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.

Participants Participants for the current investigation included 158 students recruited from introductory and developmental psychology courses at a Midwestern university. The sample was 63 % female, 85 % Caucasian, with a mean age of 19.9-years (SD = 3.8) old and a mean self-reported BMI of 25.0 (SD = 5.1). Forty-six percent (N = 73) were freshman, 24 % (N = 38) were sophomores, 19 % (N = 30) were juniors, and 11 % (N = 17) were seniors. [...]

Study design [...] Participants were randomly assigned to one of four conditions [...]: (1) control group, (2) a trait prevalence feedback condition, (3) an anonymous feedback condition, and (4) a public feedback group. [...] Participants in the anonymous feedback, trait prevalence, and control group conditions were administered first-time measures in a large, classroom setting. [...] It was explained that because a computer arbitrarily generated these measures, they might have to complete the same questionnaire more than once. [...] These instructions would be most informative for the control group condition because they would be asked to complete the exact measures a second time without receiving anonymous or trait prevalence feedback. In the first session, participants completed the Obese Persons Trait Survey (OPTS) followed by the Antifat Attitudes Questionnaire (AFAQ). [...] One week later, participants in the anonymous feedback, trait prevalence feedback, and control group returned for a second session, again in a classroom setting. Participants in the control group were given a generic statement about the purpose of the study and were not given feedback. Participants in the anonymous and trait prevalence feedback conditions were given the measures from the previous week modified to include either peer or trait prevalence feedback, respectively. In the anonymous feedback condition, participants were given written feedback purportedly documenting ‘‘the average percentage ratings of other students who believed that obese people possessed each of the different positive and negative traits’’. In the trait prevalence condition, participants were given written feedback purportedly documenting ‘‘the actual prevalence of these characteristics among obese individuals, as determined by scientific research’’. [...] In the public feedback condition, during the first assessment, to diminish the influence of public administration of the questionnaires at phase 2, participants were asked to report answers to the OPTS publically with a member of the research team individually. During the second assessment 1 week later, public feedback participants attended what appeared to be a group session with three other undergraduates who were also, allegedly participating in the study. However, the three other undergraduates were confederates, trained to respond in a rehearsed manner for the purpose of the current investigation. The experimenter asked the participant and confederates to complete the OPTS in a fashion such that they took turns reading their answers out loud to each item. [...] Seating during the experiment was arranged such that the participant answered each question last. Consistent with the trait prevalence and anonymous feedback conditions, confederates responded in a predetermined manner such that their responses averaged 20 points above each participant’s percentage ratings of positive traits and 20 points below each participant’s percentage estimates of negative traits on the OPTS that was completed the prior week. [...]

Measures

Obese Persons Trait Survey The Obese Person Trait Survey consists of 20 items listing stereotypical traits, including 10 negative [...] and 10 positive [...] characteristics. Participants estimated the percentage (between 0 and 100 percent) of obese persons who possess these traits. [...]

Anti-fat Attitudes Questionnaire This measure is a 13-item scale including three subscales: Dislike of Fat People [...], Fear of Fat [...], and Beliefs about the Controllability of Weight [...]. Participants rate each item on a scale from 1 to 9, with higher numbers indicating greater dislike, fear, or belief in the controllability of weight. [...]