In the early nineteenth century, Franz Gall developed the phrenology theory of personality, which assumed that a person’s personality could be determined by measuring the bumps on his skull. Areas that he believed were associated with particular personality traits are indicated in this phrenology chart. Although Gall’s idea that brain functions, such as language, tend to be localized is true (as we learned in Chapter 2), the size of the bumps on a person’s head has nothing to do with their personality.