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Diagnosing behaviour

Phrenological head of Francis Gall, London, England, 1823

Phrenological head of Francis Gall, London, England, 1823

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Psychological or behavioural disorders can be difficult to diagnose. Their symptoms are sometimes less visible, or more ambiguous, than symptoms of physical disease. Laboratory tests that conclusively identify schizophrenia or depression exist only in science fiction. The stigma often associated with mental illness creates new challenges for the person diagnosed with it. The new classification system was partly inspired by psychiatrist Emil Kraepelin's criticisms of psychoanalysis.

Looking for outward signs of mental ‘deficiency’


Swiss pastor Johann Caspar Lavater published his theories of physiognomy in the 18th century. These included images of ‘idiots’ - people born with mental disabilities. Lavater claimed ‘an exact relationship exists between the soul and the body’. He argued this was the basis of an exact science, which he called physiognomy.

French asylum physician Philippe Pinel took this idea further in his 1801 Treatise on Insanity. He compared the skulls of persons of normal and low intelligence. He also compared the different features of two patients: a ‘maniac’, who experienced symptoms of mental illness only temporarily, and an ‘idiot’, a man with permanent mental illness. The popular 19th-century practice of phrenology claimed a person’s mental features and problems were detectable by ’reading’ the shape of the skull.


Throughout the 19th century, doctors such as Charles Bell tried to establish classifications of ‘mental and moral disorders’. These would help physicians diagnose various mental or emotional disorders on the basis of descriptions and images. The invention of photography in the mid 19th century saw medical scientists document and investigate the facial features, gestures and behaviours of criminals and patients in asylums.

Italian criminologist Cesare Lombroso and British scientist Francis Galton used photographs to establish criminal and psychological ‘types’. French neurologist Jean-Martin Charcot, one of Pinel’s successors, classified varieties and stages of hysteria by photographing his hypnotised patients’ striking gestures and movements.


Changing definitions of psychological illness

Another problem in psychological diagnosis is establishing what counts as a disease. A 1972 study showed psychiatrists in New York diagnosed schizophrenia twice as often as psychiatrists in London. Both cities’ patients acted in ways that might have been symptoms of either schizophrenia or mood disorder, which have very different treatments and outcomes. American psychiatrists subsequently narrowed their definition of schizophrenia. They also reorganised the classification of mental illnesses to match more reliably a specific disorder to a specific treatment. This had tremendous consequences worldwide for the practice of psychiatry, thanks to a new revision of the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM). Some old diagnoses, such as hysteria, were excluded from newer versions of the DSM as unworkable. Other previously included diagnoses, such as homosexuality, were removed only after considerable political activism challenged the idea that sexuality was a medical issue.

Consequences of diagnosis

Psychological symptoms often have a stigma attached. Many people diagnosed with depression, for example, still feel the need to hide that fact. The diagnosis of mental health issues has had far-reaching positive and negative consequences. Some Victorian women feared their husbands would have them diagnosed with insanity to allow their removal to an asylum. Diagnosis for soldiers during the First World War could make the difference between receiving medical treatment for shell shock or a court martial for cowardice or desertion of duty.

In court, the accused person’s mental state is crucial for the question of responsibility. Being defined as legally ‘insane’ can affect the outcome of a trial when a defendant is declared not guilty by reason of insanity. Finally, in the United States and many other countries, health insurers and policy-makers use the diagnostic categories in the DSM to determine what sorts of treatment for mental illness are eligible for reimbursement.


S L Gilman, Seeing the Insane - A Cultural History of Madness and Art in the Western World (Lincoln, NE/London: University of Nebraska Press, 1996)

Y Kawakita, S Sakai and Y Otsuka (eds), History of Psychiatric Diagnoses, Proceedings of the 16th International Symposium on the Comparative History of Medicine - East and West, September 1991 (Tokyo: Ishiyaku, 1997)

I Hacking, Mad Travellers - Reflections on the Reality of Transient Mental Illness (London: Free Association Books, 1998)

S A Kirk and H Kutchins, The Selling of DSM: The Rhetoric of Science in Psychiatry (New York: De Gruyter, 1992)

R Cooter (ed.), Phrenology in Europe and America (London: Routledge/Thoemmes Press, 2001)

F J Gall and J C Spurzheim, Anatomie et physiologie du systeme nerveux en general (1810)

J van Wyhe, Phrenology and the Origins of Victorian Scientific Naturalism (Aldershot: Ashgate, 2004)




A mental disorder that has symptoms of delusions, hallucinations and a loss of a sense of self and relationship to the external world that lasts over a long period of time (more than six months).


A mental state associated with acute sadness. Activity can be decreased, especially interaction with others, and sleep, appetite, and concentration can also be disturbed.


The study of the functions, anatomy and organic disorders of the nervous system.