Imagine coming home to your spouse and finding someone who looks and acts exactly like your spouse, but you have the strong feeling that they are an imposter. They don’t “feel” like your spouse. Something is clearly wrong. In this situation most people conclude that their spouse is, in fact, an imposter. In some cases this has even led to the murder of the “imposter” spouse.
This is a neurological syndrome known as Capgras delusion – a sense of hypofamiliarity, that someone well known to you is unfamiliar. There is also the opposite of this – hyperfamiliarity, the sense that a stranger is familiar to you, known as Fregoli delusion. Sufferers often feel that they are being stalked by someone known to them but in disguise.
Psychologists and neuroscientists are trying to establish the wiring or “neuroanatomical correlates” that underlie such phenomena. What are the circuits in our brains that result in these thought processes? A recent article by psychologist Philip Garrans explores these issues in detail, but with appropriate caution. We are dealing with complex concepts and some fuzzy definitions. But in there are some clear mental phenomena that reveal, at least to an extent, how our minds work.
The “reality testing” model discussed by Garran reflects the overall hierarchical organization of the brain. There are circuits that subconsciously create beliefs, impressions, or hypotheses. We also have “reality testing” circuits, specifically the right dorsolateral prefrontal circuitry, that examine these beliefs to see if they are internally consistent and also consistent with our existing model of reality. Delusions, such as Capgras and Fregoli, result from a “metacognitive failure” of these reality testing circuits.
Garran and others argue that dreams are a normal state we all experience in which our reality-testing circuitry is either off or hypofunctioning. This is why our dreaming selves accept dream events that are clearly internally inconsistent or at odds with our model of reality. When we wake up, if we remember our dream, we are often struck by how “bizarre” our dream was and marvel at how our dreaming self accepted the clearly unreal dream.
The question Garran explores is whether or not pathological delusional states are neuroloanatomically similar to the dreaming state. Both, he argues, may result from a failure of reality testing. Part of the problem of exploring this hypothesis is that “reality testing” is a broadly defined concept. What, exactly, is the process? It seems to be a higher level inference about what is likely to be real based upon logic, internal consistency, and existing knowledge.
Here is my own synthesis of what we currently know about how our brains work with respect to belief and reality testing:
There are multiple identified processes, acting mostly subconsciously, that “present” tentative beliefs or conclusions to our conscious awareness. These processes include our sensory perceptions, which are highly constructed and are not objectively reliable. Our brains not only construct our perceptions but give them meaning. We don’t just see shapes, we see objects that have a reality and a purpose. We also see people, who have emotional content, including familiarity. Locations also are imbued with a sense of familiarity or unfamiliarity.
Our memories are also highly constructed and malleable. We update our memories with new information every time we recall them. They become part of our dynamic internal model of reality.
There are also a host of biases and needs pushing our model of reality and our construction of events in a direction that is emotionally comforting and satisfying to us.
Further, we have a set of heuristics or inherent logic by which we, by default, attempt to make sense of the world. This includes an inherent (flawed) sense of probability. There are also inherent tendencies, such as the tendency to see patterns, to detect agency in others and in our environment, and to weave compelling narratives.