Interesting nugget from Keith Humphreys’ post on Christopher Hitchens’ illness:
For about eight years, I was a hospice volunteer, and had the honor to attend many people throughout their dying process. One of the most reliable rules was that people died as they had lived. Happy people were happy at the end, crabby people were crabby, anxious people were anxious. The story of human personality development is largely one of continuity. Temperamental differences measured within an hour of birth predict temperament 20 years later, and people who win million dollar lotto prizes tend, within a year, to return to being precisely as happy or unhappy as they were before their big win.
Humphreys’ point is that people facing death rarely undergo a dramatic religious conversion. But I’m just as curious about his line on infant temperaments. Can we tell what kind of adult is in the making by the way a newborn behaves?
It turns out there is research linking infant temperament to adult brain structure:
Conclusions To our knowledge, this is the first demonstration that temperamental differences measured at 4 months of age have implications for the architecture of human cerebral cortex lasting into adulthood. Understanding the developmental mechanisms that shape these differences may offer new ways to understand mood and anxiety disorders as well as the formation of adult personality.
However, developmental psychologist Jerome Kagan, author of The Temperamental Thread, notes that this does not mean we can predict adult personality per se:
Knowledge of a child’s temperaments does not predict their adult personality profiles very well. Temperaments act primarily by preventing a person from developing a certain personality, rather than determining a specific type. For example, we call one of our infant temperaments high-reactivity. These infants are easily aroused by any event that is new or unexpected. When we assessed a large group of high reactives at 15 years of age and asked what proportion were extremely shy, anxious, timid, or cautious we learned that about 25 percent had such a profile. One might conclude that their infant temperament was not very predictive. That conclusion is reasonable because their environments have shaped their temperaments in distinct ways. But now let us ask: what proportion of high reactives has been, over the past 12 or 13 years, consistently ebullient, risk-prone, and socially outgoing? The answer is 5 percent. We do very well when we predict what they will not be for we predict correctly for 95 percent of these adolescents.
Almost everyone can learn to play tennis. But how many can play like Roger Federer? Not many, because their biology prevents them from attaining this level of talent. If you knew my genome the day I was born, you might be able to predict with great confidence that I would not play as well as Roger Federer. But you would be wrong if you said that this boy will never learn to play tennis. Temperaments constrain, rather than predict, the future. Their primary role is to limit what might develop.
I’m a rank layperson with no special insights into this. I’m just fascinated by the topic of what it is that makes us who we are.