Myths of the Triune Brain and the Rational Human Mind

This post is motivated in part by Lisa Feldman Barrett’s revolutionary book “HOW EMOTIONS ARE MADE.”  Unfortunately, Carl Sagan popularized the notion of a triune brain in his book “The Dragons of Eden.”  The model begins with ancient subcortical circuits for basic human survival, which we allegedly inherited from reptiles.  Sitting atop those circuits is an alleged emotion system, known as the “limbic system”  that we supposedly inherited from the early mammals.  Wrapped around this so-called limbic system is our allegedly  rational and unique human cortex.  Any expert in brain evolution knows that humans don’t have an animal brain gift-wrapped in cognition.  Neuroscientist Barbara L. Finlay, editor of the journal “Behavior and Brain Sciences” says  that “mapping emotion onto just the middle part of the brain, and reason and logic onto the cortex is just plain silly.  All brain divisions are present in all vertebrates.”  Brains evolve as effective companies do, by reorganizing as they expand to keep themselves efficient and nimble.

Dr. Barrett’s bottom line is this:  “the human brain is anatomically structured so that no decision or action can be free of interoception and affect, no matter what fiction people tell themselves about how rational they are.   Your bodily feeling right now will project forward to influence what you will feel and do in the future.  It is an elegantly orchestrated, self-fulfilling prophecy, embodied with the architecture of the brain.”

One of the most cherished narratives in Western thought, is that the human mind is a battlefield where cognition and emotion struggle for the control of behavior.  Modern neuroscience does not back up this narrative, nor does human behavior.  Much research has clearly debunked this narrative.  There are many posts on this blog on behavioral economics (to find them enter “behavioral economics” into the healthy memory blog search.)  Behavioral economics was born by the research of Kahneman and Tversky.  Unfortunately, mainstream economics is dominated by the assumption of the rational mind.  This assumption makes the underlying mathematics tractable.  They are tractable but wrong.  Mainstream economics did not expect the financial crash of 2008, nor the market crash of 1929 for that matter.

Dr. Barrett writes, “You cannot overcome emotion through rational thinking, because the state of your body budget is the basis for every thought and perception you have, so interoception and affect are built into every moment.  Even when you experience yourself as rational, your body budget and its links to affect are there, lurking beneath the surface.”

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