Strategy and Processing Speed Eclipse Individual Differences in Control Ability in Conflict Tasks

Craig Hedge*, Georgina Powell, Aline Bompas, Petroc Sumner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Response control or inhibition is one of the cornerstones of modern cognitive psychology, featuring prominently in theories of executive functioning and impulsive behavior. However, repeated failures to observe correlations between commonly applied tasks have led some theorists to question whether common response conflict processes even exist. A challenge to answering this question is that behavior is multifaceted, with both conflict and nonconflict processes (e.g., strategy, processing speed) contributing to individual differences. Here, we use a cognitive model to dissociate these processes; the diffusion model for conflict tasks (Ulrich et al., 2015). In a meta-analysis of fits to seven empirical datasets containing combinations of the flanker, Simon, color-word Stroop, and spatial Stroop tasks, we observed weak ( r < .05) zero-order correlations between tasks in parameters reflecting conflict processing, seemingly challenging a general control construct. However, our meta-analysis showed consistent positive correlations in parameters representing processing speed and strategy. We then use model simulations to evaluate whether correlations in behavioral costs are diagnostic of the presence or absence of common mechanisms of conflict processing. We use the model to impose known correlations for conflict mechanisms across tasks, and we compare the simulated behavior to simulations when there is no conflict correlation across tasks. We find that correlations in strategy and processing speed can produce behavioral correlations equal to, or larger than, those produced by correlated conflict mechanisms. We conclude that correlations between conflict tasks are only weakly informative about common conflict mechanisms if researchers do not control for strategy and processing speed.
Original languageEnglish
JournalJournal of Experimental Psychology: Learning, Memory, and Cognition
Early online date30 Sept 2021
Publication statusE-pub ahead of print - 30 Sept 2021

Bibliographical note

This article has been published under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Copyright for this article is retained by the author(s). Author(s) grant(s) the American Psychological Association the exclusive right to publish the article and identify itself as the original publisher.

Funding: This work was supported by the Economic and Social Research Council(ES/K002325/1) and by the Wellcome Trust (104943/Z/14/Z).


  • reaction time
  • inhibition (psychology)
  • cognitive modelling
  • Response control
  • individual differences
  • impulsivity


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