In the grip of social
influence
Phillip Zimbardo: Is the dispositional hypothesis true?
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
 Participants chosen to be as “normal” and
homogeneous as possible
 “Arrested” by the police
 Scheduled to spend 2 weeks in a simulated prison
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
 Participants chosen to be as “normal” and
homogeneous as possible
 “Arrested” by the police
 Scheduled to spend 2 weeks in a simulated prison
 The experiment was stopped after 6 days because it
“went too far”
 Arguably the most famous “experiment” in
psychology
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
 “Guards” asked to “maintain the reasonable degree of order
within the prison necessary for its effective functioning”
 “Absence of specific hypotheses”
 Everybody was free to leave but “couldn’t” because of
the identification with their role (“guards” enjoyed their
position; “prisoners”accepted their position passively)
 “Guards” devised the techniques of oppression
spontaneously, even though they “could have behaved
in any way they liked”
 Four prisoners had to be released because of severe
stress reactions
Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a
simulated prison. International Journal of Criminology & Penology, 1, 69-97.
Zimbardo’s interpretation of prisoners’ behaviour:
 Loss of personal identity (deindividuation) = uniforms;
numbers instead of names
 Arbitrary control leading to learned helplessness
 Dependency and emasculation
Original recordings revealed + interviews with participants:
 Participants were actually told they were not allowed to
leave.
 During the orientation meeting, the “guards” reminded that
torture other than physical is permitted.
 Techniques of oppression devised by Zimbardo’s student
assistant, whose project also inspired the study.
 Participants admitted they acted in ways they thought
would please the experimenters (= the goal was to act this
way).
 Famous “nervous breakdown” was actually simulated.
“We cannot physically abuse or torture them,” Zimbardo told them, in recordings
first released a decade and a half after the experiment. “We can create boredom.
We can create a sense of frustration. We can create fear in them, to some
degree… We have total power in the situation. They have none.”
Once the simulation got underway, Jaffe explicitly corrected guards who weren’t
acting tough enough, fostering exactly the pathological behavior that
Zimbardo would later claim had arisen organically. “The guards have to
know that every guard is going to be what we call a tough guard,” Jaffe told one
such guard. “[H]opefully what will come out of this study is some very
serious recommendations for reform… so that we can get on the media
and into the press with it, and say ‘Now look at what this is really
about.’ … [T]ry and react as you picture the pigs reacting.” Though most
guards gave lackluster performances, some even going out of their way to do
small favors for the prisoners, one in particular rose to the challenge: Dave
Eshleman, whom prisoners nicknamed “John Wayne” for his Southern accent
and inventive cruelty. But Eshleman, who had studied acting throughout high
school and college, has always admitted that his accent was just as fake as Korpi’s
breakdown. His overarching goal, as he told me in an interview, was simply to
help the experiment succeed. ... After the experiment ended, Zimbardo singled
him out and thanked him. “As I was walking down the hall,” Eshleman
recalled, “he made it a point to come and let me know what a great job
I’d done. I actually felt like I had accomplished something good because I
had contributed in some way to the understanding of human nature.”
 Zimbardo’s claim that
people passively “slip”
into roles not confirmed –
guards passive and
“powerless”in this study,
initiative taken by
prisoners
 Social identity theory –
depends on group
identification and success
of the group
 However, this was a TV
show… what does it
mean?
Reicher, S., & Haslam, S. A. (2006). Rethinking the psychology of tyranny:
The BBC prison study. British Journal of Social Psychology, 45(1), 1-40.
Stanley Milgram: How far will people go with their
obedience to authority?
Milgram, S. (1963). Behavioral study of obedience. The Journal of Abnormal and
Social Psychology, 67(4), 371-378.
The machine: 30 V increasing all the way up to 450 V: "slight
shock"  "moderate shock"  "danger: severe shock" 
"XXX“
Prods:
 "Please continue."
 "The experiment requires that you continue."
 "It is absolutely essential that you continue."
 "You have no other choice, you must go on.“
Milgram, S. (1963). Behavioral study of obedience. The Journal of Abnormal and
Social Psychology, 67(4), 371-378.
FURTHER EXPERIMENTS – AUDIO:
 75-135 volts: “Ugh!!!”
 150 volts: “Ugh!!! Experimenter! That's all. Get me out of here. I
told you I had heart trouble. My heart's starting to bother me
now. Get me out of here, please. My heart's starting to bother
me. I refuse to go on. Let me out.”
 165-255 volts: (Shouting) “Ugh!!! Let me out!”
 270-285 volts (Screaming) “Let me out of here. Let me out of
here. Let me out of here. Let me out. Do you hear? Let me out of
here.”
 300-315 volts: (Screaming) “I absolutely refuse to answer any
more. Get me out of here. You can't hold me here. Get me out.
Get me out of here.”
 330 volts: (Intense and prolonged screaming) “Let me out of here.
Let me out of here. My heart's bothering me. Let me out, I tell
you. (Hysterically) Let me out of here. Let me out of here. You
have no right to hold me here. Let me out! Let me out! Let me
out! Let me out of here! Let me out. Let me out.”
 345-450 volts: (Silence)
 The experiment was terminated by the experimenter after 3
shocks at 450 volts
Original documents revealed + interviews with participants:
 Experimenter bias: Prodding was extended, did not follow
protocol, and resembled bullying: “The experimenter’s
answers to the teacher’s queries reveal that the experimenter had
defined his role as doing whatever was necessary to get the teacher
to continue giving the shocks.”
 Serious ethical issues and selecetive reporting: Participants
not debriefed properly (despite reports caliming otherwise);
“secret” unreported studies conducted (shocking a close
friend/relative – 85% disobedience)
 Underestimated failed manipulation: Many of those who
“went all the way” did not believe the electric shocks were
real – Milgram knew but did not report.
r = .00
r = .70
WHY, it’s my data, I can
use it whichever way I
want...
 Confirmation bias („Experimenter Effect“) –
overstate evidence supporting my theory and
neglecting evidence against my theory
 Congruence bias – looking for evidence to support my
hypothesis rather than test alternative hypothesis
 Observer-expectancy effect – subconscious
manipulation of experimental situation in order to
achieve the desired effect
 Hindsight bias – modifying or creating hypotheses
after results are known, „I knew it all along“ fallacy
 Availability heuristic – only considering “here-andnow
evidence”, not the entire body of research
 Publication bias – non-significant results are seen as
unimportant, hence unpublishable
Mind the principles of inductive reasoning…
 One research study is never enough to draw
conclusions.
 Hypotheses have to be formulated before
conducting new research, should be based on
previously well-established observations.
 Finding plausible explanations for what already
happened is easy – this is not science!!! These
explanations have to be tested as hypotheses, and
alterantive explanations have to be tested as well.
 All results (postive, negative and inconclusive) have
to be reported.
 No adjustments in data or hypotheses can be made
post-hoc.
 Theory has to be formulated very carefully so that
there are no logical errors or unfounded
assumptions.
Asch, S. E. (1955). Opinions and social pressure. Scientific American, 193(5), 31-
35.
Group influence increased with:
 Larger group size (only up to 3 people)
 Subject started to conform from the beginning
 No other “dissident” in the group
 Partner suddenly joins the majority
 Actual difference in line length…?
Darley, J. M., & Latané, B. (1968). Bystander intervention in emergencies: Diffusion of
responsibility. Journal of Personality and Social Psychology, 8(4p1), 377-383.
Diffusion of responsibility – expectation that help will
come from elsewhere
 Festinger & Carlsmith, 1959
Group A:
 Asked to do a tedious
task for more than 1 h
 Asked to do a „favour“
for the experiementer:
 Persuade next participant
that the task was
interesting
Festinger, L., & Carlsmith, J. M. (1959). Cognitive consequences of forced
compliance. The Journal of Abnormal and Social Psychology, 58(2), 203-210.
Group B:
 Asked to do a tedious
task for more than 1 h
 Asked to do a „favour“
for the experiementer:
 Persuade next participant
that the task was
interesting
Group A:
 Asked to do a tedious
task for more than 1 h
 Asked to do a „favour“
for the experiementer:
 Persuade next participant
that the task was
interesting
 Paid $ 20
Festinger, L., & Carlsmith, J. M. (1959). Cognitive consequences of forced
compliance. The Journal of Abnormal and Social Psychology, 58(2), 203-210.
Group B:
 Asked to do a tedious
task for more than 1 h
 Asked to do a „favour“
for the experiementer:
 Persuade next participant
that the task was
interesting
 Paid $ 1
Ratings of task after payment:
Festinger, L., & Carlsmith, J. M. (1959). Cognitive consequences of forced
compliance. The Journal of Abnormal and Social Psychology, 58(2), 203-210.
Enjoyable?
Again?
Control Group
$ 20
$ 1
Aronson, E., & Mills, J. (1959). The effect of severity of initiation on liking for
a group. The Journal of Abnormal and Social Psychology, 59(2), 177-181.
Group A:
 Ready to join a discussion
group
 Initiation: Reading
educational sex-related
text
 Asked to rate
conversation of the group
they joined
Group B:
 Ready to join a discussion
group
 Initiation: Reading
embarrassing
pornographic text
 Asked to rate
conversation of the group
they joined
Ratings of recorded (boring) conversation:
Aronson, E., & Mills, J. (1959). The effect of severity of initiation on liking for
a group. The Journal of Abnormal and Social Psychology, 59(2), 177-181.
Interesting discussion?
Control Group
Low
embarrassment
High
embarrassment
 When our actions are in conflict (dissonance) with our
beliefs, values, or primary motives we are inclined to
change either the belief or the behaviour
 Which of these changes depends on which one is
easier to change (e.g. we cannot change our past
actions  we tend to change our belief)
 Other behaviours are difficult to change: bad habits,
impulsive behaviour, conforming to group behaviour…
Less or more…?
Social loafing
 Situations of cooperation
 Coordination loss (partly)
 Mitovation loss = believe
my contribution is
dispensable; my
contribution is invisible
 Comparison with others
Social facilitation
 Situations of coaction and
competition
 Self-presentation
 Increased arousal
 Feedback – comparison
 Negative influence on
people with low selfesteem
and social anxiety
Thank you!