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1.5 THE BRAIN AND PERSONALITY 23

SECTION SUMMARY • The ancient theorists, especially Hippocrates and Galen, related differences in temperament/per sonality to differences in bodily fluids (humours) which excited the idea that physiology underpins personality. • Inspired by the early theorizing by the Ancient Greeks, Kant and Wundt proposed important ideas about personality, and the German psychi atrist, Ernst Kretschmer, went on to propose an influential morphological theory based on the observation of psychiatric patients and their body shapes. • In the US, William Herbert Sheldon advanced the morphological approach to personality in his con stitutional theory based on observed relationships We now have an established neuroscience of personal ity and even a journal devoted to this topic ( Personality Neuroscience , founded by one of the editors of this book, Philip Corr; also see Chapter 13). It is an inter esting scientific story as to how we have reached this point.We can start with one approach—which we now know is invalid—in detail, but it certainly helped to inspire the idea that we can learn a lot about the mind (and personality) from measuring the brain. Most people are familiar with phrenology. This was the attempt to infer psychological abilities by mea suring bumps on the skull. This approach, much rid iculed today, was developed in 1835 by the German physician Franz Gall, who claimed that the distances between bumps on the skull provide information about a person’s personality traits, character, and mental abilities (see Finger & Eling, 2019). According to Gall, we can measure the distance between these bumps on the skull to infer the size of the underlying 1.5.1 PHRENOLOGY

between physical characteristics, personality traits, and their social expression (e.g. criminality). • Systems of measurement were devised to relate bodily morphology/constitution to personality. • Other theorists who were inspired by the mor phological approach (e.g. Hans Eysenck) related personality to understanding criminal behaviour, reflecting the much earlier interest in this field by Cesare Lombroso who pioneered the scientific ap proach to the psychology of criminality. • Methodological and inferential problems plagued the association of morphology/constitution to per sonality due to its, essentially, correlational nature, and the issue of causal direction, and we still do not have an adequate personality account of the pro pensity to criminality and the commission of crime. brain areas. These measurements were said, for ex ample, to reveal information about a person’s per sonality traits—whether they are ‘friendly’, ‘prideful’, ‘murderous’, ‘kind’, ‘good with languages’, and so on. Gall even went so far as to propose a diagram detail ing the correspondence between brain areas and per sonality traits—this can be seen in Figure 1.5b, which shows an 1825 lithograph of Gall examining the skull of a young woman. Of course, the level of detail of these speculations was entirely out of proportion to what could properly be known at the time and, as result, phrenology was deemed a pseudoscience. However, the idea that brain areas and personality features may be related was born. Today, it is common to measure the size of brain areas and relate them to psychological function (e.g. structural magnetic resonance imaging). Phrenology does not seem too different—at least, in principle, if not in practice—to the neuroscience of personality we have today (DeYoung & Blain, 2020). If nothing else, phrenology serves as a reminder to us of how even ridiculous theories may have a kernel of truth that in spires future generations of researchers.

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1.5 THE BRAIN AND PERSONALITY

© Oxford University Press

© Oxford University Press