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The Biology of Belief

UPDATE: Project Reason is currently preparing to run another neuroimaging study on belief. Our goal will be to discover which regions of the brain allow people to change their beliefs, or prevent them from doing so, in response to new evidence.

Sam Harris, Jonas T. Kaplan, and colleagues have published the first study to compare religious faith to ordinary belief at the level of the brain. This neuroimaging research was funded, in part, by a grant from Project Reason.




While religious faith remains one of the most significant features of human life, little is known about its relationship to ordinary belief at the level of the brain. Nor is it known whether religious believers and nonbelievers differ in how they evaluate statements of fact. Our lab previously has used functional neuroimaging to study belief as a general mode of cognition [1], and others have looked specifically at religious belief [2]. However, no research has compared these two states of mind directly.

Methodology/Principal Findings

We used functional magnetic resonance imaging (fMRI) to measure signal changes in the brains of thirty subjects—fifteen committed Christians and fifteen nonbelievers—as they evaluated the truth and falsity of religious and nonreligious propositions. For both groups, and in both categories of stimuli, belief (judgments of “true” vs judgments of “false”) was associated with greater signal in the ventromedial prefrontal cortex, an area important for self-representation [3], [4], [5], [6], emotional associations [7], reward [8], [9], [10], and goal-driven behavior [11]. This region showed greater signal whether subjects believed statements about God, the Virgin Birth, etc. or statements about ordinary facts. A comparison of both stimulus categories suggests that religious thinking is more associated with brain regions that govern emotion, self-representation, and cognitive conflict, while thinking about ordinary facts is more reliant upon memory retrieval networks.


While religious and nonreligious thinking differentially engage broad regions of the frontal, parietal, and medial temporal lobes, the difference between belief and disbelief appears to be content-independent. Our study compares religious thinking with ordinary cognition and, as such, constitutes a step toward developing a neuropsychology of religion. However, these findings may also further our understanding of how the brain accepts statements of all kinds to be valid descriptions of the world.

Read the paper on the PLoS ONE website.

Download the PDF.

Citation: Harris S, Kaplan JT, Curiel A, Bookheimer SY, Iacoboni M, Cohen MS. (2009) The Neural Correlates of Religious and Nonreligious Belief. PLoS ONE 4(10): e7272.

The stimuli used in these experiments were first tested online, in a series of questionnaires completed by thousands of visitors to The goal of this opinion research was to produce two categories of stimuli – factual and religious – which would elicit reliable responses from participants in the experiment. The experimenters needed factual statements that atheists and Christians would accept equally and religious statements that would divide them more or less diametrically. Statements like the following worked well in the online survey:

While the purpose of this survey was to refine a set of experimental stimuli, the results were interesting in their own right. Some of the survey data can be viewed here.

Follow-up study (sponsored, in part, by Project Reason):

Douglas, P. K., Harris, S., Yuille, A., & Cohen, M. S. (2011, May 15) Performance comparison of machine learning algorithms and number of independent components used in fMRI decoding of belief vs. disbelief. Neuroimage. Volume 56, Issue 2, Pages 544-553.

Related Articles:

Bond, A. (2010) Belief in the Brain Scientific American Mind. (March).

Miller, L. (2009) Faith Impact. Newsweek. (October 1).

Healy, M. (2009) Religion: The heart believes what it will, but the brain behaves the same either way. The Los Angeles Times. (September 30).

Harris, S., Sheth, S.A., Cohen, M.S. (2008). Functional neuroimaging of belief, disbelief, and uncertainty. Annals of Neurology, 63(2), 141-147.

Sacks, O. & J. Hirsch. (2008). A Neurology of Belief Annals of Neurology, 63(2), 129-130.

Van Biema, D. (2008). My Nose, My Brain, My Faith. Time. (Jan. 10).

Van Biema, D. (2007). What Your Brain Looks Like on Faith. Time. (Dec. 14).

Shermer, M. (2008). Adam's Maxim and Spinoza's Conjecture. Scientific American. (March).