Neural cascade of conflict processing: Not just time-on-task

Cameron C. McKay, Berry van den Berg, Marty G. Woldorff*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    19 Citations (Scopus)
    94 Downloads (Pure)

    Abstract

    In visual conflict tasks (e.g., Stroop or flanker), response times (RTs) are generally longer on incongruent trials relative to congruent ones. Two event-related-potential (ERP) components classically associated with the processing of stimulus conflict are the fronto-central, incongruency-related negativity (N-inc) and the posterior late-positive complex (LPC), which are derived from the ERP difference waves for incongruent minus congruent trials. It has been questioned, however, whether these effects, or other neural measures of incongruency (e.g., fMRI responses in the anterior cingulate), reflect true conflict processing, or whether such effects derive mainly from differential time-on-task. To address this question, we leveraged high-temporal-resolution ERP measures of brain activity during two behavioral tasks. The first task, a modified Erikson flanker paradigm (with congruent and incongruent trials), was used to evoke the classic RT and ERP effects associated with conflict. The second was a non-conflict control task in which, participants visually discriminated a single stimulus (with easy and hard discrimination conditions). Behaviorally, the parameters were titrated to yield similar RT effects of conflict and difficulty (27 ms). Neurally, both within-task contrasts showed an initial fronto-central negative polarity wave (N2-latency effect), but they then diverged. In the difficulty difference wave, the initial negativity led directly into the posterior LPC, whereas in the incongruency contrast the initial negativity was followed a by a second fronto-central negative peak (N-inc), which was then followed by a considerably longer-latency LPC. These results provide clear evidence that the longer processing for incongruent stimulus inputs do not just reflect time-on-task or difficulty, but include a true conflict-processing component.

    Original languageEnglish
    Pages (from-to)184-191
    Number of pages8
    JournalNeuropsychologia
    Volume96
    DOIs
    Publication statusPublished - Feb-2017

    Keywords

    • Conflict processing
    • Task difficulty
    • Cognitive control
    • Time-on-task
    • EEG
    • ANTERIOR CINGULATE CORTEX
    • MEDIAL FRONTAL-CORTEX
    • COGNITIVE CONTROL PROCESSES
    • RESPONSE CONFLICT
    • STROOP TASK
    • ERROR LIKELIHOOD
    • FLANKER TASK
    • HUMAN BRAIN
    • DYNAMICS
    • INTERFERENCE

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