Physiological Evidence for the Time-dependent Resolution of Response Conflicts.

Cognitive control is related to goal-directed self-regulation abilities, which is fundamental for human development. Conflict control includes the neural processes of conflict monitoring and conflict resolution. Testosterone and cortisol are essential hormones for the development of cognitive functions. However, there are no studies that have investigated the correlation of these two hormones with conflict control in preadolescents. In this study, we aimed to explore whether testosterone, cortisol, and testosterone/cortisol ratio worked differently for preadolescent’s conflict control processes in varied conflict control tasks. Thirty-two 10-year-old children (16 boys and 16 girls) were enrolled. They were instructed to accomplish three conflict control tasks with different conflict dimensions, including the Flanker, Simon, and Stroop tasks, and electrophysiological signals were recorded. Salivary samples were collected from each child. The testosterone and cortisol levels were determined by enzyme-linked immunosorbent assay. The electrophysiological results showed that the incongruent trials induced greater N2/N450 and P3/SP responses than the congruent trials during neural processes of conflict monitoring and conflict resolution in the Flanker and Stroop tasks. The hormonal findings showed that (1) the testosterone/cortisol ratio was correlated with conflict control accuracy and conflict resolution in the Flanker task; (2) the testosterone level was associated with conflict control performance and neural processing of conflict resolution in the Stroop task; (3) the cortisol level was correlated with conflict control performance and neural processing of conflict monitoring in the Simon task. In conclusion, in 10-year-old children, the fewer processes a task needs, the more likely there is an association between the T/C ratios and the behavioral and brain response, and the dual-hormone effects on conflict resolution may be testosterone-driven in the Stroop and Flanker tasks.

Humans have to deal with conflicting information. This is studied in conflict tasks such as the Simon task or the flanker task. For example, participants respond with the left or right hand to the color of a stimulus (task-relevant stimulus feature) which is presented in a left or right position (irrelevant feature) in the Simon task or to a letter (relevant) which is flanked by same or different letters (irrelevant) in the flanker task. In incongruent trials, in which relevant and irrelevant stimulus features require different responses, reaction time is longer and errors are more frequent. This congruency effect is reduced after incongruent trials, dubbed congruency sequence effect (CSE). Here, we show that with temporally separated presentations of relevant and irrelevant stimulus features in the Simon task the CSE is strong with leading irrelevant feature, but declines with leading relevant feature. For the flanker task, this modulation of the CSE was unreliable. By means of an extended leaky, competing accumulator model, we contrasted two mechanisms of the CSE for the Simon task: gating of the irrelevant stimulus information and re-mapping of the stimulus positions to response positions after incongruent trials. The gating model failed to account for some aspects of the observed data which could be simulated by the re-mapping model. For the flanker task, there was not only a CSE, but also overall longer reaction times after incongruent trials. This required an extension of the re-mapping model in terms of higher response thresholds after incongruent than after congruent trials. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

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A central question in cognitive psychology concerns how humans selectively attend to task-relevant information while ignoring task-irrelevant information. This question is frequently studied using conflict tasks, such as the Simon, Eriksen flanker, and Stroop tasks that require responses to relevant stimulus features while ignoring irrelevant and potentially conflicting features. All conflict tasks produce better performance in congruent trials where task-relevant features and irrelevant features match compared with when they mismatch in incongruent trials: the congruency effect. However, they differ markedly in the temporal dynamics of this congruency effect and accordingly in their RT distributions. The Diffusion Model for Conflict tasks (DMC) was introduced as a model to formally account for all distributional patterns in conflict tasks. It integrates dual-route theories of cognitive control into the framework of sequential sampling models by positing two superimposed, independent evidence accumulation processes: a linear one for controlled processing of the task-relevant information, and a pulse-like one for automatic processing of the task-irrelevant information, in which activation first increases until a maximum and then decreases again. This review summarizes DMC's architecture, its core parameters, and its ability to account for various distributional patterns. We review and discuss applications of DMC across several psychological domains, and technical considerations such as parameter estimation and recovery. Limitations of the model are critically assessed, and fields of open research are outlined. Overall, DMC offers a general account of conflict processing. While a powerful tool for quantifying the dynamics of selective attention and cognitive control, there is still a limited standardization in its application, and more research is needed to extend DMC to other classes of conflict tasks.

Previous studies have shown that congruency effects are often reduced when exogenous cues predict conflict between targets and distractors in conflict tasks. However, it is unclear how such effects are modulated by implicit temporal cues, as prior findings have been mixed. To address this, we conducted two large-scale experiments (N = 270), supplementing mean performance analyses with diffusion modeling (Diffusion Model for Conflict tasks). In Experiment 1, short and long foreperiods (FPs) were associated with high or low conflict probabilities in classical two-choice versions of the Eriksen flanker and Simon tasks. Mean reaction time analyses revealed that conflict effects were generally reduced with conflict-predicting FPs in both tasks. However, for the Eriksen flanker task, this modulation was larger when the long rather than the short FP predicted conflict, whereas for the Simon task, this modulation was similar or, if any, larger for the short than the long conflict-predicting FP. Diffusion Model for Conflict task analyses, which accounted for task-specific temporal dynamics of congruency effects, suggested that reductions in conflict effects were driven mainly by stronger distractor suppression rather than enhanced target amplification. In Experiment 2, conflict effects were also reduced with conflict-predicting FPs in a confound-minimized four-choice version of the Eriksen flanker task, though effects were smaller and reached significance only in the Diffusion Model for Conflict task analyses. Overall, these findings suggest that temporal cueing of conflict can enhance cognitive control in conflict tasks by strengthening distractor suppression, albeit in a manner that is partly specific to the conflict task. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The congruency sequence effect (CSE) refers to the finding that the effect of cognitive conflict is smaller following conflicting, incongruent trials than after non-conflicting, congruent trials in conflict tasks, such as the Stroop, Simon, and flanker tasks. This is typically interpreted as an upregulation of cognitive control in response to conflict. Weissman, Jiang, & Egner (2014) investigated whether the CSE appears in these three tasks and a further variant where task-irrelevant distractors precede the target (prime-probe task), in the absence of learning and memory confounds in samples collected online. They found significant CSEs only in the prime-probe and Simon tasks, suggesting that the effect is more robust in tasks where the distractor can be translated into a response faster than the target. In this Registered Replication Report we collected data online from samples approx. 2.5 times larger than in the original study for each of the four tasks to investigate whether the task-related differences in the magnitude of the CSE are replicable (Nmin = 115, Nmax = 130). Our findings extend but do not contradict the original results: Bayesian analyses suggested that the CSE was present in all four tasks in RT but only in the Simon task in accuracy. The size of the effect did not differ between tasks, and the size of the congruency effect was not correlated with the size of the CSE across participants. These findings suggest it might be premature to conclude that the difference in the speed of distractor- vs target-related response activation is a determinant of the size of cross-trial modulations of control. The practical implications of our results for online data collection in cognitive control research are also discussed.

Previous studies have suggested that performance-contingent reward can modulate cognitive control by biasing irrelevant location-response associations in the Simon task. However, the influence of reward in the case of irrelevant words (Stroop task) or irrelevant flankers (Eriksen Flanker task) remains unclear. Across two preregistered experiments, the present study investigated the influence of reward on conflict processing with different types of distractors. Conflict effects on mean reaction time (RT) were reduced in the Simon task (Experiments 1 and 2) when incongruent versus congruent trials were rewarded, and this modulating effect of reward on conflict processing was also observed in the Eriksen flanker task (Experiment 2), but not in the Stroop task (Experiment 1). We propose that cognitive control adjustments to distractor-specific reward contingencies can be generalized across distractor types producing both perceptual-related (Flanker task) and motor-related (Simon task) conflict, but, if any, to a limited degree when distractors produce additional higher-level task conflict (Stroop task). In addition, distributional RT analyses (delta plots) revealed that rewarded distractor-response associations modulate cognitive control not only via biasing the strength (Simon and Eriksen tasks) but also the time-course of suppressing distractor processing (Eriksen task). Overall, the present study dissociated distractor-general and distractor-specific effects of reward on cognitive control.

In conflict tasks, such as the Simon, Eriksen flanker, or Stroop task, a relevant and an irrelevant feature indicate the same or different responses in congruent and incongruent trials, respectively. The congruency effect refers to faster and less error-prone responses in congruent relative to incongruent trials. Distributional analyses reveal that the congruency effect in the Simon task becomes smaller with increasing RTs, reflected by a negative-going delta function. In contrast, for other tasks, the delta function is typically positive-going, meaning that congruency effects become larger with increasing RTs. The Diffusion Model for Conflict tasks (DMC; Ulrich et al., Cognitive Psychology,78, 148–174, 2015) accounts for this by explicitly modeling the information accumulated from the relevant and the irrelevant features and attributes negatively- versus positively-sloped delta functions to different peak times of a pulse-like activation resulting from the task-irrelevant feature. Because the underlying function implies negative drift rates, Lee and Sewell (Psychonomic Bulletin & Review,31(5), 1–31, 2024) recently questioned this assumption and suggested their Revised Diffusion Model for Conflict tasks (RDMC). We address three issues regarding RDMC compared to DMC: (1) The pulse-like function is not as implausible as Lee and Sewell suggest. (2) RDMC itself comes with a questionable assumption that different parameters are required for congruent and incongruent trials. (3) Moreover, we present data from a new parameter recovery study, suggesting that RDMC lacks acceptable recovery of several parameters (in particular compared to DMC). In this light, we discuss RDMC as not (yet) a revised version of DMC.

The congruency sequence effect (CSE), or Gratton effect, describes diminished congruency effects (i.e., faster responses for <<<<< vs. <<><< stimuli in a flanker task) on trials following an incongruent trial compared to those following a congruent trial. Traditionally, the CSE is regarded as an index of conflict adaptation. Accounts of the CSE have typically emphasized either top-down (cognitive control) or bottom-up (associative) processes. To disentangle top-down and bottom-up contributions to the CSE, we compared performance on versions of Simon and flanker tasks that control for memory and learning effects present in the standard versions of these tasks with the standard tasks. We analyzed the data using a recently developed model that explains conflict effects in terms of attention-shifting dynamics, the revised diffusion model for conflict tasks. Our modeling analyses suggest the CSEs in both Simon tasks are mainly driven by across-trial changes in the way attention is loaded onto distractor information, consistent with top-down control. In contrast, for both flanker tasks, our model-based analysis does not provide clear evidence favoring either top-down or bottom-up contributions to the CSEs overall. Furthermore, we fit the standard version of these tasks while separately analyzing trials based on whether the response was repeated or alternated across successive trials. Model fits suggest a combination of both influences, with different patterns for congruent and incongruent trials. Performance benefits on congruent trials are driven by adjusting how attention is loaded onto distractor information based on the previous congruency types (i.e., top-down influence). However, on incongruent trials, asymmetrical repetition benefits are mainly due to faster memory retrieval (i.e., bottom-up influence) and reactive attentional control. Our findings highlight that a more nuanced and integrated theoretical framework is necessary to capture the interplay between top-down and bottom-up processes in explaining control mechanisms when analyzing different response sequences. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The role of task-relevant and task-irrelevant information in congruency sequence effects: Applying the diffusion model for conflict tasks

The recently developed diffusion model for conflict tasks (DMC) Ulrich et al. (Cognitive Psychology, 78, 148–174, 2015) provides a good account of data from all standard conflict tasks (e.g., Stroop, Simon, and flanker tasks) within a common evidence accumulation framework. A central feature of DMC’s processing dynamics is that there is an initial phase of rapid accumulation of distractor evidence that is then selectively withdrawn from the decision mechanism as processing continues. We argue that this assumption is potentially troubling because it could be viewed as implying qualitative changes in the representation of distractor information over the time course of processing. These changes suggest more than simple inhibition or suppression of distractor information, as they involve evidence produced by distractor processing “changing sign” over time. In this article, we (a) develop a revised DMC (RDMC) whose dynamics operate strictly within the limits of inhibition/suppression (i.e., evidence strength can change monotonically, but cannot change sign); (b) demonstrate that RDMC can predict the full range of delta plots observed in the literature (i.e., both positive-going and negative-going); and (c) show that the model provides excellent fits to Simon and flanker data used to benchmark the original DMC at both the individual and group level. Our model provides a novel account of processing differences across Simon and flanker tasks. Specifically, that they differ in how distractor information is processed on congruent trials, rather than incongruent trials: congruent trials in the Simon task show relatively slow attention shifting away from distractor information (i.e., location) while complete and rapid attention shifting occurs in the flanker task. Our new model highlights the importance of considering dynamic interactions between top-down goals and bottom-up stimulus effects in conflict processing.

Experimental manipulations in conflict tasks, e.g., the Stroop, Flanker, and Simon tasks, lead to systematically poorer performance in "incongruent" conditions that feature stimuli that contradict task goals. However, substantial recent debate surrounds whether individual differences in conflict task behavior reflect reliable, trait-like mechanistic processes. Much prior work uses difference scores, contrasting performance between incongruent and congruent trials to index conflict suppression ability, but recent work demonstrates these scores exhibit poor psychometric properties. Formal cognitive process models suggest that individual differences in conflict suppression are driven by task-general processes, as opposed to processes specialized for conflict. However, this prior work separately models cognitive process parameters and their covariation, which fails to adequately account for measurement error. Here, we model distinct mechanisms of conflict task performance and their covariance simultaneously using hierarchical Bayesian joint modeling methods for the first time which improves individual estimation and accounts for error. We fit the conflict linear ballistic accumulator model (LBA) to two large datasets containing multiple conflict tasks and test-retest sessions, and an additional large dataset containing a conflict task and simple perceptual decision-making task. First, within conflict tasks, we found moderate test-retest reliability for both conflict-specific processing mechanisms, and, to a larger degree, task-general mechanisms. Second, task-general, but not conflict-specific, mechanisms were correlated across different conflict tasks. Third, these task-general mechanisms were correlated between conflict tasks and a simple decision-making task without conflict suppression demands. Overall, we found robust individual differences in computational mechanisms underlying general decision-making, but not mechanisms specific to conflict processing.

Chronic cannabis use has been related to deficits in cognition (particularly memory) and the normal functioning of brain structures sensitive to cannabinoids. There is increasing evidence that conflict monitoring and resolution processes (i.e. the ability to detect and respond to change) may be affected. This study examined the ability to inhibit an automatic reading response in order to activate a more difficult naming response (i.e. conflict resolution) in a variant of the discrete trial Stroop colour-naming task. Event-related brain potentials to neutral, congruent and incongruent trials were compared between 21 cannabis users (mean 16.4 years of near daily use) in the unintoxicated state and 19 non-using controls. Cannabis users showed increased errors on colour-incongruent trials (e.g. "RED" printed in blue ink) but no performance differences from controls on colour congruent (e.g. "RED" printed in red ink) or neutral trials (e.g. "*****" printed in green ink). Poorer incongruent trial performance was predicted by an earlier age of onset of regular cannabis use. Users showed altered expression of a late sustained potential related to conflict resolution, evident by opposite patterns of activity between trial types at midline and central sites, and altered relationships between neurophysiological and behavioural outcome measures not evident in the control group. These findings indicate that chronic use of cannabis may impair the brain's ability to respond optimally in the presence of events that require conflict resolution and hold implications for the ability to refrain from substance misuse and/or maintain substance abstention behaviours.

Conflict control processing in adults with developmental dyslexia: An event related potentials study

Learning of irrelevant stimulus-response associations modulates cognitive control