I’m going to try something new here for a moment. I’m going to use a theory from evolutionary biologist and researcher on the science of love, Helen Fisher, to chemically define the four main levels of development in the human brain. The second term in the following list is Helen Fisher’s name for that particular personality type, and the third term is Plato’s and Keirsey’s “temperament” type. And the final item is the primary chemical governing that state/stage of human motivation (personality), according to Fisher’s fMRI research.
Physical – Explorer – Artisan (xSxP) – Dopamine
Emotional – Builder – Guardian (xSxJ) – Serotonin
Intellectual – Director – Rational (xNTx) – Testosterone
Spiritual – Negotiator – Idealist (xNFx) – Estrogen
Ideally (Hi I’m mostly a spiritual “Negotiator” type these days, can you tell? :-) everyone would have all of the positive abilities, and healthy levels of these brain chemicals, of all of these different stages by the time they reach middle age. But those who have major deficiencies and/or toxicities during one of the stages of development will probably not be as strong in that area. And will likely either try harder to get that chemical, by forcing themselves to be more like that type in some way (possibly by even taking drugs), or might rebel against that type, and be antagonistic towards anyone showing that sort of personality (including themselves). Though my guess is that it might not be possible for them to ever be strong in that area, and they might be better off focusing on their abilities and strengths in other areas, and accept their “disability” and just get on with life. :-)
This is just a very early test of this idea. So comments are especially welcome. Next comes some more research into the parts of the brain that Fisher identified for these types and their chemicals. But it’s promising, as a way to help match the patterns with the specific biological and chemical processes of the brain, for a more well-rounded understanding of healthy growth and development in humans.