Aronson & Mills (1959) did an experiment to see whether people's liking for a group is influenced by the severity of initiation. They reasoned that when people willingly undergo a severe initiation in order to become a member of a group, they are motivated to think that the group membership must be worthwhile (otherwise, they would experience cognitive dissonance: why put up with severe initiation for the sake of a group membership that is worthless?) In their experiment, participants were randomly assigned to one of three treatment groups.
Group 1 had no initiation
Group 2 had a mildly embarrassing initiation (reading words related to sex out loud)
Group 3 had a severely embarrassing initiation (reading sexually explicit words and obscene words out loud).
After the initiation each person listened to a standard tape-recorded discussion among the group that they would now supposedly be invited to join; this was made to be as dull and banal as possible. Then they were asked to rate how interesting they thought the discussion was. The researchers expected that people who had undergone the most embarrassing initiation would evaluate the discussion most positively.. In the table below, a higher score represents a more positive evaluation.
Experimental Condition (Aronson & Mills)
Control Mild Severe
(no initiation) Initiation Initiation

Results of t tests between group means t p (two tailed)

4a. Were the researcher's predictions upheld? In simple language, what was found?
4b. Calculate an effect size (2) for each of these three t ratios and interpret these.

80.2 13.2 21 81.8 21.0 21 97.6 16.6 21 Mean SD Control versus Severe Mild versus Severe Control versus Mild 3.66 001 2.62 02 29 ns