MARK TWAIN WAS a noted 19th century American writer and humorist. He often elaborated upon the personalities of his characters, and his observational skills reflected a strong interest in psychology. Similarly, he found an interest in phrenology, a pseudoscience that purported to characterize personality traits according to elevations or depressions on the head. Twain's style is clearly reflected in the interesting essay he wrote regarding his personal experience with phrenology.