Abstract
BackgroundImplicit negative attitudes towards other races are important in certain kinds of prejudicial social behaviour. Emotional mechanisms are thought to be involved in mediating implicit “outgroup” bias but there is little evidence concerning the underlying neurobiology. The aim of the present study was to examine the role of noradrenergic mechanisms in the generation of implicit racial attitudes.MethodsHealthy volunteers (n = 36) of white ethnic origin, received a single oral dose of the β-adrenoceptor antagonist, propranolol (40 mg), in a randomised, double-blind, parallel group, placebo-controlled, design. Participants completed an explicit measure of prejudice and the racial implicit association test (IAT), 1–2 h after propranolol administration.ResultsRelative to placebo, propranolol significantly lowered heart rate and abolished implicit racial bias, without affecting the measure of explicit racial prejudice. Propranolol did not affect subjective mood.ConclusionsOur results indicate that β-adrenoceptors play a role in the expression of implicit racial attitudes suggesting that noradrenaline-related emotional mechanisms may mediate negative racial bias. Our findings may also have practical importance given that propranolol is a widely used drug. However, further studies will be needed to examine whether a similar effect can be demonstrated in the course of clinical treatment.Electronic supplementary materialThe online version of this article (doi:10.1007/s00213-012-2657-5) contains supplementary material, which is available to authorized users.
Highlights
Negative evaluations of minority groups are a central source of avoidance, discrimination, and conflict — problems which are of particular importance in today’s increasingly cosmopolitan world
Our results indicate that β-adrenoceptors play a role in the expression of implicit racial attitudes suggesting that noradrenaline-related emotional mechanisms may mediate negative racial bias
We found no effect of propranolol on the measure of explicit prejudice as judged using the Mann–Whitney U-test for independent, non-parametric data
Summary
Negative evaluations of minority groups are a central source of avoidance, discrimination, and conflict — problems which are of particular importance in today’s increasingly cosmopolitan world. The implicit association test (IAT) (Greenwald et al 2009) is a widely used method to assess implicit attitudes to which individuals may have limited introspective access (Nosek et al 2007). In this item-sorting task, latency differences between prejudice congruent and incongruent trials are evaluated, to measure implicit bias. A recent metaanalysis further suggests that the IAT is a consistently better predictor of discrimination against out-group members than measures of explicit prejudice (Poehlman et al 2004).
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