Cognitive Research into Belief
(Evidence doesn't "prove" evolution - evolutionary theory (as does any theory) describes the evidence and provides a conceptual model for it. Man, if I could just correct that one misconception I would die a happy person!)
So don't expect too much from Harris's work, though I think it is very important. What Harris did was to subject 14 right-handed native speakers of English, with no history of psychiatric or neurological disorders and who were not taking any medication at the time, to a series of short statements that they viewed from a video-goggle display worn over their eyes while their brains (specifically the pre-frontal cortex) were being scanned using functional magnetic resonance imaging (fMRI).
The statements consisted of mathematical, geographical, autobiographical, religious, ethical, semantic, and factual assertions. All statements were designed to be clearly true, false, or undecidable. For example:
Mathematical: (2 + 6) + 8 = 16 [true]
Geographical: Wisconsin is on the West Coast of the United States. [false]
Autobiographical: You had eggs for breakfast on December 8, 1999. [theoretically knowable, but unable to be decided]
Religious: A Personal God exists, just as the Bible describes. [true or false depending on belief]
Jesus spoke 2,467 words in the New Testament. [theoretically knowable, but unable to be decided]
And so on.
Read his Experimental Design section carefully. Some people took issue with Harris's decision to have his subjects review their responses and flag any that the subject felt were erroneous or was not sure about. Harris removed these responses from the analysis. I agree with Harris's method, and don't think it affects his experiement, but some bloggers do not agree and think that it skews the results. These people are probably more qualified to judge than I am - however, my response is that (as theirs surely would be) the way to really know is to conduct more tests, on wider selections of the population, utilizing various methods.
Harris states in his Discussion section:
Several psychological studies[9-11] appear to support Spinoza's conjecture that the mere comprehension of a statement entails the tacit acceptance of its being true, whereas disbelief requires a subsequent process of rejection. Understanding a proposition may be analogous to perceiving an object in physical space: We seem to accept appearances as reality until they prove otherwise. Our behavioral data support this hypothesis, in so far as subjects judged statements to be true more quickly than they judged them to be false or undecidable.
For example, a nonreligious person reading the statement, "A Personal God exists, just as the Bible describes" would first accept the statement as true, then reject it, and the religious person would, upon reading the statement, "There is probably no actual Creator God" would likewise accept the statement as true, then reject it. What is established here is that any statement is first accepted as true by the brain, then subsequently rejected if the subject does not believe it to be true.
Harris discusses the limits of fMRI briefly.
fMRI studies in general have several limitations. Perhaps first and most important are those of statistical power and sensitivity. We chose to analyze our data at extremely conservative thresholds to exclude the possibility of type I (false-positive) detection errors, reducing our susceptibility to the problem of multiple comparisons. This necessarily increases our type II error (false-negative rate). Thus, we may have failed to detect activity in additional brain regions involved in the formation of belief states. Furthermore, in whole-brain studies such as these, the analyses implicitly assume uniform detection sensitivity throughout the brain, though it is well known that several brain regions, including the orbitofrontal and rectal gyri, show reduced magnetic resonance signal in the low-bandwidth fast imaging scans used for fMRI because of the relatively inhomogeneous magnetic field created there. Thus, false-negative rate may be further increased in these brain areas.
Here are his conclusions:
Mean reaction time differed between belief and disbelief. Disbelief > belief mean reaction time.
Mean reaction time did not differ significantly between disbelief and uncertainty; however, disbelief > uncertainty.
Harris correlates belief, disbelief, and uncertainty to activity within specific areas of the brain. (Not being versed in brain anatomy I can't tell you what this exactly means, which areas overlap or don't, ect. You'll have to read that and judge.)
He sums up his data thus:
The results of our study suggest that belief, disbelief, and uncertainty are mediated primarily by regions in the medial PFC, the anterior insula, the superior parietal lobule, and the caudate. The acceptance and rejection of propositional truth-claims appear to be governed, in part, by the same regions that judge the pleasantness of tastes and odors.
These results suggest that the differences among belief, disbelief, and uncertainty may one day be distinguished reliably, in real time, by techniques of neuroimaging. This would have obvious implications for the detection of deception, for the control of the placebo effect during the process of drug design, and for the study of any higher-cognitive phenomenon in which the differences among belief, disbelief, and uncertainty might be a relevant variable.
"The acceptance and rejection of propositional truth-claims appear to be governed, in part, by the same regions that judge the pleasantness of tastes and odors." I wonder if certain tastes and certain odors correlate with belief in certain truth-claims? Perhaps not.
I can't help but wonder, though, when I look at Harris's work (and I'm engaging in some really shameful speculation here, based on my completely subjective and anecdotal experience) at the taste in music, poetry, and art that creationists have, being that this stuff truly repulses me. It's not only that I find the dogma of creationism laughable; it's also my experience that I find creationists' tastes to be (aside from their liking Mozart or Chopin) largely kitchy and crass. When I see the crap they produce, I know something is wrong - and even if I believed every word they said, I couldn't stomach the way that they say it! Is there a connection between pseudoscience beliefs and sentimentality?
It's brain-food for thought.
(In other words, I would also die a very happy girl if I could get it into Ken Ham's followers' heads that they can come to my blog and type until their fingers fall off the "peace you will feel" if I were to believe in God, as they have been in response to my "Ken Ham's Museum Opens to Closed Minds" post, but they can't can't can't ever make me like the shitty art that they produce! Gaaa! ) ;-)