The next time you say, “so and so should have her head examined,” remember that this was literally done in the 19th century.
Phrenology, as it became known, is the study of brain function. Specifically, phrenologists believed that different parts of the brain were responsible for different emotional and intellectual functions. Furthermore, they felt that these functions could be ascertained by measuring the bumps and indentations in your skull. That is, the shape of your skull revealed your character and talents.
Viennese doctor and anatomist Franz Josef Gall originated phrenology, though he called it cranioscopy. He was correct in saying that brain function was localized (this was a novel idea at the time), but unfortunately, he got everything else wrong.
When Gall was young, he noticed a relationship between people’s attributes and behaviors and the shape of their heads. For instance, he observed that his classmates who had better memories had protruding eyes. This inspired him to start forming his theories and collecting anecdotal evidence. It’s this type of evidence that is the foundation of phrenology.
The problem? Phrenologists would simply dismiss cases that didn’t support their principles, or just revise their explanation to fit any example.