Your credulous brain
The neuroscientific investigation of belief began in 2008, when Sam Harris at the University of California, Los Angeles, put people into a brain scanner and asked them whether they believed in various written statements. Some were simple factual propositions, such as “California is larger than Rhode Island”; others were matters of personal belief, such as “There is probably no God”. Harris found that statements people believed to be true produced little characteristic brain activity – just a few brief flickers in regions associated with reasoning and emotional reward. In contrast, disbelief produced longer and stronger activation in regions associated with deliberation and decision-making, as if the brain had to work harder to reach a state of disbelief. Statements the volunteers did not believe also activated regions associated with emotion but in this case pain and disgust.
Harris’s results were widely interpreted as further confirmation that the default state of the human brain is to accept. Belief comes easily; doubt takes effort. While this doesn’t seem like a smart strategy for navigating the world, it makes sense in the light of evolution. If the sophisticated cognitive systems that underpin belief evolved from more primitive perceptual ones, they would retain many of the basic features of these simpler systems. One of these is the uncritical acceptance of incoming information. This is a good rule when it comes to sensory perception as our senses usually provide reliable information. But it has saddled us with a non-optimal system for assessing more abstract stimuli such as ideas.