Introduction to Psychology
Social Psychology
Prof. Jan Lauwereyns
jan@sls.kyushu-u.ac.jp
Asch’s Experiment (1955)
Question
• How do we adjust our behavior or thinking toward
some group standard?
Procedure
1. As a participant in the study, you arrive at the experiment location in time to
take a seat at a table where five people are already seated.
Procedure
1. As a participant in the study, you arrive at the experiment location in time to
take a seat at a table where five people are already seated.
2. The experimenter asks which of three comparison lines is identical to a
standard line.
Procedure
1. As a participant in the study, you arrive at the experiment location in time to
take a seat at a table where five people are already seated.
2. The experimenter asks which of three comparison lines is identical to a
standard line.
3. You see clearly the right answer is and await your turn to say after others.
Procedure
1. As a participant in the study, you arrive at the experiment location in time to
take a seat at a table where five people are already seated.
2. The experimenter asks which of three comparison lines is identical to a
standard line.
3. You see clearly the right answer is and await your turn to say after others.
4. Your boredom with this experiment begins to show when second set of lines
proves equally easy.
Procedure
1. As a participant in the study, you arrive at the experiment location in time to
take a seat at a table where five people are already seated.
2. The experimenter asks which of three comparison lines is identical to a
standard line.
3. You see clearly the right answer is and await your turn to say after others.
4. Your boredom with this experiment begins to show when second set of lines
proves equally easy.
5. Now comes the third trial, and the correct answer seems just as clear, but the
first person gives the wrong answer.
Then the third, fourth, fifth give the same wrong answer.
What answer do you give?
Result (Percentage of error)
Control Group
⇒ Less than one percent of the time ( < 1 %)
Experimental Group
⇒ More than one third of the time ( > 33 %)
Social Influence
• Asch’s experiment
Conformity
Adjusting ones’ behavior or thinking to coincide with a
group standard
・ Under certain conditions people conform to a group’s
judgment even when it is clearly incorrect.
・ We may conform either to gain social approval
(normative social influence) or because we welcome
the information that others provide (informational
social influence).
Example of conformity: Crossing red light
Milgram experiment
• Question
People often comply with social pressure.
But how would they respond to outright
commands?
Procedure
 Come to Yale University to participate in an experiment.
Procedure
 Come to Yale University to participate in an experiment.

Get explanation that the study concerns effect of
punishment on learning.
Procedure
 Come to Yale University to participate in an experiment.

Get explanation that the study concerns effect of
punishment on learning.

You and another person draw slips to see who will be
the “teacher” and who will be the “learner”.
Procedure
 Come to Yale University to participate in an experiment.

Get explanation that the study concerns effect of
punishment on learning.

You and another person draw slips to see who will be
the “teacher” and who will be the “learner”.

You are the teacher.
Chair is wired through
the wall to an electric
shock machine.
You sit in front of the
machine, which has
switches labeled with
voltage.
Chair is wired through
the wall to an electric
shock machine.
Your Task
• To teach and then test the learner on a list of work pairs.
• You have to punish the learner for wrong answers by
delivering brief electric shocks, beginning with a switch
labeled
“15 Volts-Slight Shock”
• After each of the learner’s errors, you are to move up to the
next higher voltage.
(With each flick of a switch, light flashes,
and an electric buzzing fills the air)
Reaction from the learner
• 8th switch “120 Volts- Moderate Shock”
the learner shouts that the shocks are painful
• 10th switch “150 Volts-Strong Shock”
the learner cries and says “Get me out of here! I won’t
be in the experiment anymore! I refuse to go on!”
• After the 330-volt level
the learner refuses to answer and soon falls silent
• 450-volt level(final)
Experimenter
“Please continue. The experiment requires that you continue”
“It is absolutely essential that you continue”
“You have no other choice, you must go on”
How far do you think you would follow the
experimenter’s commands?
• Survey to people before conduction the experiment
• Prediction made by each of 40 psychiatrists whom Milgram
asked to guess the outcome
The teacher would stop after the learner first indicated pain.
Participants: Men aged 20 to 50
65% complied fully!!!
Prisoner's dilemma
• Paradigm
…to study human cooperation