In the study of personality, trait-centred explanations have not always prevailed. At the beginning of the last century several proposals for somatic explanations began to appear, such as Kretschemer’s biotype, which descend from a way of understanding psychology that dates back to the times of Hippocrates.

Next we see Kretschemer’s theory and how he relates the different body constitutions to attributes of human temperament.

Kretschemer’s constitutional model

Biological theories of personality start from the idea that human behaviour depends basically on the physical characteristics of the organism, and not so much on the variables related to the context in which we live. These theories have their roots in the first steps of the Greek medicine, but it is normal that their approaches are biological.

This constitutional model, in psychiatry, is represented by Kretschemer. Ernst Kretschemer, a German psychiatrist, was interested in the problems of physical constitution and how the vegetative and endocrine mechanisms determine it. He theorized that these maintained some kind of relationship with the formation of each person’s temperament. In addition, he worked to unravel the relationship between a person’s character, his constitution, and psychiatric syndromes.

The fruit of these efforts was reflected in his constitutional model of personality. For Kretschmer, the constitution is composed of all the characteristics with which an individual is born . This includes the genotype that interacts with the environment to produce a phenotype. This phenotype manifests itself in three ways: constitution, character and temperament. Since they are manifestations of the same phenotype, it is theorized that they are closely related to each other.

Based on clinical observations and anthropometric research, Kretschmer describes a constitutional typology in which he defends the existence of four main types :

1. Leptosomal

Kretschmer’s theory describes the leptosomal as a person with long arms, a high neck and a receding chin. A kind of Don Quixote in both physique and temperament. The leptosomal is shy, hypersensitive, eccentric and tends to live in his own fantasy world .

2. Picnic

This guy is described as a chubby, pot-bellied person. He has a spherical head and a round face, with a short neck and limbs and short, thick fingers. Taking up again the quixotic characteristics of the leptosome, the picnic would resemble Sancho Panza: warm, outgoing, cheerful, good by nature , practical and down-to-earth.

3. Athletic

The athlete has powerful muscles, hard and strong bones, broad shoulders and a narrow waist. It corresponds to a type of physique similar to that of Superman. The temperament of individuals with an athletic type is associated with ruthlessness, emotional coldness and aggressiveness . They are highly competitive individuals.

4. Dysplastic

This is the weirdest constitutional guy. All the body proportions are unbalanced and, accordingly, so is his temperament . This type, according to Kretschmer’s observations, is associated with endocrine disorders and, very often, with severe schizophrenia.

How do you interpret this personality classification?

These constitutions are not taxonomical, but must be understood as dimensions. According to Kretschmer, most people have an amalgamation of types and each is situated closer to one end in one type and further away in another. This is why not all people show a profile that corresponds exactly to one type or another, only that they are closer or closer depending on their phenotype.

Following this line, he investigated through experimental methodology what individual differences existed between the different types. Kretschmer tested the variability of characteristics such as sensitivity to colour and shape, concept formation or psychomotor speed in the different constitutional types.

Reviews of Kretschmer’s model

Naturally, no model is free from criticism and Kretschmer’s biotypes are no exception . It is to be expected that a model that drinks directly from such unscientific ideas as the moods of Hippocrates has serious shortcomings in its validity.

On the one hand, Kretschmer’s model sins of being not very exhaustive in its description . He establishes four categories that vaguely and imprecisely describe four stereotypical profiles. These profiles are rigid and immovable, generating two important problems: those characteristics that are not described in the model are left unexplained, and it does not offer a flexible explanation for those cases that do not fit the model.

This is due, in part, to the fact that the sample Kretschmer used to develop his model were psychiatric patients, primarily schizophrenics, and males. The model, ignoring the problems of internal consistency and coherence, cannot be extrapolated to the general population .

On the other hand, although Kretschmer’s biotypes constitute an interesting antecedent of rupture with the psychiatric tradition by considering that normality and illness do not have a clear limit but are a matter of degree, it offers an explanation of personality through a circular reasoning. Kretschmer does not rigorously ground the theory, but rather the theory grounds itself.

In short, although Kretschmer’s effort to modernize the relationship between body and personality is laudable and not without a scientific spirit, his theory remains a vestige of an outdated way of understanding personality.