our neural performance. Mild toxins in the food supply (molds and etc.), electrolyte imbalance from dehydration or diarrhea, various traumatic stresses – all varieties of environmental stresses challenge our ability to monitor our own mental processes – to distinguish dreams from external stimuli, our ‘real’ from our ‘imaginary’ friends. Look at the ‘climate’ that fosters atheist conversion: very low ‘diet’ stress, low social stresses. While these conditions may be desirable, they are unusual in the broad human experience.

  10. Thanks for the post Tom. This hit especially close to home for me, given that one side of my family has a strong tendency towards delusions of the clinical variety, and their delusions are entirely consonant with their religious views. It is as if the two go hand in hand, and one justifies the other. It makes for exceptionally awkward interactions, and is painful to watch because they will not seek help, and do not think anything is wrong.

  11. Disgruntled PhD: the questions about god soul and reincarnation are all from the 'Paranormal/religious beliefs' set, not from the 'delusional beliefs' set of questions. The point is not that these beliefs are delusional per se, but that they are more common in people who also have delusional beliefs

    Bit late back to the party, but how (in any real sense) are these different?

    They are all relatively untestable ideas that either very few ("delusions") or very many ("paranormal") ideas which people believe. From your perspective (atheistic), how are they different?

    Again, i'm not saying i believe any of them, but i am pointing out the silliness of grouping them differently.

    In any case, DSM would suggest that delusions of any kind are not an issue unless it causes you to be unable to function in society. Whether or not that is a good definition, its the most "scientific" definition we have of delusions.

    Great blog by the way, i almost always interpret things differently from you, but you've pointed me towards some useful information.

  12. Well, we all have a bunch of untestable beliefs. Like you say, what DSM-IV is interested in is a practical issue. How can you identify people who might benefit from psychiatric help? SO they zero in on the uncommon, 'bizarre' beliefs.

    So in this study they tested three different kinds of untestable beliefs - bizarre, religious/paranormal, and political/social. What this suggests is that all strongly held, untestable beliefs are not the same.

    Glad you like the blog :) The best thing about comments is getting different perspectives on the same data!

  13. A direct causal arrow to/from religion would be very surprising. Feedback loops less so. Genetics less still.

    Note, education gives us tools for how to think. It doesn't tell us what to think/believe. The educated may turn out to be just as likely to hold a mystical belief, and yet more inclined to identify their personal belief as a claim about reality that can be evaluated. As per Sean, those examining their religious beliefs in the same way as their other beliefs tend towards deism, agnosticism, personalised spirituality, etc.

  14. I just had to chime in here. Disgruntled PhD suggests that untestable beliefs can not be called delusional.

    Is it not perfectly obvious that all untestable beliefs must be delusions?

    I believe in the teapot in orbit around Mars, prove me wrong. I believe in the invisible pink unicorn, prove me wrong. I believe in Jesus, prove me wrong. It is exactly the same thing.

  15. I question the material as presented based on the authors obvious bias:
    "Hopefully there were no atheists among the 5% of the population who believe in werewolves!"
    Also Given the statement that:
    "Some 26% reported a 'strong' experience of a bizarre delusion."
    I suspect the questionnaire was flawed. Since this appears like a contradiction to me it may very well have been unclear to the respondents.

    Thank you for the article.

  16. delusion is when you have a false belief that persists despite compelling contradictory evidence. Delusions are bizarre and far-fetched notions. I don't know how you could ask people if they have had crazy delusions, because people who do don't think they are delusions. They are mentally ill and in most cases have schizophrenia. The people aren't crazy, they have a disease. They can't help it. They are really just like anyone else, they just need help controlling the things they do.


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS