They found that ratings of others did not predict group ratings and better than ratings of the self did. In addition, the group ratings were more accurate the more they projected; basically, typical group members made more accurate group ratings because they projected. The visual salience of the roommate ended up decreasing projection tendencies.

Study 2 Results: Self & Other Knowledge

A follow up study that investigated if the visual salience (presence) of another would change (specifically increase) how much one's knowledge of someone else would contribute to ratings of a group. Methods were the similar to the first study except they used only a subset of terms and the other individual was physically present.

Alma College

Investigated if knowledge of individual group members could predict our judgements about characteristics that belong to that entire group. Also compared the differences in the prediction of the group characteristics among self knowledge and group member knowledge.

Self and Other Knowledge and Group Characteristic Judgements

Krueger, J., & Stanke, D. (2001). The role of self-referent and other-referent knowledge in perceptions of group characteristics. Personality and Social Psychology Bulletin, 27(7), 878-888.

Self and Other-Referent Knowledge in Perceptions
of Group Characteristics

Investigated the idea that since self-referent information is more accessible, has more connections, and is more deeply encoded that it should be more influential in the group estimates than other-referent information. 
Participants were given a random number to remember during the task. Used 24 trait adjectives and participants had to indicate if the term was indicative of themselves, a roommate, and a university student.  At the end they had to recall the number and indicate how similar and how much they liked each person.

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