A word I like to throw around (especially when someone believes something different than what I believe) is epistemology. That’s the branch of philosophy that deals with the theory of knowledge, or how it is that we know what we know. When I think about epistemology I tend to think about the operation of my prefrontal cortex, as it carries out the so-called “executive function” of my brain: The evaluation of information gathered by the senses (these days, often via the distance-shrinking “perception engine” of the Internet), the use of logic, the rational weighing of evidence, and so on. There is also bias, including the predisposition to believe certain things because they match my a priori belief (see confirmation bias), but here I assume we’re still talking mostly about the prefrontal cortex.
But there is another aspect of knowledge that I too-frequently ignore. That’s the feeling of truth, the sense of certainty that accompanies knowing something. Here I suspect we’re moving beyond the prefrontal cortex into evolutionarily older structures. Where does that feeling come from?
An interesting disorder that may shed some light on this is prosopagnosia, or “face blindness”, in which a person has an inability to recognize faces, even if their ability to perceive the specific differences between one person’s face and another’s remains intact. Even more interesting (at least to me) is the somewhat-related disorder called the Capgras delusion, in which a person becomes convinced that someone they know well (like a close relative or loved one) has been replaced by an identical-looking stranger. In an NPR story from earlier this year (Seeing Impostors: When Loved Ones Suddenly Aren’t), Jad Abumrad and Robert Krulwich spoke with neuroscientist V.S. Ramachandran about a possible explanation for the Capgras delusion:
According to Ramachandran, when we see someone we know, a part of our brain called the fusiform gyrus identifies the face: “That looks like mom!” That message is then sent to the amygdala, the part of our brains that activates the emotions we associate with that person. In patients experiencing Capgras, Ramachandran says, the connection between visual recognition and emotional recognition is severed. Thus the patient is left with a convincing face — “That looks like mom!” — but none of the accompanying feelings about his mother.
Ramachandran holds that we are so dependent on our emotional reactions to the world around us, that the emotional feeling “that’s not my mother” wins out over the visual perception that it is. The compromise worked out by the brain is that your mother was somehow replaced, and this impostor is part of a malevolent scheme.
I see this as tying in with Justin Barrett’s notion of a Hyperactive Agency Detection Device. The idea is that humans have evolved to experience a deep-rooted, powerful sense of “agency” when perceiving certain kinds of phenomena, and (this is important) to do so even in cases when there is no agent. As just one example, in evolutionary terms it may have been beneficial for us to believe that that rustle in the bushes was a large, hungry predator stalking us, rather than the wind, and to believe that viscerally, on an emotional level, rather than treating it as a passing supposition that we might or might not be bothered to act upon. The energy our ancestors wasted by overreacting to windblown leaves was more than made up for, the theory goes, by the survival benefit conferred by being hyperalert to actual threats.
Having evolved this generalized mechanism for “knowing” things that are not necessarily so, we now experience all kinds of interesting consequences: A propensity to believe that the universe was created specifically for us by an imaginary, omnipotent being or beings. A belief that intelligent aliens from other worlds are kidnapping people, taking them aboard invisible spaceships, and subjecting them to anal probes. A belief that some dramatic, emotionally traumatic event (the assassination of John F. Kennedy, the 9/11 attacks) must have been the result of a conspiracy in which our own government was complicit. For a significant subset of the population, these and other conspiracy theories are not merely things that they suspect. They are things that they know.
Jonah Lehrer blogged yesterday about a recent study examining the role of a brain structure called the insula in mediating between physical sensations (like the feeling of warmth or cold one receives from holding a hot or cold object) and a willingness to extend trust to a trading partner: Trust and temperature. I especially liked this part:
We like to see ourselves as Promethean creatures, mostly liberated from this sack of meat we have to carry around for support. (John Updike, as usual, said it best: “We think we are what we think when in truth we are upright bags of tripe.”) But what the insula and these studies of embodied cognition demonstrate is that our mind is impossibly intertwined with carnal changes we can’t explain or comprehend.
I know what I know because my rational mind has analyzed facts and evidence, sure. But that’s not the whole story. The sensations delivered to me by my body — by chemical cues, sensations of warmth and cold, and the murky actions of older, deeper mechanisms that reach me as visceral emotions — play a large part. Perhaps the major part.
I just know it.