born November 19, 1898, Warwick, Rhode Island, U.S.—died September 16, 1977, Cambridge, Massachusetts, American psychologist and physician who was best known for his theory associating physique, personality, and delinquency.

Influenced by the pragmatism of American philosopher and psychologist William James and by his background as a naturalist who had also studied animals, Sheldon became convinced that the psychological makeup of humans had biological foundations. He constructed a classification system that associated physiology and psychology, which he outlined in The Varieties of Human Physique (1940) and The Varieties of Temperament (1942).

In the 1940’s, William Herbert Sheldon associated body types with human temperament types. He claimed that a body type could be linked with the personality of that person. He says that a fat person with a large bone structure tends to have an outgoing and more relaxed personality while a more muscular body-typed person is more active and aggressive. A slim or scrawny person with thin muscles is usually characterized as quiet or fragile. He split up these body/personality types into three categories called somatotypes.

  • Endomorphic- An Endomorphic somatotype is also known as a viscerotonic. The characteristic traits of this somatotype usually includes being relaxed, tolerant, comfortable, and sociable. Psychologically, they are also fun-loving, good humored, even-tempered, and they love food and affection. The Endomorph is physically “round”. They have wide hips and narrow shoulders that give a pear-shape. They tend to have a lot of extra fat on their body and on their arms and thighs. They have skinny ankles and wrists that make the rest of their body look even bigger.
  • Ectomorphic– An ectomorph is the complete opposite of the Endomorph. Physically, they have narrow shoulders, thin legs and arms, little fat on the body, a narrow face and a narrow chest. They may eat just as much as the endomorph but never seem to gain any weight. They always stay skinny. Personality wise, they tend to be self- conscious, socially anxious, artistic, thoughtful, quiet, and private. They always keep to themselves and are a afraid to branch out.
  • Mesomorphic– The mesomorph is in between the endomorph and thin ectomorph. They have an attractive and desirable body. Physically, they tend to have a large head and broad shoulders with a narrow waist. They have a strong muscular body and strong arms and legs and little fat on the body. They work for the body they have so that they could have an attractive body. Psychologically, the mesomorph is adventurous and courageous. They are not afraid to break out and do new things with new people. They are assertive and competitive and have a desire to have power and be dominant. They love taking risks and chances in life.


The original work of Sheldon was used to characterize criminals and he found that most of the criminals were mesomorphs because violent crimes were usually committed by big strong men. It makes sense because according to Sheldon’s theory, people with a muscular and attractive body tend to be competative and want power and dominance. This also proved that mesomorphic people are usually criminal in nature.


  • Although his research was groundbreaking, it was criticized on the grounds that his samples were not representative and that he mistook correlation for causation.
  • Sheldon did not use factor analysis, which was still developing when he wrote, but a less refined method called cluster analysis. Later investigators attempted to put his data in more mathematically sophisticated factorial forms.
  • Sheldon did have large numbers of photographs spread out before him when he selected the types, but that hardly makes the procedure empirical.


born Oct. 8, 1888, Wüstenrot, Ger.—died Feb. 8, 1964, Tübingen, W.Ger., German psychiatrist who attempted to correlate body build and physical constitution with personality characteristics and mental illness.

Kretschmer studied both philosophy and medicine at the University of Tübingen, remaining there as an assistant in the neurologic clinic after completing his studies in 1913. The next year, he published his dissertation on manic-depressive delusions, anticipating his later work in mental illness. He studied hysteria while a military physician during World War I, developing a treatment in which victims of battle hysteria were quieted in dark chambers and treated with electrical impulses. After the war, he returned to Tübingen as a lecturer and began writing books containing his psychological theories. His best-known work, Körperbau und Charakter (1921; Physique and Character), advanced the theory that certain mental disorders were more common among people of specific physical types. 

Kretschmer’s Classification:

German psychologist Kretschmer has attempted to correlate physique and character. From his studies on mental patients, he found that certain body types are associated with particular types of mental disorders. He has classified personalities into four types:

  • Pyknic type: These are people who are short and having round body. They will have personality traits of extraverts. These people are more prone to suffer from a mental disorder called Manic Depressive Psychosis (MDP).
  • Asthenic type: These people will have a slender or slim body. They will have the personality traits of introverts. These people are more prone to suffer from a serious mental disorder called Schizophrenia.
  • Athletic type: These people will have strong body. They are more energetic and aggressive. They will be strong enough, determined, adventurous and balanced. They are comparable with ambiverts. They are more prone to suffer from MDP.
  • Dysplastic type: These people will have unproportionate body and do not belong to any of the three types mentioned above. This disproportion is due to hormonal imbalancement. Their behaviour and personality are also imbalanced.


  • The first is a failure to control the age factor. Since manic-depressive psychosis occurs later in life than schizophrenia, and since there is a tendency for individuals of the various types to become more pyknic as they grow older, the coincidence of manic-depressive psychosis and pyknic constitution appears to be largely a result of the age factor.
  • The second is the greater tendency toward physical deterioration in schizophrenia, which would have the effect of producing and maintaining leptosome types among schizophrenics. These factors greatly weaken if they do not entirely invalidate Kretschmer’s theory.
  • His work was criticized because his thinner, schizophrenic patients were younger than his pyknic, manic-depressive subjects, so the differences in body type could be explained by differences in age. Nevertheless, Kretschmer’s ideas to some extent entered into popular culture and generated further psychological research.


The concept of personality has been studied for at least 2,000 years, beginning with Hippocrates in 370 BCE (Fazeli, 2012). Hippocrates theorized that personality traits and human behaviors are based on four separate temperaments associated with four fluids (“humors”) of the body: choleric temperament (yellow bile from the liver), melancholic temperament (black bile from the kidneys), sanguine temperament (red blood from the heart), and phlegmatic temperament (white phlegm from the lungs) (Clark & Watson, 2008; Eysenck & Eysenck, 1985; Lecci & Magnavita, 2013; Noga, 2007). Centuries later, the influential Greek physician and philosopher Galen built on Hippocrates’s theory, suggesting that both diseases and personality differences could be explained by imbalances in the humors and that each person exhibits one of the four temperaments.

The four temperaments and their predominant humors are as follows:

  • Sanguine: blood
  • Phlegmatic: phlegm
  • Choleric: yellow bile
  • Melancholic: black bile

Arabic terms are as follows:

Sanguine: Damawiyy

Phlegmatic: Balghamiyy

Choleric: Safrawiyy

Melancholic: Sauda

The predominance of one humor is said to affect one’s appearance and behavior.

When we are stressed, overtired, under sustained pressure, or depressed, we can lose sight of our natural temperament, both the gifts and the challenges.

  • A melancholic can become rigid, pessimistic, inflexible and self-centred.
  • A choleric can become bossy, uncaring, sharp, aggressive.
  • A sanguine an become emotional flighty, (air headed) and unable to finish things.
  • A phlegmatic might be lazy and just not want to get out of bed at all.

In friendship we seek people of similar temperament to enjoy, feel affirmed, and good about ourselves. In relationship, we gain from the opposite temperament to compliment us and provide children with a wider landscape of support and modeling.

The Hippocratic theory today :

Both Hippocrates and Galen, as well as all of their followers, designed and complemented the theory of the four humors based on observations. However, they didn’t use the scientific method. That’s why it has fallen into disuse. Today, people don’t consider it to be scientifically viable.

Nevertheless, the theory of the four humors was the first serious attempt to classify different personality types. It’s also very interesting that these thinkers were able to link emotions to physiological issues.

Actually, Hippocrates’ and Galen’s theories inspired the first psychologists. These thinkers were very intuitive. Their classifications approximated the different personality types that researchers would identify almost 2,000 years later. This means that these ancient Greeks were the precursors of modern health sciences.

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