One might argue that all life experiences build character and problem solving skills, but being backed by a scientific study makes a theory stronger. I hope that going to prison lowers confidence though.
I would think being in a gang would weaken those skills since they tend to value loyalty to the gang and discourage too much individuality. And using violence as a problem solving skill isn't really embraced in today's society.
Could an argument be made that going to prison also builds character, confidence, and problem solving skills? Or being in a gang?