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Experiment 1

In Experiment 1, we examined in a laboratory setting whether the exposure to a poster highlighting differences among members of an out-group reliably influenced participants’ level of prejudice and discrimination.

Participants A total of 49 female undergraduate students at the University of Clermont-Ferrand, France, participated [...]. Accordingly, the data from 43 participants were analyzed.

Dependent measures Participants completed a stereotypicality measure, consisting of five positive (e.g., cheerful, original) and five negative (e.g., aggressive, insolent) attributes that, based on elaborate pretesting, are all seen as stereotypic of Arabs in France. Participants judged the extent to which each attribute was descriptive of a typical Arab individual on continuous rating scales with endpoints labeled “is not at all descriptive” and “is very descriptive.” [...] Prejudice toward Arabs was measured with the Modern Racism Scale, translated to French [...]. The scale consists of 15 items [...]. Participants indicated their agreement or disagreement on continuous ratings scales with endpoints labeled “I disagree entirely” and “I agree entirely.” [...] Participants also filled out a 6-item version of Adorno, Frenkel-Brunswik, Levinson, and Sanford (1950) ethnocentrism scale [...]. Discrimination was measured by asking participants whether they would be willing to spend time with members of the out-group. More specifically, participants were informed that an Arab interest group in town was looking for volunteers and were asked whether they would be willing to participate in meetings during which Arab and French individuals talk to each other. Participants indicated whether they agreed to volunteer for this association. If they agreed, they were asked how much time they would be willing to devote to the planned meetings. [...]

Procedure Participants were run individually. Upon their arrival at the laboratory, they were greeted by a female experimenter who explained that the previous participant was still working in the experimental room, and that they would have to sit for a few minutes in a waiting room. Six posters [...] were displayed on the walls of the waiting room. Five of these posters encouraged people to modify their behavior (e.g., to stop smoking, not to drive under the influence of alcohol, recycle more). The sixth poster varied according to experimental condition. In the heterogeneous condition, participants were exposed to the poster “What makes us the same—is that we are all different”whereas in the control condition, they saw a poster encouraging people to eat more fruits and vegetables. After a few minutes, the experimenter returned to the waiting room and explained that the experiment was about measuring participants’ attention and speed. She then suggested that participants complete the first task in the waiting room in order to save time. This task was in fact a distracter task included to make the cover story more credible. Participants completed Zazzo’s (1972) “Cancellation Task,” which consists of locating and crossing off all instances of two target signs that were presented among a large number of distracter signs in a given amount of time. [...] Participants then filled out the stereotyping scale, the prejudice scale, and the ethnocentrism scale. Finally, participants completed the task measuring discrimination against Arabs (willingness to volunteer for an Arab interest group). [...]

Experiment 2

The purpose of Experiment 2 was to extend the findings of the previous experiment to a field setting in which participants’ exposure to the poster was even more unobtrusive than in Experiment 1. [...]

Participants Participants were 50 undergraduate students at the University of Clermont-Ferrand, France, including 7 men and 43 women. The average age was M = 19.52, SD = 2.10. [...]

Procedure [...] A female experimenter who did not appear to belong to an ethnic minority group approached potential participants and asked whether they would volunteer to participate in a short experiment. If the individuals agreed, she gave them first the questionnaire with the perceived variability measures and then, once they had handed back the filled-in questionnaire, she gave them a second questionnaire that contained the 15 items of the Modern Racism Scale. The procedure for participants in the heterogeneous condition was the same, with the only difference that the poster attracting the viewers’ attention on the diversity of Arabs had been put on the inside of the library door. [...]

Experiment 3

[...] In Experiment 3, we examined the attitudes of French high school students toward Arab people. [...]

Participants One thousand twelve students (485 boys and 527 girls) from eight high schools were tested. Their mean age was 16 years and 9 months (SD = 1.29 year). The total number of participating classes was 48. The average number of classes that were tested in each school was 6. [...]

Experimental design We implemented a matched randomized experimental design. After we had the final list of schools agreeing to participate in the experiment, we formed pairs of schools so that the two schools in the same pair were as similar as possible on a number of sociological dimensions. These dimensions included the size of the student body, the social status of the students, the ethnic composition of the school, and the environment in which the school was located (rural versus urban). Once schools were grouped into pairs, we randomly assigned one school in each pair to the treatment condition (poster) and other to the control condition.

Procedure The study took place over a period of 5 weeks. In the first week, posters attracting the viewers’ attention to the diversity of Arabs were put on the classroom walls in the treatment schools. Another poster was put on the door outside of the school principal’s office. The poster was identical to that used in Experiments 1 and 2, except that it contained only pictures of young Arab individuals and not, as the previous version, pictures of Arabs of all ages. Two weeks later, the posters were taken down. Posters were put up and removed outside of class hours. During the fifth week, a female experimenter visited the participating classroom and asked students to participate in a short study. Students completed a questionnaire measuring perceived variability and attitudes toward Arabs. At the end of the questionnaire, participants indicated if they recalled having seen the poster or not. The students in the control schools were not exposed to the poster. They completed the perceived variability and attitudes questionnaire at the same time as the students in the treatment condition. [...]

Dependent measures Participants made their responses on continuous rating scales [...]. The questionnaire included measures of perceived variability, in-group bias, social distance, prejudice, and discrimination [...]. The order of the two target groups (i.e., French and Arab) was counterbalanced for the measures of perceived variability and in-group bias.

Perceived variability This construct was measured by two questions. Participants indicated the extent to which they thought Arabs [the French] (a) were different from each other (on a scale with endpoints labeled “not at all different” and “very different”), and (b) were similar to each other (on a scale labeled “not at all similar” and “very similar”). [...]

In-group bias The in-group bias measure consisted of having participants rate the extent to which the French and the Arabs possessed four traits (egoistic, aggressive, hardworking, and cheerful). [...]

Social distance The social distance measure was based on previous research and contained one positive item [...] and two negative items [...]. [...]

Prejudice Participants’ prejudice level was evaluated by the Modern Racism Scale [...]. Four items were positive and the four items were negative. [...]

Discrimination In order to assess discrimination, participants were asked whether they wanted their name to appear on a web petition in support of reduction of discrimination against Arabs in France [...].

Socio-demographic information Participants provided information on age, gender, their nationality, and the nationality of their parents.

Experiment 4

[...] We conducted Experiment 4 to examine these alternative explanations. In Experiment 4, we included the heterogeneous and control conditions from Experiment 1, but we added two new conditions. In the “social norm condition,” we used a poster that was used by the French government in a public advertisement campaign 5 years prior to our experiment. The poster displays a single Arab individual and encourages viewers to stop discriminating against Arabs. In the“faces condition,”we used the same poster as in the heterogeneous condition, but we removed all information related to the heterogeneity of Arabs and replaced the slogan by a general appeal to stop discrimination. [...]

Participants Participants were enrolled in 24 classes at Clermont University, France. There were 486 undergraduate students (163 male and 323 female). Participants’ ages ranged from 17 to 33 years, with an average of M = 19.90 years (SD = 2.03 years). [...] Each classroom was randomly assigned to one of the four experimental conditions “control,”“social norm,”“faces,” and “heterogeneous.”

Procedure and stimulus material [...] During the first week, before the beginning of the class, one of the four posters was displayed on the classroom walls. The posters in the control condition and in the heterogeneous condition were identical to those used in Experiment 1. The posters used in the two other conditions are shown in Figure 3. As can be seen, the poster in the“social norms condition” contained the picture of a young Arab in casual clothing above a text with the following words: [Text Stimulus A]. The poster in the “faces condition” was identical to that in the heterogeneous condition, but the names of and the personal information about the individuals had been removed. Also, the slogan [Text Stimulus B]. After the class ended, the experimenter removed the poster. The following week, participants completed the questionnaire measuring their attitudes toward Arabs. [...]

Dependent measures Participants completed a variety of dependent measures all of which were described in detail in Experiments 1–3. We used a single item to measure participants’ perceived variability [...]. Prejudice was assessed with the Modern Racism Scale. For our measure of stereotypicality, participants indicated the extent to which they thought Arabs possessed five stereotypical positive [...] and five stereotypical negative traits [...]. As before, participants made their responses on continuous rating scales, and a score between 1 and 28 was later attributed to each response. Finally, in order to obtain a behavioral indicator of participants’ attitudes toward Arabs, we asked participants whether they would agree to volunteer some of their time for an Arab interest group in town and how much time they would be willing to devote to the planned meetings (discrimination).