Neural Correlates of the Stroop Effect: an EEG Brainwave Analysis of Prefrontal Cognitive Load During Incongruent Colour-Word Processing

Shaw, Neil · 2026 · Crossref

DOI: 10.58806/irijsh.2026.v3i6n06

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Summary

This study investigates the neural oscillatory dynamics associated with the Stroop colour-word interference effect, specifically focusing on prefrontal cognitive load during incongruent processing. While the Stroop paradigm is a well-established test of executive function, prior research has largely focused on reaction times and event-related potentials, leaving the concurrent effects on relative power across all canonical EEG frequency bands undercharacterized. The authors aimed to address this gap by analyzing brainwave changes in gamma, beta, alpha, theta, and delta bands to provide a comprehensive view of the neural mechanisms underlying conflict resolution and inhibitory control. The experimental design involved eight healthy adult participants (four male, four female) who performed two tasks: a congruent control condition (naming ink color matching the word) and an incongruent Stroop condition (naming ink color conflicting with the word). EEG data were collected using a consumer-grade Brain Link EEG Headband connected to the Basic Detection application, which recorded relative percentage power for the five frequency bands from the prefrontal cortex. Task-completion times were manually recorded. The study employed a within-subjects design, comparing neural and behavioral metrics between the two conditions under identical environmental settings. The results revealed distinct and consistent shifts in EEG band power and behavioral performance. The Stroop condition caused a near-doubling of mean task-completion time, increasing from 11.9 seconds in the control condition to 27.0 seconds. Neurologically, this behavioral slowing was accompanied by a significant surge in delta power, which increased by 16.3 percentage points (from 34.5% to 50.8%), becoming the dominant oscillatory component. Conversely, beta power decreased markedly by 9.2 percentage points (from 22.3% to 13.1%), while gamma, alpha, and theta powers showed modest reductions. These changes were observed across all participants, despite substantial individual variability in baseline oscillatory profiles. The authors interpret these findings as evidence of heightened prefrontal cortex engagement required to override automated reading responses. The surge in delta power is attributed to effortful inhibitory processing and the reconstruction of non-default cognitive frames, while the reduction in beta power reflects the disruption of working memory maintenance circuits during rule reconfiguration. The study concludes that the Stroop effect fundamentally taxes the prefrontal capacity to assert deliberate overrides of automatic processing, a mechanism measurable through specific EEG oscillatory signatures. These findings have translational implications for clinical neuropsychology, neuroergonomics, and the design of brain-computer interfaces, offering a robust method for monitoring cognitive load and executive function.

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• neuro workload indices