Kretschmer has classified the persons in which one of the following main types?

German psychiatrist Ernst Kretschmer in his book 'Physique and Character' that was published in 1921, classified the persons in following typesPyknic 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.