Field of Science

The bright, the dim, and the in-between

Previous research has fairly consistently found a small, but statistically significant, link between religion and intelligence. Non-believers score, on average, a few points higher on IQ tests than believers.

But it's that word 'average' that's the bugbear. Averages don't tell you much about what's actually going on with individuals. What's more, IQ tests are not by any means the full story about intelligence.

Recent research by Sharon Bertsch (University of Pittsburgh) and Bryan Pesta (Cleveland State University), goes some way to putting some fascinating details on the story.

They were interested to know whether the relationship between religion and intelligence is linear, or whether the effects are bunched up at either end of the intelligence spectrum. Maybe being at the high end is linked to non-religion, and the low end to religion, but in the middle - Mr and Mrs Average - there might be no relationship at all between intelligence and religion.

They also wanted to know whether not just abstract reasoning (IQ), but also the ability to process information was linked to religiosity. They did this by testing their ability to rapidly judge the different line lengths, and to pick letter out from a crowd.

They also tested how prone people are to 'overclaim'. This is a fascinating test where people are presented with facts (a famous person's name, a scientific concept, or whatever) and they have to say how familiar they are with it. Some of the facts are false, and using some clever processing they can tease out how much the subjects are overclaiming their familiarity with the real facts.

So how did the subjects do? Well, they studied a bunch of undergraduates, so they were a bit smarter than average and none of them were really dumb. Broadly speaking, they confirmed their suspicions: the bottom quartile was the most religious, the top quartile the least, and that there was not too much difference between the two middle quartiles.

In other words, what we have here is an outlier effect. It's the people on the fringes who are really driving the correlation between intelligence and non-religion.

The effect was strongest for sectarianism - by which they mean the belief that your particular religion is the only true religion. That's the one shown in the figure. But they got similar results for scriptural acceptance and religious questioning (the brightest quartile were least accepting of scriptural truth and the most willing to question beliefs). And they found the same sort of relationship between information processing ability.

So, the question then is what is really driving this effect? Is it IQ, or is it information-processing ability? Well, they found that, when they lumped both in a statistical model, information-processing ability was actually more powerful as a predictor than IQ. In fact, with information-processing ability in the model, IQ became irrelevant.

Now that's a remarkable result. Why on earth should judging line lengths, rapidly selecting letter targets, and accurately rating your own familiarity with real-world concepts be linked to non-religion? The authors suggest that these are indicators of the efficiency of neural processing, which in turn might be a building block for the development of more complex cognition and rational thought.

Only more research will tease that one out - and it should be remembered that this research was done in the psychologists guinea pig - mainly white, mainly Christian, US undergraduates. Does it apply to anyone else? Who knows!

On the plus side, however, this is one of the few studies on intelligence and religion that has involved actual lab research, rather than retrospective analysis of data collected for other reasons. That makes it considerably stronger than most studies into this link - albeit for a fairly narrowly defined representation of the human race!

ResearchBlogging.orgBertsch, S., & Pesta, B. (2009). The Wonderlic Personnel Test and elementary cognitive tasks as predictors of religious sectarianism, scriptural acceptance and religious questioning☆ Intelligence, 37 (3), 231-237 DOI: 10.1016/j.intell.2008.10.003

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


  1. Let me throw another twist into the mix: Why is it that of all the ‘not so bright’ folks out there, only the ones with a religious background made it into college? Any really smart kid can make it into college, but of the marginal ones, why are the religious over represented?

  2. I forgot about this blog. Thanks for covering the work-- I can answer any criticisms or questions you may have.

    Bryan Pesta

  3. Brian,

    Can you shoot me an e-mail with either a link to the paper or some information about your research.

    I'm interested in the link between schizophrenia, which involves impaired information processing, and religiosity. Interested in your research.

    Okiezombies at gmail dot com.
    (yes, that's the informal one for blogger correspondence. I should probably get something more professional sounding). :-)

  4. Reference... darn, I knew I forgot something! Now added to the bottom of the post.

  5. JA Le Fevre - excellent perspective! Religiosity is associated (in the US) with traits such as dutifulness (ie. 'hard working') and social conformism. So it could indeed be that dim people are more likely to make it do college if they are also religious.

  6. A serious study can´t include all spiritualists in the same group.

    There are many religions and many ways of thinking about spirituality.

    As an example: can we, honestly, deny Teresa of Calcutta intelligence?

    More import than Teresa of Calcutta ideas, was her life example coherence with them.

    For Teresa of Calcutta phenomena, science doesn't have an explanation. Why does a strong and intelligent human like her was happy working for the poorest and not for her self? Does natural selection explain this? She was insane?

    Science tell us that universe was created. But can´t explain the reason of universe creation event.

    Exclude any Intelligent Creator, an universe existence first cause, seams me like an illusionist argument, and not a scientific valid argument. Can nothing create something? It's an high IQ evidence think like that?

    Scientists have no obligation of explain the reason why universe exists, but the fact is that universe exists.

    If man´s insignificant work is intelligent (if compared with universe complexity that´s the man physical origin), it's insanity to think that is an Intelligent first cause for creation?

    To explain spiritualists thinking, and create credible statistics evolving them, in first science must know what and why they think. And classify them in categories.

    Superstition is a phenomena, religious or spiritual thinking it's a different phenomena.

  7. As I get time, I can reply to comments below

    Here's a link to my article-- free access for fair use/academic purposes (sixth one down)

  8. Bryan, glad you popped by! Do you have any data on the different ECTs split out? It seems to me that the last one may be functionally different from the other two. Would be interesting to see if there were any indications of a stronger effect on this one.

  9. I love that they teased out both types of mental skills and types of religiousity. This "types of religiousity" is very curious to me. We know there are forms which tolerate high intelligence. Do these folks develop strong abilities to sequester their rational skills? Is it a skill to compartmentalize our lives.

  10. More clued up religious people tend to think of God in general, non-specific terms - and to be more accepting of the idea that other beliefs about god are equally valid.

  11. But some conservative apologists are very bright -- fantastic memories, great rhetoric skills and the ability to tie fallacies together in inscrutable ways.

    They don't have a general god. But I think you are right for the majority. It is those folks I am puzzled about, I guess.

  12. "Superstition is a phenomena, religious or spiritual thinking it's a different phenomena."

    Superstition observes phenomena and relates it to the minds preconceived ideas and imaginative intelligence so as to freeze that which is orthodox, popular and useful in maintaining the orthodoxy.

    "Science tell us that universe was created. But can´t explain the reason of universe creation event."

    Science tells us that what we now experience as human came forth will have its periodicity and will return to what it was.

    Science, the process of observing, noting outcomes and seeking to understand those processes require seeking outside that which is orthodox and tended as fixed.

    Popular superstition seeks to dictate and frowns on seeking outside the confines of the currently popular norm. It will accept ever larger cathedrals, ever more condemning practitioners and teachers of exclusion and ever more compliant cathedral fillers.

    Superstition is compliance to limitation.

  13. I don't really see "religion" being measured against intelligence here. You're taking a very specific brand of religion (fundamentalism) and showing that its adherents aren't very bright. No surprise there.
    What if this same group was asked: "Do you believe in a higher power?" I don't think the differences would be as stark, yet you would still be measuring "religion."

  14. BobO: you're quite right. This study was looking at a particular form of religion, rather than religion in its broadest sense.

  15. Sorry I didn't have more time to interact here.

    Bobo, I agree with you. We measured just variance on a scale of fundamentalism.

    Many scoring low on that scale did believe in a higher power-- we had very few atheists in the sample.


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