Sequential Congruency Effects of Reverse Stroop Interference on Event-Related Potential Components for Go- and Nogo-Stimuli

Sequential congruency effects are observed in interference tasks, in which reaction times (RTs) are shorter for congruent stimuli preceded by congruent (cC) than incongruent stimuli (iC), and RTs are longer for incongruent stimuli preceded by congruent (cI) than incongruent stimuli (iI). These effects are interpreted as resulting from incongruent stimuli triggering attentional control in the next trial, which reduces cognitive control. This study aimed to examine sequential congruency effects on event-related potential (ERP) components for Go- and Nogo-stimuli. We used the hybrid reverse Stroop Go/Nogo task. The stimuli were Kanji characters, “赤” (i.e., red) and “青” (i.e., blue) painted in congruent and incongruent colors. Participants responded to one of the two characters (i.e, the Go-stimulus) and stopped responding to the other character (i.e., the Nogo-stimulus). The results indicated that the Nogo-N1 was reduced by trials preceded by incongruent stimuli compared with congruent ones, suggesting that color processing was inhibited by attentional control; however, there was no reduction in the Go-N1. In addition, the Nogo-N2 amplitudes were larger for cI than iI and iC than cC. On the other hand, the Go-N2 was not modulated by sequential modulation effects, which was lower for incongruent stimuli than congruent stimuli. These results indicate that the Nogo-N2 is involved in cognitive control, whereas the Go-N2 is associated with selection processing. These findings suggest that the modulation of sequential congruency effects of N1 and N2 required the response inhibition task demand; however, Go-P3 and Nogo-P3 amplitudes were the largest for cI. Therefore, the time range of ERP components might be related to the susceptibility of an interaction effect between response inhibition task demand and sequential congruency effects.

Sequential Congruency Effects of Reverse Stroop Interference On Event-Related Potential Components For Go- and Nogo-Stimuli

Sequential congruency effects are observed in interference tasks, in which RTs are shorter for congruent stimuli preceded by congruent (cC) than incongruent stimuli (iC), and RTs are longer for incongruent stimuli preceded by congruent (cI) than incongruent stimuli (iI). These effects are interpreted as resulting from incongruent stimuli triggering attentional control in the next trial, which reduces cognitive control. The aim of this study was to examine sequential congruency effects on ERP components for Go- and Nogo-stimuli using the hybrid reverse Stroop Go/Nogo task. Results indicated that the Nogo-N1 was reduced by trials preceded by incongruent stimuli compared to congruent ones, suggesting that color processing was inhibited by attentional control. However, there was no reduction in the Go-N1. Moreover, the Nogo-N2 amplitudes were larger for cI than iI and iC than cC. On the other hand, the Go-N2 was not modulated by sequential modulation effects, which was lower for incongruent stimuli than congruent stimuli. These results indicate that the Nogo-N2 is involved in cognitive control, whereas the Go-N2 is associated with selection processing. Therefore, it was suggested that response inhibition task demands are necessary for modulating the ERP components by sequential congruency effects.

The Backward Crosstalk Effect Does Not Depend on the Degree of a Preceding Response Conflict

A common observation in dual tasking is a performance decrement in one or both tasks compared with single tasking. Besides, more specific interference occurs depending on certain characteristics of the two tasks. In particular, even Task 1 performance is often improved when responses in both tasks are compatible (e.g., both require left responses) compared to when they are incompatible: the compatibility-based backward crosstalk effect (BCE). Similar to what is observed for conflict tasks, the BCE is sequentially modulated: It is larger following compatible than following incompatible trials. Previous work has attributed this observation to adaptation effects triggered by response conflict arising during incompatible trials. In two experiments, we assessed sequential modulations following trials with different degrees of such a response conflict. In contrast to our expectations, a clear and sizeable sequential modulation was observed even under conditions where no BCE, and thus no empirical sign of an objective response conflict, was present in the previous trial. Therefore, our results show sequential modulations even without prior response conflict, which is not the (sole) trigger of sequential modulations accordingly. We discuss these results with regard to other potential triggers such as the subjective experience of conflict or difficulty, episodic retrieval, and repetitions of response combinations.

Exploring an Emotional Basis of Cognitive Control in the Flanker Task

The emotional basis of cognitive control has been investigated in the flanker task with various procedures and materials across different studies. The present study examined the issue with the same flanker task but with different types of emotional stimuli and design. In seven experiments, the flanker effect and its sequential modulation according to the preceding trial type were assessed. Experiments 1 and 2 used affective pictures and emotional facial expressions as emotional stimuli, and positive and negative stimuli were intermixed. There was little evidence that emotional stimuli influenced cognitive control. Experiments 3 and 4 used the same affective pictures and facial expressions, but positive and negative stimuli were separated between different participant groups. Emotional stimuli reduced the flanker effect as well as its sequential modulation regardless of valence. Experiments 5 and 6 used affective pictures but manipulated arousal and valence of stimuli orthogonally The results did not replicate the reduced flanker effect or sequential modulation by valence, nor did they show consistent effects of arousal. Experiment 7 used a mood induction technique and showed that sequential modulation was positively correlated with valence rating (the higher the more positive) but was negatively correlated with arousal rating. These results are inconsistent with several previous findings and are difficult to reconcile within a single theoretical framework, confirming an elusive nature of the emotional basis of cognitive control in the flanker task.