Asch, S. E., Effects of Group Pressure Upon the Modification and Distortion
of Judgements. In H. Guetzkow (ed.) Groups, Leadership, and Men, 1951.
This is a summary of the famous Asch experiment where subjects were placed
with a group of confederates who gave different measurements of a line than
was reality. Asch measured whether the subject would modify their interpretation
based on the majority opinion.
The test objective was to study "the social and personal conditions
that induce individuals to resit or to yield to group pressures when the
latter are perceived to be contrary to fact.
A group of eight individuals (one subject and seven confederates) sat in
a room and verbally stated which of three unequal lines matched a given
line. The subject was seated so that he made his verbal judgement last.
In most cases the confederates and subject agreed, but in certain cases
the confederates all agreed on a wrong answer.
The "majority effect" was measured as the % of responses that
erroneously conformed to the majority. They also tried to ascertain whether
the subject was aware of the majority effect on him and why they acceded
to group opinion. They also watched the reaction of the subject when the
experiment was revealed. All subjects and confederates were male college
About one third of the responses conformed to the erroneous majority (compared
to almost no errors in the control group). Some subjects always defied
the group, some always went along with them. 25% were completely independent,
33% were more than half with the erroneous majority. Some were completely
confident throughout, some were disoriented and confused.
The independent subjects were categorized as 1) confident in their differences
2)withdrawn and 3)considerable tension and doubt, but adhere to their views
The yielding subjects could be categorized as 1)distorted perception who
believed the majority estimates as correct 2)distortionof judgement --
they believe their own perceptions are inaccurate (they have primary doubt
and lack of confidence). 3)Distortion of action -- they believe the group
is wrong but conform to avoid being different.
The effect of "ununanimous" majorities
In one variation, they added one more subject at position 4. This reduced
the % of errors from 32% to 10%. In another variation, having one confederate
give right answers throughout reduced it to 5.5%.
This shows that even a minimal amount of dissenting support is enough to
give people confidence in their opinions against the majority. The researchers
found that even a unanimous majority of only three is better than 8 with
The effect of withdrawal of a "true partner"
Surprisingly, if a confederate who was answering correctly "defects"
back to the majority halfway through, the % of with-the-majority responses
returns from 5.5 to 28.5%.
The effect of late arrival of a "true partner".
If a confederate answering with the majority changes to answering truly,
the rate of majority response drops down to 8.5%.
The effect of a "compromise partner" (who answered with
majority sometimes, correctly sometimes).
This reduced the rate of majority response but not significantly.
The effect of majority size.
They varied the number of confederates from 1,2,3,4,8, and 10-15 persons.
There was no majority effect with only one other person. There was a small
change with two people, and nearly the full amount with three confederates.
There was little change above three confederates.
Interestingly, in one condition they put 16 naive persons in a room and
had two confedrates give wrong answers. The group responded with amusement
at their errors.
They also found that the degree of independence increases with the deviation
of the majority from the truth. However, even big differenes didn't create
complete independence. They also concur with other researchers that the
effect of majority opinion increases with decreased clarity in a situation.