Some participants developed their roles as the guards and enforced authoritarian measures and ultimately subjected some prisoners to psychological torture. Many of the prisoners passively accepted psychological abuse and, by the guards' request, actively harassed other prisoners who tried to stop it. Zimbardo, in his role as the superintendent, allowed abuse to continue.[4][5] Two of the prisoners left mid-experiment, and the whole exercise was abandoned after six days following the objections of graduate student Christina Maslach, whom Zimbardo was dating (and later married).