a controversial classification of individuals based on a “clear biological affinity” between specific physiques and specific personality tendencies. According to this classification, the short, stocky pyknic type tends to be jovial and subject to mood swings; the frail asthenic type is likely to be introversive and sensitive; the muscular athletic type is usually energetic and aggressive; and the disproportioned dysplastic type presents a combination of traits but tends toward the asthenic. These tendencies were attributed to endocrine secretions. [formulated in the 1920s by German psychiatrist Ernst Kretschmer (1888–1964)]