Chapter 9. The Less Than Awesome Power of Expectations to Bias Perception, Memory and Judgment<\/p>\n
Abstract<\/p>\n
The chapter critically evaluates the conclusions often reached on the basis of the early research testifying to the power of expectations to bias perception, memory, and judgment.\u00a0 It leads off by walking through several real world examples involving sports, academics, and the stock market, all of which strongly suggest that such biases are generally quite limited in daily life.\u00a0 It then revisits some of the early classic studies widely interpreted as demonstrating large and dramatic expectancy-confirming biases generally: 1) provided more evidence of accuracy or unbiased responding, than of bias; or 2) have never been replicated.\u00a0 After debunking the justifiability of testaments to the power of bias on the basis of these early classics, the chapter turns to meta-analyses of the wider literature \u2013 and shows that all meta-analyses assessing the effects of stereotypes or other expectancies on perception, judgment, and memory produce, on average, very small bias effects (averaging about r=.10).\u00a0 The inexorable conclusion is that the biasing effects of expectations on judgments is, in general, very small.<\/p>\n
EXCERPT:<\/i><\/b>
\n\u00a0\u00a0\u00a0 So, what have the meta-analyses [of the biasing effects of expectations] found?\u00a0 The second half of Table 6.1 has presented the results, but I review them here …\u00a0 The simple average of the effects obtained in these seven meta-analyses is .09.\u00a0 The weighted average (weighting the effect size by the number of studies included in each meta-analysis) is .07.
\nTranslated into lay English, this means that expectations bias judgments, on average, about 5-10% of the time (see footnote 4).\u00a0 Or, put another way, on average, expectancies fail to bias judgments about 90-95% of the time.\u00a0 I conclude, therefore, that neither the handful of high-impact studies often cited as demonstrating powerful biases, nor the broader, more general literature, demonstrate that expectancies typically have very powerful effects on perception and judgment.\u00a0 Such biases are undoubtedly real — they occurred in many studies reviewed here, and the meta-analyses consistently found evidence of bias.\u00a0 That being said, however, the only viable conclusion from this literature is that such biases are, in general, quite small.<\/i><\/p>\n","protected":false},"excerpt":{"rendered":"