Research Grant (FI 1624/8-1) by the German Research Foundation (DFG), 2023-2026
Principal investigator: Rico Fischer (Co-PI Gesine Dreisbach, PhD, University of Regensburg)

Adaptive control forms the basis of cognitive and behavioral flexibility. It is sensitive to normal aging and its malfunction is closely related to neurological and psychiatric conditions. In general, human beings have the astonishing ability to flexibly adapt action and thought in response to changing requirements from the environment. At the same time, they can be surprisingly stuck in set, for example when they continue using a formerly successful but no longer adaptive processing strategy. Such stuck-in-set phenomena, originally reported in problem solving tasks (Luchins, 1942), are not restricted to neuropsychological abnormalities like perseveration in frontal lobe patients but have recently also been reported for control strategies in context processing- and response conflict-tasks in healthy individuals (e.g., Abrahamse, Duthoo, Notebaert, & Risko, 2013; Hefer & Dreisbach, 2017). In this research project, we intend to investigate two so far highly neglected phenomena that expose a weakness of the much-vaunted cognitive flexibility: (1) The asymmetrical costs when switching between a shielded and a more relaxed mode of control, which show that it can be harder to let go from a shielding control mode and switch to a more relaxed control mode than vice versa.  And (2) the observation that the flexibility to adapt control to different context demands is further limited by the volatility and frequency of context changes. The importance of adaptive control for cognitive and behavioral flexibility highlights the need for understanding the underlying cognitive mechanisms (e.g., the flexible (dis)engagement of different control states), which may offer fertile grounds for subsequent translational research. 

Research Grant (FI 1624/6-1, Project P7) within the Research Unit (Forschungsgruppe) FOR 5429/1 „Modulation of brain networks for memory and learning by transcranial electrical brain stimulation: A systematic, lifespan approach“ funded by the German Research Foundation (DFG), 2023-2027
Principal investigator: Rico Fischer (Co-PI Marcus Meinzer, PhD, University Medicine Greifswald)

Adaptive cognitive control – as the human capacity to pursue goal-directed behavior in dynamically changing environments – forms the basis for cognitive and behavioral flexibility in everyday life. Recent research has highlighted associative learning mechanisms and the role of episodic memory as basic mechanisms underlying adaptive cognitive control. Because adaptive cognitive control shows a decline in normal aging and its malfunction is closely related to neurological and psychiatric conditions, this project will specifically investigate the neural mechanisms and predictors underlying enhancement of this process by individualized, focal transcranial direct current stimulation (tDCS). In the long-run, outcomes of this project will contribute to improving treatment of patients with deficits in self-control and disadvantageous decision making (e.g., addiction, eating disorders).

Within the broader context of the Research Unit (RU), the present study is one of eight projects investigating tDCS effects on learning and memory formation across functional domains (Projects 1-8) and the healthy human lifespan. The highly systematic and coordinated approach pursued by these empirical projects will allow for the first time analyzing the underlying neural mechanisms and predictors of behavioral stimulation response not only within each project, but also across the different tasks and functional domains (in Project 9).

The current project will contribute unique information on how tDCS modulates learning-based adaptive cognitive control, thereby complementing the investigation of tDCS-induced enhancement of sequential decision making in Project 8 (PI Li). Collectively, the results of the empirical projects of the RU will increase our current understanding of tDCS-induced neural network effects, their regional specificity, the mechanisms underlying inter-individual variability of stimulation effects, and potential changes due to chronological age. From a methodological point of view, data acquired in these projects will contribute to optimizing and validating biophysical models of current flow (in P9+10), thereby advancing future experimental and translational applications of tDCS in health and disease.

Research grant (FI 1624/5-1) by the German Research Foundation (DFG), 2020-2023
Principal investigator: Rico Fischer (Co-PI: Roman Liepelt, PhD)

This project aims at filling the gap between basic cognitive research on multiple task performance on the one hand and current developments of applied dual-tasking demands in technical environments on the other. Recent research in cognitive psychology has substantiated the assumption of a strong connection between action components directly affecting perception and attentional control. Such action-perception interactions are increasingly prevalent in high-demanding complex cognitive tasks, which require the simultaneous processing and coordination of multiple stimuli and responses. Especially in real-life and applied contexts, task control is often implemented via handheld devices or touch screens and thus, the visual-manual interaction focus is shifted into a shared visuo-spatial attentional region. This project builds on recent findings in our labs that stimulus-hand nearness indeed improves dual tasking performance. This near-hand benefit was expressed in improved shielding of the prioritized task against interference by additional task processing (i.e., reduced between-task interference) when hands were located close to the stimuli compared to when they were located far from the stimuli. This is a highly important step in this new research area, as it offers possibilities for optimizing dual tasking in conditions of stimulus-hand nearness. At the same time, however, the cognitive mechanisms underlying these findings of improved dual tasking are to date highly underspecified. We reason that traditional theoretical assumptions about mechanisms underlying the action-perception interactions cannot be easily transferred to situations of multiple task performance. Instead, we propose that in dual-task conditions, in which each task-specific stimulus is operated with the respective task-specific response hand, the nearness of the hand to the stimulus will facilitate perception-action coupling in each task and will thus, facilitate the conceptual separation of two tasks. As a consequence, we propose that presenting stimuli close to the hands will help to reduce unwanted information-transmission between tasks (between-task interference). The present project aims at testing and confirming this assumption in three work-packages that include the investigation of the type of interference that can be reduced, the identification of the underlying mechanisms, the modality-specificity and the transfer of the near-hand-benefit effect to applied and real-life dual-task scenarios using hand-held devices, tool-based and hand-movement responses. The present approach of addressing action-perception interactions in dual tasking will therefore not only provide important theoretical scientific information on how stimulus-hand proximity affects dual-task performance costs, but promises also important knowledge for transfer into applied cognitive sciences and technical developments.

Research Grant within the Priority Program "Multitasking" (SPP 1771) by the German Research Foundation (DFG), 2015-2018 
Principal investigator: Rico Fischer (Co-PI Roman Liepelt, PhD)

Multiple task performance has become an increasing prevalent phenomenon of the modern world, as we face a constantly growing demand on multitasking abilities in everyday and work life. For example, the development of modern technical devices more and more demand visual-manual interactions within a shared visuo-spatial region (e.g., hand-held devices, tablet control), which are continuously implemented in complex real life multitasking environments, such as in cockpits of trains and aircrafts. From research in embodied cognition, however, it is known, that cognitive processing is not independent of the body. Recent research demonstrated that the presence of hands close to a visual stimulus (e.g., within the visuo-spatial attentional focus) biases the allocation of attention to the area near the hand and enhances the engagement of cognitive control for stimuli in near hand space.

In the special context of dual tasks, with multiple stimuli being presented in near hand space, we aim at specifying which control parameters are affected in proximal stimulus conditions. We therefore ask, whether altered visuo-spatial attention targets S1 and S2 equally within left- and right-hand space and how hand position determines cognitive control parameters relating to central switching operations, i.e.,task set shifts at the bottleneck. A more thorough and in-depth processing of the currently relevant stimulus under proximal stimulus conditions might delay disengagement and shifts to secondary task component processing. Furthermore, we assess the impact of privileged stimulus processing in near hand space on priorization of task order and the flexibility of reconfiguration of task order switches. By measuring hand proximity effects on dual-task performance, we aim to provide a new research perspective on human multitasking behavior by emphasizing the role of action-perception interaction for determining cognitive control in dual-task situations. An embodied cognition approach to multitasking will, therefore, not only provide important theoretical scientific information concerning the flexibility of cognitive control for the coordination and scheduling of task sets in dual-task situations but might provide fertile grounds for transfer into applied cognitive sciences and technical developments. Finally, we think that this project will provide a valuable asset to the SPP 1772 in furthering the understanding of flexible priorization and shifting between component processing of multiple task sets.

Research grant (Project A3) within the Collaborative Research Center (SFB) 940 "Volition and Cognitive Control" by the German Research Foundation (DFG), 2012-2016
Principal investigator: Rico Fischer

Adaptive action control requires the dynamic adjustment between complementary control demands. While task-irrelevant stimuli need to be ignored and blocked from being processed in order to prevent interference with task-relevant processing (goal shielding), complete shielding is dysfunctional and even potentially harmful, as it would prevent the individual from monitoring the environment for potentially relevant stimuli (background monitoring) that may signal a change in action goal (e.g., stimuli that imply danger). Instead, a dynamic regulation of these complementary control processes is required, reflecting a tradeoff between antagonistic constraints. This dynamic regulation of cognitive control processes, however, is to date only insufficiently understood.

The present project set out to target this question by asking, how control is regulated to meet the requirements in a dynamically changing environment. We particularly applied a dual-task approach, because dual tasking constitutes a prime example of a control dilemma. It requires an individual to maintain a balance between two antagonistic types of performance optimization, i.e., minimizing between-task interference (by increasing serial task processing) and minimizing mental effort (by allowing for more parallel processing). Flexibly adjusting the degree of more serial versus more parallel dual-task processing to changing task and context requirements reflects high levels of adaptability in dynamic environments.

In the present project we investigated the adjustment of more parallel versus more serial task processing. We claimed that cognitive control parameters in dual tasking are not only determined by voluntary top-down regulation due to task instructions (of how to perform the dual task), but importantly that substantial bottom-up regulation of cognitive control enables the adoption of certain task processing modes. Three study lines were proposed, in which statistical contingencies were manipulated in a context (location)-specific manner (e.g., likelihood of between-task interference). The goal was to demonstrate that these bottom-up features are detected and are capable to trigger associated control states that determine the degree of parallel versus serial task processing.

Research grant (FI 1624/2-1) by the German Research Foundation (DFG), 2010-2014 
Principal investigator: Rico Fischer

Alerting warning signals are meant to optimize behavior in complex and error prone human-machine interactions and are thus often found in vehicles as “Lane Departure Warning Systems”, “Vehicle Headway Sensors”, or “Reverse Parking Sensors”. In recent research, however, we could show that alerting signals are especially beneficial in the initiation of reflexive response tendencies, which results in increased response conflicts when two response alternatives compete for control of action. Such increased interference effects have been explained by alerting signals impairing executive control or widening the scope of visual attention. In contrast, we interpret this finding as an alerting signal based enhanced memory retrieval process on the basis of acquired stimulus-response (S-R) links. In recent studies we could show that the alerting-increased interference effects critically depend on the existence of S-R links and that alerting signals reduced neural activity in primary visual cortex. We assume that alerting signals trigger a shift in cognitive control engagement to a stronger reliance on habitual memory-based reflex-behavior that may be accompanied with an increase of efficiency in information transmission from lower to higher cortices.