Contents

CHAPTER 8: Complex Designs 269of prejudice, in which “members of stigmatized groups develop belief systemsabout being devalued and that these expectations cause them to become especiallyalert or vigilant for signs of devaluation” (Kaiser et al., 2006, p. 332).In addition, Kaiser et al. noted that theories of attentional processes statethat attention is a limited resource. People who experience prejudice mayallocate attention toward cues that threaten their social identity and thereforehave less attentional resources available for other tasks. For example,students in a classroom setting who perceive possible prejudice may allocatetheir attention, both consciously and nonconsciously, to potential threats totheir social identity, and this diverted attention could impair their classroomperformance. Importantly, however, because Kaiser et al. manipulated the independentvariable of social-identity threat with two levels, threat and safety,they were able to demonstrate that attentional resources are not diverted topotential threats when individuals believe they are safe from social-identitythreats. This finding reinforces the importance of creating environments thatare as free of prejudice as possible.Psychological theories involving topics such as social identity and prejudiceare often complex. In order to explain prejudice, for example, psychologistsneed to describe behavioral, cognitive, and emotional processes at individual,group, and societal levels. As you might imagine, experimental tests of complextheories can lead to contradictory findings. For example, consider a hypotheticalexample in which a study of prejudice shows that members of a devaluedgroup do not experience heightened nonconcious attention to social-identitythreats. How would this seemingly contradictory finding be incorporated intoa theory of prejudice which states that stigmatized individuals attend to potentialthreats to their identity? As data from the Kaiser et al. experiment suggest,one interpretation of this finding might involve the independent variable ofsocial-identity condition, threat or safety. The contradictory finding could beinterpreted by suggesting that participants in the hypothetical study of prejudicefelt safe from social-identity threats and therefore did not allocate attentionto potential sources of devaluation.A common approach to resolving contradictory findings is to include in theresearch design independent variables that address potential sources of contradictoryfindings (for example, by including threat and safety conditions inthe design). More generally, complex designs can be extremely useful in trackingdown the reasons for seemingly contradictory findings when theories aretested. The process can be a painstaking one, but it can also be very worthwhile.Interaction Effects and External Validity• When no interaction effect occurs in a complex design, the effects ofeach independent variable can be generalized across the levels of theother independent variable; thus, external validity of the independentvariables increases.• The presence of an interaction effect identifies boundaries for the externalvalidity of a finding by specifying the conditions in which an effect of anindependent variable occurs.