An fMRI Study of Response and Semantic Conflict in the Stroop Task.

Michael G Wadsley,Benjamin A Parris,Maria Augustinova,Ludovic Ferrand,Abdelmalek Benattayallah,Nabil Hasshim

doi:10.3389/fpsyg.2019.02426

Abstract

An enduring question in selective attention research is whether we can successfully ignore an irrelevant stimulus and at what point in the stream of processing we are able to select the appropriate source of information. Using methods informed by recent research on the varieties of conflict in the Stroop task the present study provides evidence for specialized functions of regions of the frontoparietal network in processing response and semantic conflict during Stroop task performance. Specifically, we used trial types and orthogonal contrasts thought to better independently measure response and semantic conflict and we presented the trial types in pure blocks to maximize response conflict and therefore better distinguish between the conflict types. Our data indicate that the left inferior PFC plays an important role in the processing of both response and semantic (or stimulus) conflict, whilst regions of the left parietal cortex (BA40) play an accompanying role in response, but not semantic, conflict processing. Moreover, our study reports a role for the right mediodorsal thalamus in processing semantic, but not response, conflict. In none of our comparisons did we observe activity in the anterior cingulate cortex (ACC), a finding we ascribe to the use of blocked trial type presentation and one that has implications for theories of ACC function.

Highlights

The Stroop task (Stroop, 1935; MacLeod, 1991) has been referred to as the “gold standard” measure of selective attention (MacLeod, 1992)
We presented the trial types in pure blocks to both maximize response conflict and assess the role of the ACC in Stroop task performance
In what follows we summarize our findings by considering their implications for each of the regions associated with Stroop task performance

Summary

Introduction

The Stroop task (Stroop, 1935; MacLeod, 1991) has been referred to as the “gold standard” measure of selective attention (MacLeod, 1992) It elicits cognitive conflict by presenting two sources of information one of which is the relevant to-be-identified color and the other an irrelevant word and must be ignored. The Stroop interference effect refers to the finding that naming aloud the color that a word is printed in takes longer when the word denotes a different color (e.g., the word red displayed in blue font; an incongruent trial) compared to a baseline control condition (e.g., top in red or xxxx in red). The Stroop facilitation effect refers to the finding that naming aloud the color that a word is printed in is faster when the word denotes the same color (e.g., the word red displayed in red font; an congruent trial) compared to a baseline control condition. The present paper addressed just this issue by investigating the neural substrates of multiple sources of competition in the Stroop task

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Conclusion