Today psychologists scan images of the brain, looking for areas that map feelings and sensations, trying to draw linkages between thoughts with the physicality of the brain.
Turns out that, despite the pop science stories we read in the New York Times, scientists still know little about what images of the brain tell us about the person.
Instead, images produced by functional MRIs let us know when people respond to stimuli, but we don’t really know what that means. A piece of your brain lights up—so—what?
In the 1850s phrenologists reasoned that areas of the brain represented specific attributes, ranging from love of family to obstinacy. They figured the larger the area, the greater the attribute.
So if the area of the brain thought to represent love of family was large, then the individual was rich with love.
If the area was small, then the individual lacked familial love.
Phrenologists developed theories based on what they observed in individuals, on a case by case basis.
If the patient was an intellectual, then phrenologists looked for an enlarged part of the brain that would explain intellect.
Similarly, they reasoned that idiots would have small intellectual segments in their brains.
Problem is scientists who practiced phrenology looked for evidence to confirm their beliefs. But when they found evidence that didn’t align with their theories, they discounted those cases.
Phrenologists famously pointed out that Africans and Native Americans had small brains that lacked compassion and rationality.
So they looked for skulls that would match their theories.
Philosopher Thomas Kuhn would argue theories need to change when you can’t explain why anomalies that don’t fit.
And if you continue to discover anomalies, something is wrong with the theory.
Phrenology eventually lost favor among scientists but not before politicians drew on their theories to justify policies that treated Indians, Africans and Asians as sub-human.
American Indians were said to be ill-equipped for civilization and politicians used scientific evidence on brain structure to sequester Indians on reservations.
Science helped justify “killing the Indian to save the man.”