The following is an excerpt of the intervention methodology. For more information, please see the full text of the article on the publisher's website or through your institution's library.

STUDY 1

Method

Participants A total of 83 Syracuse University students who were enrolled in an introductory psychology course participated [...].

Apparatus and materials Stimulus lists were constructed that consisted of 36 sentences describing a male member of group A or L performing a positive or a negative behaviour [...]. [...]

Procedure [...] Participants in the control condition (N = 21) participated in the standard distinctiveness-based illusory correlation paradigm. [...] The participants were told that they would be reading a series of sentences describing a behaviou that was performed by a particular person. [...] Finally, they were told that they would view a rather large number of statements and, as each statement appeared, they were simply to read it carefully. The computer then delivered the 36 sentences, presenting each sentence for an interval of 8s. Participants in the Before (N = 30) and After (N = 32) conditions responded to a personal preference task which identified them as members of the smaller group L. The computer presented two patterns of black and white blocks on the screen: the pattern on the left was irregular and complicated, the one on the right was regular and simple (like a checkerboard). Using the arrow keys, participants selected the one pattern that they preferred the most. After selecting the pattern they preferred the most, they received the following instructions, modeled after previous minimal subgroup manipulations: [Verbal Stimulus A]. [...] In other words, regardless of whether he or she selected the complicated pattern or the simple pattern, each participator learned that he or she was a member of group L. Participants in the Before condition performed this preference task and learned their group membership before being presented the 36 stimulus sentences about group A and group L. Participants in the After condition performed this preference task and learned their group membership after being presented the stimulus sentences. Participants next completed the assignment measure of illusory correlation. They were told that the computer would once again present each stimulus sentence with the group identification left blank. Their task was to press `A’ or `L’ when each sentence appeared, indicating whether they believed that sentence had previously been attributed to a member of group A or a member of group L. Next, all participants completed an estimation measure of illusory correlation. Specifically, one item indicated that in the sentences they had read there were 24 statements about group A, and asked them to estimate how many of those 24 described a member of group A having performed some undesirable behaviour. A second item indicated that they had read 12 statements about group L, and asked them to estimate how many of those 12 described a member of group L having performed some undesirable behaviour. Finally, participants evaluated each group on a 31-point scale, anchored by 'dislike very much’ and 'like very much’. [...]

STUDY 2

Method

Participants A total of 110 Hofstra University students who were enrolled in an introductory psychology course participated individually in the study [...].

Apparatus and materials The stimulus materials were the same as those used in Study 1. As in Study 1, all procedures and dependent measures were administered by computer.

Procedure The procedure was identical to that described for Study 1 with one addition. In addition to assigning some participants to the minority group L, some participants were assigned to the majority group A. All participants in the group membership conditions responded to the pattern preference task and they were informed that their choice indicated that they were either an Augmenter or a Leveller. The computer was programmed to identify them as belonging to the group (A or L) they had been assigned, regardless of their choice of patterns. Participants in the Before conditions performed this preference task and learned their group membership before being presented with the 36 stimulus sentences about group A and group L. Participants in the After conditions performed this preference task and learned their group membership after being presented the stimulus sentences. Thus, the design included five conditions: Control, Majority group A Before, Majority group A After, Minority group L Before, and Minority group L After.