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In the Simon task, participants perform a decision on non-spatial features (e.g., stimulus color) by responding with a left or right key-press to a stimulus presented on the left or right side of the screen. In the flanker task, they classify the central character while ignoring the flanking characters. In each task, there is a conflict between the response-relevant features and the response-irrelevant features (i.e., the location on the screen for the Simon task, and the flankers for the flanker task). Thus, in both tasks, resolving conflict requires to inhibit irrelevant features and to focus on relevant features. When both tasks were combined within the same trial (e.g., when the row of characters was presented on the left or right side of the screen), most previous research has shown an interaction. In the present study, we investigated whether this interaction is affected by a multiplicative priming of the correct response occurring when both Simon and flanker irrelevant features co-activate the correct response (Exp. 1), a spatial overlap between Simon and flanker features (Exp. 2), and the learning of stimulus-response pairings (Exp. 3). The results only show an impact of multiplicative priming.

The purpose of the present study was to determine whether responding to multiple concurrent conflicts results in a simultaneous or sequential conflict resolution. To this end, we measured event-related potentials (ERPs) in a paradigm combining a Stroop and a flanker task. In this paradigm, participants were asked to respond to the color of the central letter while ignoring the meaning of the word (Stroop task) and the color of the flanking letters (flanker task). Trials were either incongruent (i.e., inducing a conflict between two response alternatives) or congruent (i.e., inducing no response conflict) in both tasks, or incongruent in one task and congruent in the other task. The behavioral results showed a smaller Stroop congruency effect (i.e., a smaller difference between Stroop incongruent and congruent trials) for flanker incongruent than for flanker congruent trials, replicating previous findings. The ERP results showed that an early ERP component (i.e., P2) was associated with the resolution of the flanker conflict, whereas a later component (i.e., N450) was associated with the resolution of the Stroop conflict. Together, these findings emphasize a sequential organization of conflict resolution processes in the brain which is adaptive when facing multiple concurrent conflicts.

It is assumed that we recruit cognitive control (i.e., attentional adjustment and/or inhibition) to resolve 2 conflicts at a time, such as driving toward a red traffic light and taking care of a near-by ambulance car. A few studies have addressed this issue by combining a Simon task (that required responding with left or right key-press to a stimulus presented on the left or right side of the screen) with either a Stroop task (that required identifying the color of color words) or a Flanker task (that required identifying the target character among flankers). In most studies, the results revealed no interaction between the conflict tasks. However, these studies include a small stimulus set, and participants might have learned the stimulus-response mappings for each stimulus. Thus, it is possible that participants have more relied on episodic memory than on cognitive control to perform the task. In 5 experiments, we combined the 3 tasks pairwise, and we increased the stimulus set size to circumvent episodic memory contributions. The results revealed an interaction between the conflict tasks: Irrespective of task combination, the congruency effect of 1 task was smaller when the stimulus was incongruent for the other task. This suggests that when 2 conflicts are presented concurrently, the control processes induced by 1 conflict source can affect the control processes induced by the other conflict source. (PsycINFO Database Record

Working memory (WM) holds and manipulates representations for ongoing cognition. Oberauer (Psychology of Learning and Motivation, 51, 45–100, 2009) distinguishes between two analogous WM sub-systems: a declarative WM which handles the objects of thought, and a procedural WM which handles the representations of (cognitive) actions. Here, we assessed whether analogous effects are observed when participants switch between memory sets (declarative representations) and when they switch between task sets (procedural representations). One mechanism assumed to facilitate switching in procedural WM is the inhibition of previously used, but currently irrelevant task sets, as indexed by n-2 task-repetition costs (Mayr & Keele, Journal of Experimental Psychology: General, 129(1), 4–26, 2000). In this study we tested for an analogous effect in declarative WM. We assessed the evidence for n-2 list-repetition costs across eight experiments in which participants switched between memory lists to perform speeded classifications, mental arithmetic, or a local recognition test. N-2 list-repetition costs were obtained consistently in conditions assumed to increase interference between memory lists, and when lists formed chunks in long-term memory. Further analyses across experiments revealed a substantial contribution of episodic memory to n-2 list-repetition costs, thereby questioning the interpretation of n-2 repetition costs as reflecting inhibition. We reanalyzed the data of eight task-switching experiments, and observed that episodic memory also contributes to n-2 task-repetition costs. Taken together, these results show analogous processing principles in declarative and procedural WM, and question the relevance of inhibitory processes for efficient switching between mental sets.

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2018; Aachen 1 Online-Ressource (XII, 168 Seiten) : Illustrationen (2018). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2018, To deal with the flood of information that we are confronted with in daily life, the cognitive system allows to quickly switch between the processing of different tasks. In the present thesis, I examine complex task switching situations in which different components of the task representation switch independently and randomly between trials. In such paradigms, typically, a robust interaction of the components' switches and repetitions is obtained that indicates their integrated processing. It was the aim of the present thesis to identify the general mechanism underlying the component interactions. I start with a review of findings and theories reported in previous studies, and I identify three different interaction pattern types, which are defined by their interactions’ strengths. In the four studies, which are part of this thesis, the component interaction was examined in setups with auditory stimuli. Namely, an auditory attention component and a judgment component led to a rather weakly pronounced interaction pattern. Additional manipulations showed that this interaction pattern was not modulated by modality-specific processing demands and that it even arose when the attention switches were elicited automatically by exogenous cues. Moreover, the component that was cued in the beginning of the trial seemed to dominate the interaction pattern. When there was sufficient time for cue-based preparation of an attention switch, the interaction pattern became more pronounced. Similarly more pronounced patterns were found with instructed dependencies between the components. They allowed a preparation of a component based on the processing of the other component. Dependencies were especially evident in the interaction of a judgment component and a response component. The latter component interaction has elicited a rather separate line of research in the past years (i.e., studies on response repetition effect). As an explanation for the interaction pattern, inhibition of the just executed response was proposed. Yet, the similarities between the interaction of judgment component and response component, and the interactions of other components rather point towards a general mechanism of integrated component processing. A component interaction seems to be generally elicited to a large part by episodic priming and temporal episodic binding of the components. In component switches, in contrast, active preparation during a sufficiently long interval and facilitated switches due to instructed component dependencies seems to affect performance, too. Altogether, the present thesis points towards a general mechanism of integrated component processing and emphasizes that future research on multicomponent switching and on response repetition effects may benefit from more exchange., Published by Aachen

Inhibition of abandoned tasks in task switching can be inferred when a worse performance is found with n - 2 task repetitions (ABA sequences) than with nonrepetitions (CBA sequences). Recent evidence has shown that this inhibition effect decreases with long intertrial intervals (i.e., response-cue intervals, RCIs). Two alternatives have been proposed to account for this decrease. One alternative attributes the observed decrease to the decay of inhibition itself. The other alternative proposes that decay of the activation of competing tasks reduces the interference and leads to less inhibition. To decide between these alternatives, we manipulated RCI trialwise. The results favor the decay-of-activation account as an explanation for the decreased inhibition effect. This links the amount of inhibition to the activation level of the competing tasks, whereas evidence for the decay of inhibition remains weak.

The present study investigates the influence of preparation on inhibitory effects in cued task switching. In three experiments, we assessed n − 2 repetition costs as marker of inhibition of the just executed and now irrelevant task by comparing performance in task sequences such as ABA (i.e., n − 2 repetitions, with A, B and C standing for different tasks) to task sequences such as CBA (i.e., n − 2 switches). Specifically, we varied the cue–target interval (CTI) to examine cue-based preparation effects. In addition, we manipulated cue type (i.e., abstract, verbal, and direct cues) across the three experiments. We obtained significant reductions of n − 2 repetition costs with prolonged CTI when using abstract cues (i.e., coloured frames) and task names (i.e., digit), but not when using the task-specific stimulus–response mapping as cue for the upcoming task. These data suggest that cue-based preparation is not a uniform process but depends on the information provided by the cue.

The human cognitive system is equipped with various processes for dealing with everyday challenges. One of such processes is the inhibition of currently irrelevant goals or mental task-sets, which can be seen as a response to the critical event of information overflow in the cognitive system and challenging the cognitive system’s ability to keep track of ongoing demands. In two experiments, we investigate the flexibility of the inhibitory process by inserting rare non-critical events (25% of all trials), operationalized as univalent stimuli (i.e., unambiguous stimuli that call for only one specific task in a multitasking context), and by introducing the possibility to prepare for an upcoming task (Experiment 2). We found that the inhibitory process is not influenced by a cue informing subjects about the upcoming occurrence of a univalent stimulus. However, the introduction of univalent stimuli allowed preparatory processes to modify the impact of the inhibitory process. Therefore, our results suggest that inhibitory processes are engaged in a rather global manner, not taking into account variations in stimulus valence, which we took as operationalization of critical, conflict-inducing events in the ongoing stream of information processing. However, rare uncritical events, such as univalent stimuli that do not cause conflict and interference in the processing stream, appear to alter the way the cognitive system can take advantage of preparatory processes.