The size of the Simon effect depends on the nature of the relevant task

Four experiments were conducted to investigate contextual modulations of the Simon effect. The results showed that the Simon effect was quantitatively different depending on which kind of task needed to be performed. Importantly, this effect did not depend on the relative processing time of the relevant dimension, nor on a direct or indirect overlap between the relevant and irrelevant stimulus part. To account for the data, we refer to the neural overlap hypothesis, which extends the definition of dimensional overlap (Kornblum, Hasbroucq, & Osman, 1990) with similarity of processing regions as the key factor for the interaction between relevant and irrelevant information processing.     

Post-conflict slowing: cognitive adaptation after conflict processing

The aftereffects of error and conflict (i.e., stimulus or response incongruency) have been extensively studied in the cognitive control literature. Each has been characterized by its own behavioral signature on the following trial. Conflict leads to a reduced congruency effect (Gratton effect), whereas an error leads to increased response time (post-error slowing). The reason for this dissociation has remained unclear. Here, we show that post-conflict slowing is not typically observed because it is masked by the processing of the irrelevant stimulus dimension. We demonstrate that post-conflict slowing does occur when tested in pure trials where helpful or detrimental impacts from irrelevant stimulus dimensions are removed (i.e., univalent stimuli).     

Top-down and bottom-up sequential modulations of congruency effects

Several studies have demonstrated reduced congruency effects after incongruent trials. The conflict monitoring hypothesis (Botvinick, Braver, Barch, Carter, & Cohen, 2001) assumes that this sequential modulation is based on top-down cognitive control and suggests that more control is engaged after the detection of conflict. An alternative account is based on repetition effects of stimulus and response features and can be considered bottom up. This study investigates both modulatory sources. In a Stroop task with two response-stimulus intervals (RSIs), we demonstrate that top-down modulation does not occur with a very short RSI, suggesting that it takes some time before the system can be reconfigured. Bottom-up modulation is observed for both RSIs. This finding demonstrates that two different sources simultaneously reduce congruency effects after incongruent trials.     

Stimulus conflict predicts conflict adaptation in a numerical flanker task

Conflict monitoring theory states that response conflict triggers conflict adaptation, resulting in reduced congruency effects after response-incongruent trials (Botvinick, Braver, Barch, Carter, & Cohen, 2001). Verbruggen, Notebaert, Liefooghe, and Vandierendonck (2006) observed conflict adaptation after stimulus-incongruent trials without any response conflict. In this study, we further explore the hypothesis that stimulus conflict is an important trigger for conflict adaptation. We propose a measure for stimulus conflict that adequately explains the data of Verbruggen et al. and new data from a numerical flanker task. We conclude that stimulus conflict and response conflict have dissociable effects on behavior Whereas response conflict is a good predictor of response times, stimulus conflict is a better predictor of the adaptation effect.     

Stimulus- and response-conflict-induced cognitive control in the flanker task

Recently, several studies have been conducted to investigate the top-down adjustments made after incongruent trials during conflict tasks. In the present study, we investigated conflict monitoring with different types of conflict. In a modified version of the flanker task, a distinction was made between stimulus—stimulus conflict and stimulus—response conflict. Six colors were mapped to three responses in order to exclude all sequences in which a relevant or an irrelevant stimulus- or response-related feature was repeated from trialn−1 to trialn. An analysis of the effect of the congruency of the previous trial demonstrated that conflict adaptation was present. The stimulus congruency effect was reduced after both a stimulus-incongruent trial and a response-incongruent trial. The response congruency effect did not vary as a function of previous congruency. These findings are discussed in relation to the distinction between conflict detection and conflict regulation.     

Testing the dopamine overdose hypothesis in action control: A study in people with Parkinson's disease

Prior work on patients with Parkinson's disease (PD) has shown that the administration of dopaminergic medication in the early to intermediate stages of PD benefits (motor) functions associated with the dopamine-depleted dorsal striatal circuitry but may ‘overdose’ and interfere with (cognitive) functions associated with the relatively intact ventral striatal circuitry. The present study aimed to elucidate this so-called dopamine overdose hypothesis for the action control domain. Using a within-subject design in a sample of 13 people with PD, we evaluated the effect of dopaminergic medication on two cognitive processes underlying goal-directed behaviour, namely action selection and initiation through event binding and conflict adaptation. We also investigated whether individual differences in the magnitude of medication effects were associated across these processes. Results showed no indications that dopaminergic medication affects action selection and initiation or conflict adaptation in PD patients. Additionally, we observed no correlations between both cognitive processes nor between individual differences in medication effects. Our findings do not support the notion that dopaminergic medication modulates action control processes, suggesting that the dopamine overdose hypothesis may only apply to a specific set of cognitive processes and should potentially be refined.     

Dissociating conflict adaptation from feature integration: a multiple regression approach

Congruency effects are typically smaller after incongruent than after congruent trials. One explanation is in terms of higher levels of cognitive control after detection of conflict (conflict adaptation; e.g., M. M. Botvinick, T. S. Braver, D. M. Barch, C. S. Carter, & J. D. Cohen, 2001). An alternative explanation for these results is based on feature repetition and/or integration effects (e.g., B. Hommel, R. W. Proctor, & K.-P. Vu, 2004; U. Mayr, E. Awh, & P. Laurey, 2003). Previous attempts to dissociate feature integration from conflict adaptation focused on a particular subset of the data in which feature transitions were held constant (J. G. Kerns et al., 2004) or in which congruency transitions were held constant (C. Akcay & E. Hazeltine, in press), but this has a number of disadvantages. In this article, the authors present a multiple regression solution for this problem and discuss its possibilities and pitfalls.     

New visuospatial associations by training verbospatial mappings in the first language

We investigated whether verbospatial and visuospatial information share a common representation. We demonstrate that when the associations from spatial words to spatial responses are altered, so that the word left becomes associated with a right response and the word right with a left response, the associations from the spatial locations left and right to the spatial responses also change. This effect was only observed for first-language spatial words (Dutch) and not for second-language spatial words (French), and it did not increase when these languages were combined. The findings argue for shared spatial representations for different types of spatial input.     

Going,going, gone? Proactive control prevents the congruency sequence effect from rapid decay

The congruency sequence effect, the finding of a reduced congruency effect following incongruent trials in conflict tasks, has received considerable attention in the research on cognitive control over the last two decades. This effect can reflect either the expectancy-guided, preparatory biasing of attention in anticipation of the upcoming stimulus (i.e. proactive control), or the phasic enhancement of the attentional set in response to conflict on the previous trial (i.e. reactive control). A recent study by Egner et al. in Front Psychol 1 (2010) set out to contrast these two alternatives, by exploring the congruency sequence effect across a wide range of inter-trial intervals. It was found that congruency sequence effects were subject to rapid decay over time. This decay fits well with the notion of reactive control, while at the same time speaking against the involvement of proactive regulation—which should also (and even mainly) be evident at longer intervals. In the present study, we first replicate the reduction of the congruency sequence effect with increasing inter-trial interval in a face-word Stroop task. In a second experiment, we show that congruency sequence effects are observed at longer intervals, too, when the proportion of trials with the longest inter-trial interval is increased. Our findings indicate that proactive control can prevent the congruency sequence effect from decaying rapidly.     

Gratitude and personal functioning among earthquake survivors in Indonesia

This study examined the potential role of gratitude as a protective factor against posttraumatic stress (PTS) symptomatology and global distress (GD) in the wake of disasters. Using longitudinal methodology, we assessed positive coping, gratitude, PTS symptomatology, and GD among 310 survivors of the 2009 Padang earthquake in Indonesia five and eight months after the disaster. Psychological hardiness and neuroticism were also measured at baseline. A general prototype model was constructed to predict scores on each of the dependent variables (GD and PTS symptomatology) at both time points. Hardiness and neuroticism were associated with GD and PTS at Time 1, but gratitude and positive coping had concurrent associations with these variables at Time 2. The unique association between gratitude and impairment at Time 2 suggests that it may play a role in adjustment to extreme disaster, but that it takes time to do so.