The Stroop task is a central experimental paradigm used to probe cognitive control by measuring the ability of participants to selectively attend to task-relevant information and inhibit automatic taskirrelevant responses. Research has revealed variability in both experimental manipulations and individual differences. Here, we focus on a particular source of Stroop variability, the reverse-facilitation (RF; faster responses to nonword neutral stimuli than to congruent stimuli), which has recently been suggested as a signature of task conflict. We first review the literature that shows RF variability in the Stroop task, both with regard to experimental manipulations and to individual differences. We suggest that task conflict variability can be understood as resulting from the degree of proactive control that subjects recruit in advance of the Stroop stimulus. When the proactive control is high, task conflict does not arise (or is resolved very quickly), resulting in regular Stroop facilitation. When proactive control is low, task conflict emerges, leading to a slow-down in congruent and incongruent (but not in neutral) trials and thus to Stroop RF. To support this suggestion, we present a computational model of the Stroop task, which includes the resolution of task conflict and its modulation by proactive control. Results show that our model (a) accounts for the variability in Stroop-RF reported in the experimental literature, and (b) solves a challenge to previous Stroop models-their ability to account for reaction time distributional properties. Finally, we discuss theoretical implications to Stroop measures and control deficits observed in some psychopathologies.
Bibliographical noteFunding Information:
This research was supported by funding from the Rothschild foundation (Eyal Kalanthroff), the Molberger Scholar award (Eyal Kalan- throff), and by The Israel Science Foundation (Grant 79/15 to Eyal Kalanthroff; Grant 743/12 to Marius Usher). Funding sources had no other role other than financial support. We thank Daniel Algom, Yossi Tzelgov, and Desiree Meloul for critical reading and valuable input on this paper. An early version of the GRAIN Stroop model (without task-conflict) was explored by Marius Usher to account for Schizophrenia Stroop deficits, during postdoc in the lab of J. D Cohen, whose guidance is warmly acknowledged.
© 2017 American Psychological Association.
- Cognitive control
- Computational model
- Executive functions
- Reverse facilitation
- Stroop task