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A brain-potential correlate of task-set conflict


  • This manuscript reports research carried out as part of Heike Elchlepp's PhD dissertation work under the supervision of the second author, and was supported by a studentship from the Economic and Social Research Council (UK). We thank Stephen Monsell and two anonymous reviewers for comments on the manuscript.

Address correspondence to: Heike Elchlepp, Psychology, College of Life and Environmental Sciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter EX4 4QG, UK. E-mail:


Brain-potential correlates of response conflict are well documented, but those of task conflict are not. Task-switching studies have suggested a plausible correlate of task conflict—a poststimulus posterior negativity—however, in such paradigms the negativity may also reflect poststimulus task-set reconfiguration postulated in some models. Here, participants alternated between single-task blocks of classifying letters and digits; hence, no within-block task-set reconfiguration was required. Presenting letters alongside digits slowed responses to the digits and elicited an ERP negativity from ∼350 ms, relative to task-neutral symbols presented alongside digits, consistent with task conflict. The negativity was also present for congruent digit-letter stimuli; this and the lack of behavioral response congruency effects indicate conflict at the level of task-set rather than response selection.