Neural time course of conflict adaptation effects on the Stroop task

• Published in: Neuropsychologia 2009-02, Vol.47 (3), p.663-670
• Main Authors: Larson, Michael J., Kaufman, David A.S., Perlstein, William M.
• Format: Article
• Language: English
• Subjects: ACC; Adaptation; Adolescent; Adult; Anterior cingulate; Behavioral psychophysiology; Biological and medical sciences; Brain - anatomy & histology; Brain - physiology; Brain Hemisphere Functions; Brain Mapping - methods; Cognition - physiology; Cognitive control; Cognitive Processes; Color; Color Perception - physiology; Conflict; Conflict (Psychology); Cues; Diagnostic Tests; Electroencephalography; Electrophysiology; ERP; Event-related potential; Evoked Potentials - physiology; Executive function; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Goal Orientation; Gratton effect; Humans; Male; Middle Aged; Neurons - physiology; Neuropsychological Tests; Photic Stimulation - methods; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time; Reaction Time - physiology; Reading Processes; Sequential trial; Stroop; Task Analysis; Young Adult
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2008.11.013

Cognitive control theory suggests conflict effects are reduced following high- relative to low-conflict trials. Such reactive adjustments in control, frequently termed “conflict adaptation effects,” indicate a dynamic interplay between regulative and evaluative components of cognitive control necessary for adaptable goal-directed behavior. The current study examined conflict adaptation effects while 36 neurologically-normal participants performed a single-trial color-naming Stroop task. Trials preceded by incongruent (high conflict) and congruent (low conflict) trials were compared for behavioral (response time [RT] and error rate) and electrophysiological (N450 and conflict SP components of the event-related potential [ERP]) concomitants of cognitive control. A conflict adaptation effect was present for RTs that could not be accounted for by associative or negative priming. ERPs revealed a parietal conflict slow potential (conflict SP) that differentiated incongruent from congruent trials and monotonically differentiated current trial congruency on the basis of previous-trial context (i.e., showed conflict adaptation); the fronto-medial N450 was sensitive to current trial congruency but not to previous-trial context. Direct comparison of normalized conflict SP and N450 amplitudes showed the conflict SP was sensitive to the effects of previous-trial context, while the N450 was so to a lesser extent and in a different pattern. Findings provide clarification on the neural time course of conflict adaptation and raise further questions regarding the relative roles of the parietal conflict SP and fronto-medial N450 in conflict detection and processing.