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.

Method

Subjects Four hundred seventy-four students (234 men and 240 women) enrolled in the general psychology course participated in partial fulfillment of their research-readings or participation requirement. [...]

Procedure

Subgroup formation. In each session, two 3-person groups were assigned ostensibly to two different experiments located in different areas within the laboratory complex. Each group was unaware of the other group's existence. [...] As they entered, the experimenter asked each person to attach these identification tags to their clothing and to sit according to their color-coded identity, which was matched by a color-coded placemat on the group's table. [...] Following the 3-person group discussion focused on the winter survival problem, subjects were informed of their subsequent contact with the other group, which would take place soon in a larger room within the laboratory complex.

Cooperation manipulation. Overall, three aspects of intergroup cooperation were varied simultaneously: interaction, a common problem requiring a consensus solution, and common fate. In the no-cooperation condition, none of these features were present. Instead, the members of both groups were brought together and exposed to a taperecorded discussion of two other groups reaching consensus on the winter survival problem. Following exposure to the 6-min recording, each participant recorded an evaluation of the effectiveness of the prerecorded group's solution. In the cooperation condition, all three features of cooperation were present. Specifically, the two groups were interdependent in that they discussed the winter survival problem and reached a single consensus solution that if effective (in terms of an absolute standard determined by the experimenters) would qualify the 6 participants for entry into a lottery at the end of the semester during which they could share a $60 prize (i.e., $10 per person). No feedback about the group's effectiveness was given during the experimental session.

Representation manipulation (one group vs. two groups). [...] To induce these groups to have a one-group representation of the aggregate during contact (independent of the presence or absence of cooperative interaction), the members of both groups were seated in same colored chairs at a single hexagonal table in an integrated seating pattern (ABABAB). Subsequent instructions emphasized their common identity as students at the same university and instructed them all to wear the same available T-shirts displaying the name of their university. Also, an experimenter assigned the members of both groups a new single name to represent all 6 people [...]. [...] In addition, all participants were asked to hold on to a rope placed in the center of the table, ostensibly to keep all participants within camera range. Last, because in the cooperation conditions, the derived consensus solution would function as a tangible product to represent all 6 participants, subjects in the no-cooperation one-group condition were instructed to estimate [...] the 6 current participants' average evaluative rating of the prerecorded group's solution. [...] In the two-groups condition, the members of each 3-person group sat at different tables (36 in. apart) in a segregated seating pattern (AAABBB), in different colored chairs (one group used red chairs; the other group used yellow chairs), during exposure to instructions that did not mention their common university identity or require them to wear university T-shirts. [...] Instead, each participant in the no-cooperation/two-groups condition separately recorded his or her own evaluation of the effectiveness of the prerecorded group's discussion. [...]

Measures. Following the experimental manipulations, the participants were given a postexperimental questionnaire containing items which asked about (a) their conceptual representations of the aggregate [...] (b) their ratings of how much it felt like they were cooperating and competing with each other during the contact period; and (c) their evaluative ratings (1-7) of each participant (except for themselves) regarding how much they liked each of the others, as well as their ratings of each person's honesty, cooperativeness, and similarity to themselves. Separate in-group and out-group ratings were constructed for each person and then averaged for each 6-person group. [...]