People should primarily use individuating information, when it is available, rather than stereotypes when judging others. Do they? This area of research has been highly controversial, with many researchers emphasizing the power of stereotypes to bias judgments (Devine, 1995; Fiske & Neuberg, 1990; Fiske & Taylor, 1991; Jones, 1986; Jost & Kruglanski, 2002) and others emphasizing the relatively modest influence of stereotypes and the relatively large role of individuating information (Jussim, Eccles, & Madon, 1996; Kunda & Thagard, 1996).
Fortunately, literally hundreds of studies have now been performed that address this issue, and, even more fortunately, multiple meta-analyses have been performed summarizing their results. Table 10.3 presents the results from meta-analyses of studies assessing stereotype bias in many contexts. It shows that the effects of stereotypes on person judgments, averaged over hundreds of experiments, range from 0 to .25. The simple arithmetic mean of the effect sizes is .10, which is an overestimate, because the meta-analyses with more studies yielded systematically lower effect sizes (r =–.43 between effect size and number of studies). The few naturalistic studies of the role of stereotypes in biasing person perception have yielded similarly small effects (e.g., Clarke & Campbell, 1955; Jussim et al., 1996; Madon et al., 1998).
How small is an effect of r = .10? It is small according to J. Cohen’s (1988) heuristic categorization of effect sizes. It is among the smallest effects found in social psychology (Richard et al., 2003). An overall effect of .10 means that expectancies substantially influence social perceptions about 5% of the time (as per Rosenthal’s [1991] binomial effect size display). This means that stereotypes do not influence perceptions 95% of the time.
In general, therefore, based on more than 300 experimental studies and a smaller number of naturalistic studies, stereotypes have only very modest influences on person perception. Of course, there is always the possibility that researchers have not searched in the right places or in the right way for powerful stereotype biases in person perception. At minimum, however, the burden of proof (for the existence of widespread, powerful stereotype biases in person perception) has shifted to those emphasizing such powerful biases.
The existence of small stereotype effects, however, does not necessarily mean that people do generally rely heavily on individuating information. However, the empirical evidence shows, in fact, that they do. The one meta-analysis that has addressed this issue found that the effect of individuating information on person perception was among the largest effects found in social psychology, r =.71 (Kunda & Thagard, 1996). In other words, people seem to be generally doing the right thing—relying on individuating information far more than stereotypes.