Event Related Potential Measures of Task Switching in the Implicit Association Test

Abstract

Since its creation in 1998, the Implicit Association Test (IAT) has become a commonly used measure in social psychology and related fields of research. Studies of the cognitive processes involved in the IAT are necessary to establish the validity of this measure and to suggest further refinements to its use and interpretation. The current thesis used ERPs to study cognitive processes associated with the IAT. The first experiment found significant differences in P300 amplitude in the Congruent and Incongruent conditions, which were interpreted as a reflection of greater equivocation in the Incongruent condition. The second experiment tested the task-set switching account of the IAT in much greater detail by analyzing each trial type separately. In the Congruent condition, all trial types elicited the same amplitude P300. Local probability, and the consequent checking and updating of working memory, was thought to be responsible for differences between trials of the Incongruent condition that required or did not require a task switch. The final experiment examined the role of working memory in the IAT by introducing obtrusive and irrelevant auditory stimuli. The results of Experiment 3 indicated that the introduction of an obtrusive and irrelevant auditory increment deviant has little overall effect on the IAT, and a similar effect on switch and no-switch trials within the Incongruent condition. This could have been because both the Congruent and Incongruent conditions of the IAT make such extensive demands on central processing resources that few are available to allow for the switching of attention, or it is possible that the IAT does not require significant updating of working memory. The usefulness of ERPs in the study of the IAT effect is demonstrated by the current research. In particular, the finding that behavioural results were not always consistent with the ERP results demonstrates that electrophysiological measures can complement traditional behavioural measures.