Philip Zimbardo is a contemporary social psychologist best known for his Stanford Prison Study

Professional Life

Philip Zimbardo was born on March 23, 1933, in New York City. He studied at Brooklyn College and graduated in 1954 with majors in sociology, anthropology, and psychology. Zimbardo attended graduate school at Yale University, where he completed his PhD in psychology in 1959. Zimbardo spent one year teaching at Yale and seven years as an associate professor at New York University. In 1968, Zimbardo accepted a job at Stanford University as a professor of psychology.

Zimbardo developed The Stanford Shyness Clinic in 1977 to help people overcome shyness in social settings. When the clinic moved off the Stanford campus, it was renamed The Shyness Clinic; Zimbardo continues to serve there as a research consultant. Zimbardo spent decades studying and researching cult behavior and mind control, and he testified to the power of situational pressure and the events at the Abu Ghraib prison.

Zimbardo served as President of the American Psychological Association in 2002, and he has been professor emeritus at Stanford since 2003. He works with the Greater Good Science Center at UC Berkeley and is the founder and director of the Heroic Imagination Project, an organization designed to recognize and advance everyday heroism. His popular PBS series, Discovering Psychology, teaches basic psychological principles and theories to a lay audience. 

Contribution to Psychology

Zimbardo has spent most of his career researching how and why people are transformed in certain situations so that they behave in unexpected ways, such as when a good person commits an atrocious act, or an intelligent person does something irrational. Zimbardo has also researched shyness, motivation, and human perspectives on time.

Zimbardo designed the Stanford Prison Experiment to determine what the result would be when one group was granted authority over another group. In the 1971 study, Zimbardo assigned 24 college students with the roles of guards or prisoners in a mock prison on the Stanford grounds. Though the study was scheduled to last two weeks, over the course of six days, the prisoners developed unique behaviors that mimicked those of real prisoners, including rioting, rebellion, and even depression and rage. The prison guards, who were given clear instructions as to which tactics they were allowed to use, quickly began exceeding the limitations of punishment and degradation. The observing psychologists noticed that many of the prison guards used sadistic and even torturous behaviors to gain control over the prisoners, even when unwarranted. The prisoners believed that they were real prisoners, and several were severely emotionally traumatized. The experiment was terminated early as a result.

The ethics of the study are still widely debated today. Many researchers point to the study as evidence of the effects of incarceration, as an indication of the negative effects absolute control can have on a person's conscience, or as an explanation of groupthink and cult behavior. Zimbardo expanded on the results of the experiment, drawing parallels to Abu Ghraib prison conditions in his 2007 book, The Lucifer Effect: Understanding How Good People Turn Evil.

The Zimbardo Time Perspective Inventory (ZTPI) was designed by Zimbardo to measure a person’s perspective on the past, present, and future. The ZTPI test measures five attitudes toward time: past-negative, past-positive, present-fatalistic, present-hedonistic, and future. Zimbardo outlined his theories in The Time Paradox: The New Psychology of Time That Will Change Your Life. Zimbardo believes that our lives are shaped by our perspective of time and that a series of paradoxes influence both personal and cultural behavior:

  • Paradox 1. People are typically unaware of the powerful effect time has on their feelings, thoughts, and actions.
  • Paradox 2. A person’s attitudes toward time can be beneficial, unless any one attitude persists over others.
  • Paradox 3. A person’s time perspective is shaped by personal experience, though these attitudes also form a collective, cultural perspective that shapes a nation.

Recently, Zimbardo began developing the concept of social intensity syndrome, with colleagues Sarah Brunskill and Anthony Ferreras. The theory is designed to explain the culture of the military. Zimbardo and his colleagues claim that the intense environment of the military can lead to hypermasculinized behavior that causes an extreme endorphin high. 

Selected works by Philip Zimbardo

  • The Cognitive Control of Motivation (1969)
  • Influencing Attitudes and Changing Behavior (with E. Ebbesen, 1969)
  • Shyness: What It Is, What To Do About It (1977)
  • The Lucifer Effect: Understanding How Good People Turn Evil (2007)
  • The Time Paradox: The New Psychology of Time That Will Change Your Life (with J. Boyd, 2008)
  • The Demise of Guys: Why Boys Are Struggling and What We Can Do about It (2012)


  1. Maslach, C. (2000, Sep). Emperor of the edge. Psychology Today, 33, 34-41. Retrieved from
  2. Philip G. Zimbardo. (2008). Contemporary Authors Online. Retrieved from