In one massive experiment, potentially delinquent boys were assigned to a 5-year treatment program that included professional counseling and family assistance. many years later, joan mccord's investigation of this program's effectiveness revealed that a clients who received the special treatment subsequently had fewer incidents of juvenile delinquency. b clients typically underestimated the truly positive effects of this program on their own lives. c only the therapists who were involved in the program could accurately gauge its effectiveness. d clients' accounts of the program's effectiveness were often misleading and overly positive.