The dilution effect: Nondiagnostic information weakens the implications of diagnostic information

Abstract

In a series of studies, subjects were asked to make predictions about target individuals. Some subjects were given information about the target which pretest subjects had judged to be "diagnostic''-that is, had judged to be usefully predictive of the outcome. Other subjects were given a mix of information judged to be diagnostic and information judged to be "nondiagnostic" by pretest subjectsthat is, judged to be of little value for predicting the outcome. Subjects given mixed information made much less extreme predictions than did subjects given only diagnostic information. It was argued that this "dilution effect" occurs because people make predictions by making simple similarity judgments. That is, they compare the information they have about the target with their conception of outcome categories. The presence of individuating but nondiagnostic information about the target reduces the similarity between the target and those outcomes that are suggested by the diagnostic information. One of the major implications is that stereotypes and other "social knowledge structures" may be applied primarily to abstract, undifferentiated individuals and groups and may be largely set aside when judgments are made about concrete, individuated people.

Violating Conversational Conventions Disrupts Cognitive Processing of Attitude Questions

“…Our findings in this regard may have implications for reinterpreting other, previously documented effects of conversational norms violation (e.g., Dulany & Hilton, 1991). Consider, for example, the dilution effect (Nisbett et al, 1981). Tetlock et al (1996) showed that presenting nondiagnostic information causes underuse of diagnostic information partly because people assume that speakers are conforming to a norm dictating that all provided information should be relevant to the issue at hand.…”

“…Likewise, people presume that speakers provide information that they believe to be relevant to the conversation at hand. This was partly responsible for people's apparent underuse of diagnostic information when they were also given nondiagnostic information (Nisbett, Zukier, & Lemley, 1981;Tetlock, Lerner, & Boettger, 1996). In both of these cases and most others in this literature, researchers did not conform to a conversational norm when asking a question, but listeners presumed that they did, thus leading to misunderstandings (for other examples, see Dulany & Hilton, 1991;Schwarz, Strack, Hilton, & Naderer, 1991;Strack & Schwarz, 1992;Strack, Schwarz, & Wänke, 1991).…”

Performance monitoring in the Victorian health care system: an exploratory study

“…23 Nisbett, Zukier and Lemley termed this phenomenon the dilution effect. 24 The dilution effect may be the most serious consequence of the reported over-emphasis on financial and volume indicators.…”

And Yet They Move: The Impact of Direction of Deviance on Stereotype Change

“…This should result in reduced generalization. Analogously, it has been shown that the impact of stereotypes on the perception of individuals is reduced by neutral attributes (the dilution effect, see Nisbett, Zukier, & Lemley, 1981).…”