Canada’s The Daily Gleaner has a brief but revealing insight into the understanding of juvenile crime and delinquent behaviour in the 1920s.
Obviously the cultural standards of the day were different, so some behaviours considered ‘delinquent’ then were not be considered so now, and vice versa.
However, it is also clear from the piece that theories of how delinquency came about were influenced by very different sets of assumptions.
Prior to the emergence and expansion of psychiatry, moral and eugenic discourses dominated the understanding of juveniles and their treatment. However, Toronto Mayor Howland and other 19th-century reformers believed “allowing youth to go to the devil was a sheer waste.”
They believed there was no “such thing as a youth being really criminal at heart,” and that all deviant actions were just “surface depravity.”
Children were considered to be the product of their surroundings, and if a delinquent grew up in idleness and crime, that is what any child would be in a similar situation.
Previously, the dominant explanation for juvenile deviance was a ‘defective mind’ due to an inherited degenerate constitution. Famous at the time were life histories of degenerate families, with their poverty, prostitution, alcoholism and incest.
The brief article also mentions case reports of the time with a short excerpt which seems nothing short of jaw-dropping from a modern perspective:
Amanda, for example, had become “impudent of late” with a tendency to become “foxy and cunning.” Physical examination of her hymen showed she “had been immoral,” so she was found guilty of vagrancy and sent to the home for girls.
When Amanda was asked by a social worker about her life goals, she said she wanted to be an actress, and the psychiatrist was appalled. He suggested that a better occupation would be milliner, with release conditional on her acceptance.
Link to psychology and delinquency in the 1920s (via @jonmsutton).
Mind Hacks 
http://www.egs.edu/ Larry Rickels lecturing for the students of the European Graduate School EGS. The lecture focuses on psychoanalysis, treatment, torture and electric shocks. European Graduate School, EGS Media and Communications Program Studies Department, Saas-Fee, Switzerland, Europe
If you liked this peek into history, you might enjoy “Pathological Lying, Accusation, and Swindling ā A Study in Forensic Psychology.” Published in 1915, it’s a detailed description of several young “pathological liars” and the “constitutional degeneracy” and rough situations that apparently created them. It’s available in audio through Librivox and as text through Project Gutenberg. It was fascinating.
This may be Toronto (same place where black musicians were denied Union cards whereas visiting US musicians with affiliate cards could play the clubs, but I digress) whereas possibly concurrent to this going on in Ontario, over in Winnipeg, and perhaps as late as the 1940’s, my parents would tell of public whippings, claiming these very quickly and effectively put an immediate end to an infamous Doo-Drop gang of juvenile delinquints.