Study of the shape of the skull as an indication of mental abilities and character traits.
Franz Joseph Gall stated the principle that each of the innate mental faculties is based in a specific brain region ("organ"), whose size reflects the faculty's prominence in a person and is reflected by the skull's surface. He examined the skulls of persons with particular traits (including "criminal" traits) for a feature he could identify with it. His followers Johann Kaspar Spurzheim (1776–1832) and George Combe (1788–1858) divided the scalp into areas they labeled with traits such as combativeness, cautiousness, and form perception. Though popular well into the 20th century, phrenology has been wholly discredited.