Sheldon’s Constitutional Theory: Somatotyping

Key Takeaways

  • Somatotype is a discredited theory of personality that associates different body compositions with various personality traits and behavioral characteristics. A somatotype refers to the bodybuilder or physique of a person.
  • There have been theories surrounding body composition and personality since antiquity. However, William Herbert Sheldon originated Somatotype in the 1940s.
  • According to Sheldon, there are three somatotypes: slim ectomorphs, muscular mesomorphs, and smooth endomorphs. Endomorphs, in his view, are relaxed and sociable, mesomorphs active and assertive, and ectomorphs quiet and restrained. Three somatotypes are ideal types: most people have a mixture of multiple somatotypes.
  • Sheldon was heavily influenced by Ernst Kretschmer’s constitutional psychology. Ernst Kretschmer, using a similar classification of body types, attempted to find correlations between body type and psychiatric syndromes. Sheldon, in contrast, focused more on personality.
  • Somatotype studies from Sheldon to present suffer from substantial flaws such as confounding results, small sample sizes, and inconsistent findings. Nonetheless, somatotype spread through the 1950s and was used in earnest attempts to characterize personality as late as the 1980s.
  • Despite the discredited nature of somatotype, people unaware of the theory are still influenced in their assessments of personality by body type. This can compromise scientific data in cases where participants are rating the personalities of people with different body types.

A somatotype, also known as a constitutional type, refers to the body build or physique of a person, particularly as it relates to their temperament or behavioral characteristics.

Numerous theorizers since antiquity have proposed various categories of somatotypes.

The term somatotype is used in the system of classification of human physical types developed by the American psychologist William Herbert Sheldon.

Early Somatotypology

Attempts to correlate body composition with certain personality traits has a legacy dating to antiquity in many parts of the world. One early example of early somatic typology is Hippocrates theory of the four humors.

According to Hippocrates, choleric temperaments were associated with yellow bile from the liver, melancholic temperament with black bile from the kidneys, sanguine temperament with red blood from the heart, and phlegmatic temperament with white phlegm from the lungs (Clark and Watson, 2008).

There are also traditional Eastern ways of classifying people for the purpose of medical and psychological treatments. For example, the Indian physician R. D. Lele found a correlation of somatotypes with Prakriti, which is a system of classifying personality.

Lele links mesomorphs to Kapha, endomorphs to Pitta, and ectomorphs to Vata types (Patwardhan, Mutalik, and Tilu, 2015).

W. H. Sheldon’s Three Somatotypes

In the 1940s, American psychologist William Herbert Sheldon developed a theory that associated body types with human temperament types.

Sheldon proposed that the human physique could be classified according to how much they are composed of three elements.

He called these classifications somatotypes, after the three layers of embryos: the endoderm, which develops into the digestive tract; the mesoderm, which develops into the muscle, heart, and blood vessels; and the ectoderm, which forms the skin and nervous system (Patwardhan, Mutalik, and Tilu, 2015).

William Sheldon (1942) proposed a

strong correlation between personality and somatotype (i.e. physique).

From a study of several hundred male physiques he derived three made body types:

  1. The ectomorph, characterized by a thin, wiry frame.
  2. The endomorph, heavy and rounded.
  3. The mesomorph, with a solid, muscular frame.

Human body types. Three figures. Forms: ectomorph, mesomorph and endomorph.

Ectomorphic Type

The ectomorph body type is characterized by long, thin muscles and limbs and low fat storage.

In everyday terms, ectomorphs are slim. Ectomorphs are not predisposed to store fat or build muscle (Patwardhan, Mutalik, and Tilu, 2015).

Mesomorphic Type

The mesomorph body type is predisposed to build muscle, but not store fat. They tend to be strong and solid, neither overweight nor underweight.

Their bodies may be described as rectangular in shape with an upright posture.

Mesomorphs are typically thought of as having an even weight distribution, muscular arms, legs, chest and shoulders, and a large heart (Patwardhan, Mutalik, and Tilu, 2015).

Endomorphic Type

Endomorphs are characterized by increased fat storage, a wide waist, and large bone structure.

Endomorphs, in everyday language, are fat. They have a smooth, round body, small shoulders, and shorter limbs.

They tend to carry weight in the lower abdomen, hips, and thighs rather than evenly distributed throughout the body (Patwardhan, Mutalik, and Tilu, 2015).

These body types could be modulated by body composition. Certain diets, exercises, and training techniques can change body composition.

For example, during starvation, an endomorph may resemble an ectomorph, while an athletic mesomorph may look like an endomorph as the result of muscle.

Aging can also increase the amount of fat tissue and its distribution, seemingly altering body type. However, there are certain characteristics of the somatotype that cannot be changed.

For instance, bone structure — save for a few changes due to the reduction of distance between joints due to aging or physical deformities — is a fixed characteristic.

Sheldon noted that the vast majority of criminal were mesomorphs. One explanation for this is that a solid muscular person becomes involved in crime at an early age due to their intimidating appearance.

Cultural conditions can also play a role in changing temperaments in all body types (Patwardhan, Mutalik, and Tilu, 2015).

The anthropologists’ Heath and Carter (1967) modified Sheldon’s original somatotyping method in order to make it reproducible and validatable.

Personality Characteristics of the Somatotypes

Sheldon (1954), in Atlas of Men, ascribed distinct sets of personality traits to each somatotype. He set these traits in three different dimensions.

  1. Ectomorph are were quiet, restrained, noon-assertive, sensitive, introverted, artistic, and self-conscious.
  2. Endomorph (also known as viscerotonic) were seen as relaxed, sociable, tolerant, comfort-loving, peaceful, good humored, and in need of affection.
  3. Mesomorph are active, assertive, vigorous, adventurous, dominant, and competitive.

Constitutional Psychology

Constitutional psychology is a systematic attempt to account for such psychological variables as temperament and character in terms of bodily shape and functions.

Somatotypes both fall under the larger umbrella of constitutional psychology and were influenced by the development of the field.

Ernst Kretschmer was the first major figure in constitutional psychology. During the first world war, Kretschmer became an army psychiatrist in charge of a treatment unit for soldiers suffering from combat neurosis, or “shell shock.”

Kretschmer viewed the behavior of those suffering from combat neurosis as consisting of primitive reflexes and instinctive reactions. These reflexes and reactions were performed in the body and manifested due to a regression to a more primitive and immature level of behavior (Kretschmer, 1925).

After the first World War, Kretschmer would focus on how the human body constitution related to character and temperament. Kretschmer was also interested in the relationship between various psychiatric syndromes and constitution and character.

Kretschmer saw the human constitution as the totality of a person’s inherent, inborn characteristics.

The heredity genotype of a person interacted with the environment to produce a phenotype, which consisted of physique, character, and temperament. These three aspects of the phenotype were thus all related (The Constitutional Psychiatry of Ernst Kretschmer, 1990, 1990).

Kretschmer, like Sheldon, argued that there were three types of physique: pyknic, leptosomic, and athletic.

To Kretschmer, most people had a mixture of these body types. Kretschmer associated different psychiatric disorders with different physiques. For example, leptosomic body types were more likely to have schizoid personality disorder, and those with an athletic type were more likely to have epilepsy (Kretschmer and Enke, 1936).

The fourth and most unusual body type that Kretschmer described was the plastic type, where all of the body proportions were out of balance. According to Kretschmer, dysplastic types had high risk of endocrine disorders and severe schizophrenia (Kretschmer, 1925).

Kretschmer also examined various psychological differences between the body types, for example, sensitivity to color and form, “splitting,” concept formation, and psychomotor speed (The Constitutional Psychiatry of Ernst Kretschmer, 1990, 1990).

Kretschmer’s work greatly and directly influenced William Sheldon’s constitutional theory of physique and temperament (1940). There were similarities between the endomorphic somatotype and Kretschmer’s pyknic types. Sheldon’s mesomorphic type and Kretschmer’s athletic type also had affinities.

Finally, Kretschmer’s leptosome corresponded to Sheldon’s ectomorph type. Sheldon rated every person he examined on a scale of one to seven for each of these somatotypes. Sheldon, influenced by Kretschmer, also rated each individual according to the amount of dysplasia — disproportion of bodily parts — they showed.

In contrast to Kretschmer, however, Sheldon was mostly concerned with personality and body type. He considered psychopathological syndromes to be due to an imbalance of components of each body type. To investigate this psychiatric aspect of Somatotyping, Sheldon and his followers carried out somatotyping of patients at psychiatric hospitals.

Sheldon found that catatonic and hebephrenic schizophrenics — that is, people with a form of schizophrenia associated with immobility and shallow and inappropriate emotional responses, respectively — had a higher amount of dysplasia — poorly-proportioned limbs — and gynandromorph — both male and female physical traits.

Meanwhile, people with paranoid schizophrenia and those with aggressive psychopathy were high on mesomorphy. Finally, those with manic depression tended to be both highly endomorphic and mesomorphic.

Despite the high correlation reported by Kretschmer and Sheldon between physique, personality, and mental illness, subsequent empirical research into the relationship between physique and personality has proven disappointing.

Indeed, these correlations between physique and psychiatric and personality traits may have ultimately been the result of confounding data, as the people who rated the physiques of participants often also related their personality. Later, better controlled studies did not confirm the original claims.

Research Studies

Stereotyped Somatotypes

Although Sheldon’s correlation between physique and temperament has been discredited, people still judge the personality traits of different body types in a stereotypical manner. Wells and Siegel (1961) set out to determine how people perceive the personalities of different somatotypes.

Wells and Siegel argue that people develop social stereotypes around physique because reactions to body build are likely to be an important feature of the individual’s social environment in terms of the way the individual is treated by others as well as in terms of the personality and character traits others expect of him.

This can contaminate temperament ratings in cases where study participants are aware of body characteristics, or even produce correlations which otherwise would not be found at all (Anastasi, 1958; Wells and Siegel, 1961).

Wells and Siegel found 120 adults across a range of sex and economic class from New Jersey. Each participant was shown four silhouette drawings. One of the drawings pictured a man of “average” physique, while the remaining three pictured the three body types described by Sheeldon (1954).

Each of the participants then rated each of the silhouettes on a scale of 24 opposite traits, such as ambitious-lazy, dependent-self-reliant, intelligent-unintelligent, fat-thin, and short-tall.

The researchers found that endomorphs tended to be rated as fatter, older, shorter, more old-fashioned, lazier, weaker, less attractive, more talkative, more warm-hearted and sympathetic, more good-natured and agreeable, more dependent on others, and more trusting of others than the other body types (Wells and Siegel, 1961).

Meanwhile, mesomorphs were rated as stronger, more masculine, better looking, more adventurous, younger, taller, more mature, and more self-reliant than the others.

Finally, the participants saw the ectomorph as thinner, younger, less masculine, more stubborn and inclined to be difficult, more pessimistic, and quieter than the endomorph and mesomorph (Wells and Siegel, 1961).

Because these stereotypes were obtained from people who had no conception of Sheldon’s somatotype theory, they give credence to the idea that people associate different temperaments with different body builds, comprising an implicit personality theory (Wells and Siegel, 1961).

Somatotype and Trainee Pilots

The 1950s and on saw a number of studies into how somatotype affects the personality traits of different populations. These populations were as far-ranging as seven-year-old children (Davidson et al., 1957), university women (Slaughter, 1968), and even top Croatian female cadet handball players (Cavala et al., 2013).

One typical study involved characterizing the personality and somatotype of male trainee pilots (Adams, 1985).

In this study, Adams (1985) attempted to use the Heath-Carter (1967) somatotype method on 21 aviation majors between 18 and 38 years of age who had earned their private pilot’s licenses.

The researcher distributed the Sixteen Personality Factor Questionnaire (Cattell, Eber, and Tatsuoka, 1970) during a lecture, and eighteen of the participants were stereotyped using the Heath-Carter technique.

Like other studies into somatotyping, this study suffered from severe methodological flaws. The non-participation of half of an already small sample size likely biased results.

Additionally, the ages were heavily weighted — there were 16 participants aged 20 and just one over 24. The researchers found that the somatotypes of the trainee pilots were comparable to the average somatotype of college men (Sheldon, Stevens, and Tucker, 1940); however, the participants were significantly less ectomorph than those in the general college-aged population.

Adams (1985) also found correlations between individual personality traits and somatotype components. Two of the correlations Adams found to be of interest were the so-called “Factor L” — a measure of surgency, mistrusts, and doubt — and endomorphy.

More endomorphic pilots had higher levels of mistrust and doubt, and ectomorphic pilots had lower levels of mistrust and doubt.

Indeed, those with higher degrees of ectomorph tended to be more trusting, adaptable, and likable. Meanwhile, mesomorphs tended to be more outgoing, warmhearted, easing-going, and participants in group situations.

Confirming the results of McFarland (1953) and Clinton and Thorn (1943), pilots were predominantly mesomorphic (Adams, 1985).


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Saul Mcleod, PhD

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Educator, Researcher

Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education.

Charlotte Nickerson

Research Assistant at Harvard University

Undergraduate at Harvard University

Charlotte Nickerson is a student at Harvard University obsessed with the intersection of mental health, productivity, and design.