Do sceptics have more inhibitory brain control than supernatural believers?

Imagine your partner has just been arrested for drink driving. You're walking down the street not long after and suddenly you see a large poster of a brick wall. Is it a sign? A new study suggests your interpretation of that poster depends on the levels of inhibitory activity in a part of your brain. Marjaana Lindeman and her colleagues propose that it's human nature to read meaning into arbitrary symbols, but that sceptically minded people are able to ignore or suppress this instinct whereas supernatural believers are not.

Twenty-three volunteers had their brains scanned while they imagined a series of various scenarios and viewed a picture after each one. In all cases they were to imagine they were walking down the street after the scenario had unfolded and the picture was seen on a poster. Another example was wondering if they were going to get a pay rise and then seeing a poster of a pair of jeans. For each picture, the participants stated whether, in the hypothetical context, they would consider that it contained a sign or a message.

The participants had been pre-screened so that half of them were supernatural believers (they agreed with statements like "some psychics can accurately predict the future") and half were sceptics. As you'd expect, the supernatural believers saw meaning in the images twice as often as the sceptics. Another key difference was that sceptics exhibited more activity in their right inferior frontal gyrus (IFG) when viewing the images – this is a region of the brain that past research has suggested is involved in cognitive inhibition.

We need to be cautious before assuming that the IFG played an inhibitory role in this study. However, such an interpretation is consistent with past research showing that sceptics outperform believers on tests of inhibitory control. Moreover, across both groups in the current study, more IFG activity was associated with reduced belief that the pictures contained signs.

"Cognitive inhibition, that is, suppressing or overriding spontaneously occurring mental processes, may thus be the mechanism that, when working efficiently, controls our natural intuitions and explains why supernatural interpretations seem so natural for some and yet others find them quite strange," the researchers concluded.

This brain research is consistent with past evidence supporting the idea that supernatural beliefs are instinctual and take effort to be overcome. For example, a 2012 study found that physics professors endorse quasi-religious explanations for natural phenomena when they're put under time pressure.

A weakness of the current research, acknowledged by the authors, is that the sceptics and believers may have differed on other relevant factors. For instance, perhaps the believers were more creative and it's this trait that was associated with their ratings of the pictures and their brain activity.

Further reading

Marjaana Lindeman, Annika M. Svedholm, Tapani Riekki, Tuukka Raij, and Riitta Hari (2013). Is it just a brick wall or a sign from the universe? An fMRI study of supernatural believers and skeptics. Social Cognitive and Affective Neuroscience DOI: 10.1093/scan/nss096