In order to create a new prison, Zimbardo transformed the Stanford University’s basement into a fake prison. Then, he create an ad in the paper in order for him to receive participants for his research. Each person that signed up for the study had to take tests in order to eliminate those who had a criminal record, psychology issues, or medically disabilities. Zimbardo ended up with  twenty-one males who were in college. The participants within the study were paid fifteen dollars for each day they were in the experiment. Zimbardo randomly assigned which participants received the role of guard and prisoner. He decided to have ten of his participants be prisoners and eleven of the participants be guards. Three guards would be on duty and switch every eight hours. There were three prisoners within a cell, and there was a solitary confinement room for participants whenever the guards decided that they had misconduct. 
In order to really capture the essence of criminals, Zimbardo had the ten participants who were chosen as criminals to be arrested randomly, and booked. The prisoners were then driven to the “prison” while blindfolded. When the “prisoners” were in the prison, they had their personal belongs taken away, and were stripped. Then, they were given a uniform that each had different numbers as a way to Id themselves while keeping them unacknowledged. Prisoners were only allowed to call each other by their number, and not by any real names. The uniforms that the prisoners were given was a smock and a nylon cap. The guards were dressed in the same khaki uniforms as each other and given a whistle and police night club. Guards were instructed to have black sunglasses on them in order to not have eye contact with the prisoners. Essentially, the only rules that the guards had was that they was not allowed to enact physical violence on the prisoners. Other then that, the guards were allowed to do whatever they wanted in order to ensure order and respect within the prison. 
The start of police brutality commenced when the guards started to hassle the prisoners by blowing the whistles in order to perform counts. The original reason was these counts were to see if all the prisoners were present and knew the rules and ID numbers. Then the guards insulted prisoners and ordered them to do tedious duties like doing push-ups in order to exercise their authority. The prisoners decided to rebel against the guards by removing their IDs and blocking themselves inside their cells. The guards determined to stop the rebellion by extinguishing the prisoners and stripping them naked. After this rebellion, the prisoners and guards had a tumultuous relationship. The guards harassed the prisoners in order to demonstrate who was in control and the prisoners listened to them because they relied on them for food and other necessities. Ironically, the more submissive the prisoners became, the more hostile the guards acted. 
In order to make the prison seem even more real, the prisoners had visitation rights. The families and friends of prisoners came to visit them. Afterwards, prisoners decided to escape the prison; however the escape plan did not work out well. Soon, several prisoners began to have mental breakdowns, and to be released from the experiment. Zimbardo intended to have the experiment last for two weeks; however, he had to stop the research after the sixth day.
The results of this study demonstrated that people will integrate into the social roles that they are predicted to portray almost immediately. During the study, the guards were savage to the prisoners meanwhile the prisoners were submissive towards the guards. Some prisoners even had emotional breakdowns. Before the study, the “guards” showed no signs of brutal behavior; however, it seems that the setting of a prison environment created the viscous personalities of the guards. Prisoners who were chosen specially for the strength of their emotional states had mental breakdowns. Therefore, to answer ZImbardo’s research question, the characteristics of prisoners and guards were due to the environment rather than their dispositions. Zimbardo explains the reasoning behind the prisoners’ and guards’ actions from the theories of learned helplessness and  deindividuation. He learned that the prisoners most likely felt helpless against the guards and that anything they did would be of little use, so they submitted to everything the guards ordered them to do. The guards’ actions are explained by deindividuation in that they saw themselves as one rather than individuals. This means that the guards actions were not a personal fault of theirs, but rather the groups fault as a whole. 
Zimbardo’s Prison Experiment was an important contribution to the field of psychology because it led to a change in the ethical guidelines ran by the APA. Before the Stanford Prison Experiment, technically ZImbardo followed all of the ethical guidelines; however, after the study the APA decided that the participants had received detrimental treatment. In order to ensure that no future participants would be harmed in an experiment, the APA currently has research studies be analyzed before being performed. The board of people who decide whether a research study is safe or not can alter the study in order to ensure that no psychological or physical damage is done. Zimbardo’s research gave the psychology field more of an understanding about the behavior of humans and how groupthink can negatively impact people.