Per Henrik Nils Sjöbring, born July 9, 1879 in Aringsås, Sweden, dead February 19, 1956, was a Swedish physician and professor of psychiatry.
Sjöbring received his doctorate in 1913 at Uppsala University and was a professor of psychiatry at the University of Lund 1930-1944. He has become best known for his variables for description of personality types. His so-called constitution factors (known as Sjöbring's theory of constitution) are called:
validity (psychic energy)
stability (balance in keynote)
solidity (firmness, tardiness, tenacity)
By means of these variables, all people can be categorized as either normal, super- or sub-; for instance subcapable (unintelligent), subvalid (lack of psychic energy), normosolid, superstable, and so on.