An article that I've meant to get around to reading for awhile is an interesting study by the somewhat controversial author Sam Harris. Harris is considered controversial by some because he's one of the so-called "4 horsemen" of the new atheism movement. I'll get into the differences between the new and old atheists later but for now its enough to say the difference is primarily in tone and tactial approach. New atheists tend to be more confrontational while old atheists are more inclusive of certain religious perspectives. What makes Harris an interesting figure is that during his rise to fame in the public realm, he also continued his work towards a doctorate in neuroscience. This gives him a unique perspective on academia and the nature of science.
This brings me to the article of the week. After that background, you might rightfully guess that Harris is interested in topics such as religion and belief. In 2007, Harris et al conducted a functional magnetic resonance imaging (fMRI) study testing subjects physiological responses to statements of belief, disbelief, and uncertainty. fMRI is quickly becoming the go to brain scanning method for neuroscience research. In a nutshell, when your brain activates certain areas, neurons in those areas fire. This creates a deficiency of nutrients (i.e. glucose and oxygen) for those neurons. What fMRI measures is what's called a BOLD (Blood-oxygen-level-dependence) signal. The BOLD signal is a measure of the blood volume in the brain. An increase in BOLD indicates an active area. This allows fMRI to have great spatial resolution (knowing the exact locations that are active) but somewhat slow temporal resolution (time it takes to measure signal) due to having to wait for the blood to move to the area.
On to the study! Harris and colleagues start off by claiming that there is a paucity of research in "belief itself at the level of the brain". I find this surprising as it seems like this is an area that would generate a lot of interest across disciplines. Although psychologists would be especially interested in this type of research, I can see applications in anthropology, sociology, and even medicine.
Harris et al mention the prefrontal cortex (PFC) as an an area involved in executive control of other brain functions. The PFC helps regulate brain and bodily functions through what's known as "top-down" processing. Top-down processing is when you take a concept and break it down (or let it influence) smaller components perceptually. Bottom-up is the exact opposite, smaller components are pieced together to form a larger concept. This concept doesn't only apply to perception, top-down vs. bottom up can be described in more general terms of information processing.This is important because a reasonable hypothesis would be to expect the PFC to be involved in the modulation of "belief pathways" depending on ones past experiences and preconceived notions.
The authors presented 14 adults with different categories of belief statements through a video-goggle display. The statements were divided into 7 categories (mathematical, geographical, semantic, factual, autobiographical, ethical, and religious). Within each category, statements were designed to be unambiguously true, false, or undecidable. The authors later refer to these three categories as belief, disbelief, and undecidable trials in their analysis. An example of a a category (factual) is as follows:
Most people have 10 fingers and 10 toes.
Eagles are common pets.
The Dow Jones Industrial Average rose 1.2% last Tuesday.
True, false, and undecidable statements were blocked together in order to take proper scans (remember the fMRI takes awhile). Reaction times were taken from when a trial began (stimulus presented) to when the subject gave a response (true, false, or undecidable).
The reaction times for belief trials were significantly faster than those for disbelief and uncertainty trial. This supports what the authors refer to as "Spinoza's conjecture". Spinoza's conjecture claims that the mere comprehension of a statement entails the tacit accpetance of it being true wheras disbelief requires a subsequent process of rejection. It requires more "psychological effort" to reject (disbelieve) a statement than accept (believe) it. One can imagine how this relates to skepticism. It's often said that the ideas that we are most comfortable in accepting are the ideas that we need to be most skeptical of. It's much easier to go along with what we already believe than to make the extra effort to fairly examine an opposing viewpoint. It's easier to keep our minds closed and we need to to work to keep our minds open.
The area most associated with assent (belief) was the ventromedial prefrontal cortex (VMPFC). This is not surprising given the VMPFC's involvement in linking factual knowledge with relevant associations as well as goal-based action selection. Abnormalities in this area tend to make people awful at gambling since they can't make render individuals incapable of deciding between right and wrong actions. They just don't seem to be able to recognize the difference. This region also had connections with the limbic region indicating a emotional link to beliefs.
The disbelief trials showed some of the strongest responses in the anterior insula. This is an area involved in the sensation of taste. When you disagree with something, the idea literally "tastes" bad to you. It activates this "disgust" pathway that affects your future decisions.
The anterior cingulate cortex was found to be activated during uncertainty trials. According to the authors, this region is involved in "error detection, response conflict, and regularly responds to increases in cognitive load and interference". This is expected since one experiences a bit of confusion when first presented with a uncertainty trials. Your brain needs to increase the cognitive load to make sense of the statement.
The authors also note the basal ganglias involvement in "mediating the cognitive and behavioral differences between decision and indecision". Both belief and disbelief trials showed activation over uncertainty trials. The basal ganglia has been shown to be involved in cognitive planning and motor actions (taken after a belief is made).
One limitation the authors acknowledge is that the study is preliminary. Since the authors didn't find any work beforehand, they were not able to generate a original hypothesis. All decisions had to be made without a priori prediction. This can potentially lead to problems with data interpretation during analysis. The authors correct for this by being conservative in their analysis. They report on only the "strongest" evidence for activation of certain areas.
The authors suggest further research into types of beliefs. This study raises more interesting questions than it probably answers. Are their different categories of beliefs? What are the differences between these categories? As Oliver Sacks asks in an editorial on this study, "is a belief a simple statement whose truth can be checked"? In closing the authors suggest their research would be relevant to studies of deception. In the future, it may be possible to control for the placebo effect through brain imaging in randomized controlled trials to tell if somebody is actually believing in the product.
I would suggest reading this study if you have time (it's short). I plan to follow up on the work of Harris and colleagues in future posts.
Look, a bunny!
-Bruce Smith
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