Motor conflict in Stroop tasks : direct evidence from single-trial electro-myography and electro-encephalography

Szucs, Denes, Soltesz, Fruzsina, & White, Sonia (2009) Motor conflict in Stroop tasks : direct evidence from single-trial electro-myography and electro-encephalography. NeuroImage, 47(4), pp. 1960-1973.

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Several brain imaging studies have assumed that response conflict is present in Stroop tasks. However, this has not been demonstrated directly. We examined the time-course of stimulus and response conflict resolution in a numerical Stroop task by combining single-trial electro-myography (EMG) and event-related brain potentials (ERP). EMG enabled the direct tracking of response conflict and the peak latency of the P300 ERP wave was used to index stimulus conflict. In correctly responded trials of the incongruent condition EMG detected robust incorrect response hand activation which appeared consistently in single trials. In 50–80% of the trials correct and incorrect response hand activation coincided temporally, while in 20–50% of the trials incorrect hand activation preceded correct hand activation. EMG data provides robust direct evidence for response conflict. However, congruency effects also appeared in the peak latency of the P300 wave which suggests that stimulus conflict also played a role in the Stroop paradigm. Findings are explained by the continuous flow model of information processing: Partially processed task-irrelevant stimulus information can result in stimulus conflict and can prepare incorrect response activity. A robust congruency effect appeared in the amplitude of incongruent vs. congruent ERPs between 330–400 ms, this effect may be related to the activity of the anterior cingulate cortex.

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ID Code: 32343
Item Type: Journal Article
Refereed: Yes
Keywords: Response competition, Anterior cingulate cortex, Conflict resolution, Numerical Stroop paradigm, Continuous flow model, ERP, EMG
DOI: 10.1016/j.neuroimage.2009.05.048
ISSN: 1053-8119
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > NEUROSCIENCES (110900)
Australian and New Zealand Standard Research Classification > PSYCHOLOGY AND COGNITIVE SCIENCES (170000) > COGNITIVE SCIENCE (170200)
Divisions: Current > QUT Faculties and Divisions > Faculty of Education
Current > Schools > School of Early Childhood & Inclusive Education
Deposited On: 19 Aug 2010 23:01
Last Modified: 29 Feb 2012 14:23

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