claim: The Stanford prison experiment was an investigation into the causes of difficulties between guards and criminals.
evidence: Dimitar Dimitrov -LRB- Димитър Димитров born 20 November 1949 -RRB- is a former Bulgarian footballer who played as a midfielder .. footballer. Association football. midfielder. midfielder. In 1969 , Dimitrov joined Beroe Stara Zagora .. Beroe Stara Zagora. PFC Beroe Stara Zagora. In 1975 , he signed with CSKA Sofia .. CSKA Sofia. PFC CSKA Sofia