why do you think Dr.Spivey's opinion of mcmurphy has changed

I think McMurphy is charismatic enough to influence Spivey. Spivey has wondered if McMurphy is really insane of merely faking it. In any case, he seems to seek McMurphy's approval.McMurphy uses him as his institutional defense on the ward, convincing him to open the tub room and to chaperone the patients on the fishing trip. Nurse Ratched, meanwhile, uses him to champion her authoritarian policies to discipline rebellious inmates.