The Believing Brain - Michael Shermer [64]
The connection between dopamine and belief was established by experiments conducted by Peter Brugger and his colleague Christine Mohr at the University of Bristol in England. Exploring the neurochemistry of superstition, magical thinking, and belief in the paranormal, Brugger and Mohr found that people with high levels of dopamine are more likely to find significance in coincidences and pick out meaning and patterns where there are none. In one study, for example, they compared twenty self-professed believers in ghosts, gods, spirits, and conspiracies to twenty self-professed skeptics of such claims. They showed all subjects a series of slides consisting of people’s faces, some of which were normal while others had their parts scrambled, such as swapping out eyes or ears or noses from different faces. In another experiment, real and scrambled words were flashed. In general, the scientists found that the believers were much more likely than the skeptics to mistakenly assess a scrambled face as real, and to read a scrambled word as normal.
In the second part of the experiment, Brugger and Mohr gave all forty subjects L-dopa, the drug used for Parkinson’s disease patients that increases the levels of dopamine in the brain. They then repeated the slide show with the scrambled or real faces and words. The boost of dopamine caused both believers and skeptics to identify scrambled faces and real and jumbled words as normal. This suggests that patternicity may be associated with high levels of dopamine in the brain. Intriguingly, the effect of L-dopa was stronger on skeptics than believers. That is, increased levels of dopamine appear to be more effective in making skeptics less skeptical than in making believers more believing.8 Why? Two possibilities come to mind: (1) perhaps the dopamine levels of believers are already higher than those of skeptics and so the latter will feel the effects of the drug more; or (2) perhaps the patternicity proclivity of believers is already so high that the effects of the dopamine are lower than those of skeptics. Additional research shows that people who profess belief in the paranormal—compared to skeptics—show a greater tendency to perceive “patterns in noise,”9 and are more inclined to attribute meaning to random connections they believe exist.10
Finding the Signal in the Noise
What is it that dopamine does, exactly, when it enhances belief? One theory—promulgated by Mohr, Brugger, and their colleagues—is that dopamine increases the signal-to-noise ratio (SNR), that is, the amount of signal your brain will detect in background noise.11 This is the error-detection problem associated with patternicity. The signal-to-noise ratio is, in essence, a problem in patternicity—finding meaningful patterns in both meaningful and meaningless noise. The SNR is the proportion of patterns that your brain detects in the background noise, whether or not the patterns are real. How does dopamine affect this process?
Dopamine enhances the ability of neurons to transmit signals between one another. How? By acting as an agonist (as opposed to antagonist), or a substance that enhances neural activity. Dopamine binds to specific receptor molecule sites on the synaptic clefts of the neurons, as if it were the CTS that normally bind there.12 It increases the rate of neural firing in association with pattern recognition, which means that synaptic connections between neurons are likely to increase in response to a perceived pattern, thereby