Monitoring and control in multitasking

Error modulates categorization of subsecond durations in multitasking contexts

Monitoring errors consumes limited cognitive resources and can disrupt subsequent task performance in multitasking scenarios. However, there is a dearth of empirical evidence concerning this interference with prospective estimation of time. In this study, we sought to investigate this issue through a serial multitasking experiment, employing a temporal bisection task as the primary task. We introduced two task contexts by implementing two different concurrent tasks. In one context, participants were tasked with discriminating the size difference between two visual items, while in the other context, they were required to judge the temporal order of similar visual items. The primary task remained the same for the entire experiment. Psychophysical metrics, including subjective bias (determined by the bisection point) and temporal sensitivity (measured by the Weber ratio), in addition to reaction time, remained unaltered in the primary task regardless of the perceptual context exerted by the concurrent tasks. However, commission of error in the concurrent tasks (i.e., non-specific errors) led to a right-ward shift in the bisection point, indicating underestimation of time after errors. Applying a drift-diffusion framework for temporal decision making, we observed alterations in the starting point and drift rate parameters, supporting the error-induced underestimation of time. The error-induced effects were all diminished with increasing a delay between the primary and concurrent task, indicating an adaptive response to errors at a trial level. Furthermore, the error-induced shift in the bisection point was diminished in the second half of the experiment, probably because of a decline in error significance and subsequent monitoring response. These findings indicate that non-specific errors impact the prospective estimation of time in multitasking scenarios, yet their effects can be alleviated through both local and global reallocation of cognitive resources from error processing to time processing.

Persisting inhibition biases efficient rule inference under uncertainty

Introduction

Task set inhibition supports optimal switching among tasks by actively suppressing the interference from recently executed competing task sets. It is typically studied in cued task-switching paradigms where there is no uncertainty about the task set or rule to prepare for on each trial. While inhibition has been shown to influence the speed and the accuracy of task execution, affecting task set retrieval, preparation, or implementation in conditions of task set switching, it remains uninvestigated whether it also affects rule selection under uncertainty.

Methods

We implemented an ad-hoc four-rule card sorting task and categorized the rules selected by participants after a rule shift according to the recency of their last usage. We included a measure of working memory capacity (WMC) to control for its involvement in the rule selection process.

Results

Participants exhibited a reduced preference for recently abandoned rules than less recently abandoned ones. Furthermore, we found that such a preference was not associated with WMC.

Discussion

The results suggest that decision-making processes underlying rule inference and selection may be influenced by task-set inhibition, configuring as a conflict adjustment mechanism to the sequential history of rules application.

Inhibition during task switching is affected by the number of competing tasks

Inhibition during task switching is assumed to be indexed by n - 2 repetition costs-that is, performance costs when the task in the current trial equals the task in trial n - 2 (sequences of type ABA) compared with two consecutive switches to another task each (sequences CBA). The present study examined effects of a short-term reduction of the number of candidate tasks on these costs. For this purpose, a variant of the task switching paradigm was used in which in half of the trials, a precue that preceded the task cue allowed for a short-term reduction of the number of candidate tasks. In Experiment 1, one out of three tasks could be excluded. In Experiment 2, one or two out of four tasks could be excluded. Experiment 3 served as control condition using the standard cueing paradigm. Significant n - 2 repetition costs were present with three candidate tasks. In contrast, no costs were visible when the number of candidate tasks was reduced to two. This result is interpreted in terms of a task selection mechanism based on antagonistic constraints among task representations, which operates on a rather superficial level when switching among only two tasks, thereby reducing the need for inhibition.

Influences of cognitive control on number processing: New evidence from switching between two numerical tasks

A growing body of research suggests that basic numerical abilities such as number magnitude and number parity processing are influenced by cognitive control. So far, however, evidence for number processing being influenced by cognitive control came primarily from observed adaptations to stimulus set characteristics (e.g., ratio or order of specific stimulus types) and switches between a numerical and non-numerical task. Complementing this previous research, the present study employed a task switching paradigm exclusively involving numerical tasks (i.e., magnitude comparisons and parity judgements) to examine how cognitive control processes influence number processing. Participants were presented with a single-digit number and had to either judge its parity or compare its magnitude with a standard of 5, depending on a preceding cue. Based on previous results, we expected the numerical distance effect and the spatial-numerical association of response codes (SNARC) effect to be modulated in switch trials requiring the exertion of cognitive control. Partly in line with our expectations, the numerical distance effect was reduced in switch trials. However, no modulation of the SNARC effect was observed. The results pattern suggests that number processing is influenced by cognitive control, depending on task requirements and the type of numerical information (i.e., numerical magnitude vs spatial association of numbers) that is processed. To reconcile the present and previous results, we propose an information prioritisation account, suggesting that cognitive control primarily influences the processing of the information type that requires the most explicit processing.

The effect of inhibitory control and language proficiency on intra-sentential switching costs in reading comprehension

Based on the inhibition account and activation account, inhibitory control and language proficiency play big roles on language control mechanisms underlying language switching respectively. But it is still debatable whether inhibitory control and language proficiency play roles in sentential context during bilingual language comprehension, and how and when they work if they both do. The present study examined the specific roles of language proficiency and inhibitory control on modulating intra-sentential switching costs in Chinese-English bilinguals using self-paced reading task. Results indicated that language proficiency and switching direction modulated intra-sentential switching costs significantly. Switching costs were larger when switching into L1 than into L2 for the first two code-switched words due to inhibitory effect, but more costly switching into L2 than into L1 since the third code-switched words owing to the effect of relative language proficiency. During bilingual language processing, inhibition and activation of languages shaped a dynamic interplay of complementary language control processes. Specifically, inhibitory control and language proficiency work as a dynamic continuum in language switching at sentence level. Switching into L1 requires the release of inhibition to L1, but switching into L2 asks the activation and access of L2. The interaction effects of language proficiency and inhibitory control influenced the exertion and components of inhibition. This study reconciled the independent roles of language proficiency and inhibitory control on language switching and constructed a new continuum based on language proficiency.

Examining post-error performance in a complex multitasking environment

Previous work on indices of error-monitoring strongly supports that errors are distracting and can deplete attentional resources. In this study, we use an ecologically valid multitasking paradigm to test post-error behavior. It was predicted that after failing an initial task, a subject re-presented with that task in conflict with another competing simultaneous task, would more likely miss their response opportunity for the competing task and stay 'tunneled' on the initially errored task. Additionally, we predicted that an error's effect on attention would dissipate after several seconds, making error cascades less likely when subsequent conflict tasks are delayed. A multi-attribute task battery was used to present tasks and collect measures of both post-error and post-correct performance. Results supported both predictions: post-error accuracy on the competing task was lower compared to post-correct accuracy, and error-proportions were higher at shorter delays, dissipating over time. An exploratory analysis also demonstrated that following errors (as opposed to post-correct trials), participants clicked more on the task panel of the initial error regardless of delay; this continued task-engagement provides preliminary support for errors leading to a cognitive tunneling effect.

Modulation of the executive control network by anodal tDCS over the left dorsolateral prefrontal cortex improves task shielding in dual tasking

Task shielding is an important executive control demand in dual-task performance enabling the segregation of stimulus-response translation processes in each task to minimize between-task interference. Although neuroimaging studies have shown activity in left dorsolateral prefrontal cortex (dlPFC) during various multitasking performances, the specific role of dlPFC in task shielding, and whether non-invasive brain stimulation (NIBS) may facilitate task shielding remains unclear. We therefore applied a single-blind, crossover sham-controlled design in which 34 participants performed a dual-task experiment with either anodal transcranial direct current stimulation (atDCS, 1 mA, 20 min) or sham tDCS (1 mA, 30 s) over left dlPFC. Task shielding was assessed by the backward-crosstalk effect, indicating the extent of between-task interference in dual tasks. Between-task interference was largest at high temporal overlap between tasks, i.e., at short stimulus onset asynchrony (SOA). Most importantly, in these conditions of highest multitasking demands, atDCS compared to sham stimulation significantly reduced between-task interference in error rates. These findings extend previous neuroimaging evidence and support modulation of successful task shielding through a conventional tDCS setup with anodal electrode over the left dlPFC. Moreover, our results demonstrate that NIBS can improve shielding of the prioritized task processing, especially in conditions of highest vulnerability to between-task interference.

Disentangling task-selection failures from task-execution failures in task switching: an assessment of different paradigms

Differentiating errors on the basis of the distinct cognitive mechanisms that may have generated them has provided neuropsychologists with useful diagnostic tools. For example, perseverative errors arising from the inability of the patient to set a new criterion for responding are considered one of the hallmarks of cognitive inflexibility. Similarly, in the task-switching paradigm it is possible to distinguish between task-confusion errors, produced by a failure in task selection, and response-confusion errors, arising when the correct task is selected, but the wrong response is given. Nonetheless, only a few studies so far have exploited the existence of different kinds of errors in multitasking situations to inform theories of cognitive flexibility. In the present study, we set out to use a variety of methodologies employed so far in the literature for disentangling errors due to task-selection failure from errors due to task-execution failure. In three experiments, we assessed the capacity of each method to produce error categories that can be mapped as clearly as possible to the cognitive mechanism(s) underlying them using multinomial processing tree modelling. Subsequently, the distinction between task- and response-confusion errors was used to test their differential impact on inhibitory mechanisms in task switching as measured by N-2 repetition costs. Our results are encouraging regarding the possibility of correctly detecting response- and task-selection failures, thus allowing us to assess their differential impact on N-2 repetition costs.

Distinguishing semantic control and phonological control and their role in aphasic deficits: A task switching investigation

People use cognitive control across many contexts in daily life, yet it remains unclear how cognitive control is used in contexts involving language. Distinguishing language-specific cognitive control components may be critical to understanding aphasia, which can co-occur with cognitive control deficits. For example, deficits in control of semantic representations (i.e., semantic control), are thought to contribute to semantic deficits in aphasia. Conversely, little is known about control of phonological representations (i.e., phonological control) in aphasia. We developed a switching task to investigate semantic and phonological control in 32 left hemisphere stroke survivors with aphasia and 37 matched controls. We found that phonological and semantic control were related, but dissociate in the presence of switching demands. People with aphasia exhibited group-wise impairment at phonological control, although individual impairments were subtle except in one case. Several individuals with aphasia exhibited frank semantic control impairments, and these individuals had relative deficits on other semantic tasks. The present findings distinguish semantic control from phonological control, and confirm that semantic control impairments contribute to semantic deficits in aphasia.

Conflict monitoring or multi-tasking? Tracking within-task performance in single-item and multi-item Stroop tasks

Cognitive control is applied in situations that require overriding a habitual and automatic response. The conflict monitoring hypothesis and the Expected Value of Control (EVC) theory as its extension posit a control system responsible for detecting conflicting occasions and adapting to them dynamically within a task. Here we evaluate this prediction in two versions of one of the most popular tasks in cognitive control, namely the Stroop task. We hypothesized that nearby-items interference combines with task interference in the multi-item version effectively turning it into a multi-task that may challenge cognitive control. Adopting an alternative methodology tracking within-task performance, we compared the classical multi-item version of the Stroop task and its single-item counterpart in adults and children. The results revealed a within-task performance decline only in the multi-item version of the task, in both incongruent and neutral conditions, modulated by the presumed maturity of the control system. These findings suggest capacity constraints in control implementation and allocation under conditions requiring parallel execution of multiple cognitive tasks. Task complexity and demands seem to modulate effects on performance. We discuss implications for cognitive control as well as substantial concerns regarding the calculation and use of indices of interference based on the commonly used multi-item version of the Stroop task.

Animal models of action control and cognitive dysfunction in Parkinson's disease

Parkinson's disease (PD) has historically been considered a motor disorder induced by a loss of dopaminergic neurons in the substantia nigra pars compacta. More recently, it has been recognized to have significant non-motor symptoms, most prominently cognitive symptoms associated with a dysexecutive syndrome. It is common in the literature to see motor and cognitive symptoms treated separately and, indeed, there has been a general call for specialized treatment of the latter, particularly in the more severe cases of PD with mild cognitive impairment and dementia. Animal studies have similarly been developed to model the motor or non-motor symptoms. Nevertheless, considerable research has established that segregating consideration of cognition from the precursors to motor movement, particularly movement associated with goal-directed action, is difficult if not impossible. Indeed, on some contemporary views cognition is embodied in action control, something that is particularly prevalent in theory and evidence relating to the integration of goal-directed and habitual control processes. The current paper addresses these issues within the literature detailing animal models of cognitive dysfunction in PD and their neural and neurochemical bases. Generally, studies using animal models of PD provide some of the clearest evidence for the integration of these action control processes at multiple levels of analysis and imply that consideration of this integrative process may have significant benefits for developing new approaches to the treatment of PD.

Adaptive control of working memory

The present study investigated mechanisms of adaptive cognitive control in working memory (WM). WM is conceived as a system for short-term maintenance, updating and manipulation of representations required for goal-directed action. Adaptive control refers to the finding of flexible adjustments of control processes based on conflict. For instance, a higher frequency of incongruent stimuli, that is, stimuli evoking conflicting response tendencies, leads to a higher level of cognitive control as reflected by smaller congruency effects (i.e., the difference between congruent and incongruent items). Likewise, conflict on the previous trial leads to a higher level of cognitive control on the current trial. To investigate adaptive control in WM, we used a modified Sternberg paradigm. Participants memorized two differently colored lists of four digits (i.e., 2 5 7 1), in which corresponding positions in both lists contained the same digits (congruent items) or different digits (incongruent items). Participants were required to make a match/mismatch judgement (Experiment 1 and 2) or to recollect the correct digit at a probed position in one of the two lists (Experiment 3). In all experiments, we could replicate both hallmark effects of adaptive control, the proportion congruency effect, and the congruency sequence effect. Our results strongly support the assumption that WM representations can be dynamically adapted based on the amount of conflict, and that adaptive control of WM follows the same principles that have previously been shown for selective attention.

On the reliability of behavioral measures of cognitive control: retest reliability of task-inhibition effect, task-preparation effect, Stroop-like interference, and conflict adaptation effect

This study examined the reliability (retest and split-half) of four common behavioral measures of cognitive control. In Experiment 1 (N = 96), we examined N – 2 task repetition costs as a marker of task-level inhibition, and the cue-stimulus interval (CSI) effect as a marker of time-based task preparation. In Experiment 2 (N = 48), we examined a Stroop-like face-name interference effect as a measure of distractor interference control, and the sequential congruency effect (“conflict adaptation effect”) as a measure of conflict-triggered adaptation of cognitive control. In both experiments, the measures were assessed in two sessions on the same day, separated by a 10 min-long unrelated filler task. We observed substantial experimental effects with medium to large effect sizes. At the same time, split-half reliabilities were moderate, and retest reliabilities were poor, for most measures, except for the CSI effect. Retest reliability of the Stroop-like effect was improved when considering only trials preceded by congruent trials. Together, the data suggest that these cognitive control measures are well suited for assessing group-level effects of cognitive control. Yet, except for the CSI effect, these measures do not seem suitable for reliably assessing interindividual differences in the strength of cognitive control, and therefore are not suited for correlational approaches. We discuss possible reasons for the discrepancy between robustness at the group level and reliability at the level of interindividual differences.

Further Evidence for the Binding and Retrieval of Control-States From the Flanker Task

In response-interference tasks, congruency effects are reduced in trials that follow an incongruent trial. This congruence sequence effect (CSE) has been taken to reflect top-down cognitive control processes that monitor for and intervene in case of conflict. In contrast, episodic-memory accounts explain CSEs with bottom-up retrieval of stimulus-response links. Reconciling these opposing views, an emerging perspective holds that memory stores instances of control - abstract control-states - creating a shortcut for effortful control processes. Support comes from a study that assessed CSEs in a prime-target task. Here, repeating an irrelevant context feature boosted CSEs, possibly by retrieving previously stored control-states. We present a conceptual replication using the Eriksen flanker task because previous research found that CSEs in the flanker task reflect different control mechanisms than CSEs in the prime-target task. We measured CSEs while controlling for stimulus-response memory effects and manipulated contextual information (vertical spatial location) independently from the stimulus information, which introduced the conflict (horizontal spatial location). Results replicate previous findings - CSEs increased for context-repetition compared to context-changes. This study shows that retrieval of control-states is not limited to a specific task or context feature and therefore generalizes the notion that abstract control parameters are stored into trial-specific event files.

Evaluating students' engagement with an online learning environment during and after COVID-19 related school closures: A survival analysis approach

Background

Due to the COVID-19 pandemic schools all over the world were closed and thereby students had to be instructed from distance. Consequently, the use of online learning environments for online distance learning increased massively. However, the perseverance of using online learning environments during and after school closures remains to be investigated.

Method

We examined German students’ (n ≈ 300,000 students; ≈ 18 million computed problem sets) engagement in an online learning environment for mathematics by means of survival analysis.

Results

We observed that the total number of students who registered increased considerably during and after school closures compared to the previous three years. Importantly, however, the proportion of students engaged also decreased more rapidly over time.

Conclusion

The application of survival analysis provided valuable insights into students’ engagement in online learning - or conversely students’ increased dropout rates - over time. Its application to educational settings allows to address a broader range of questions on students’ engagement in online learning environments in the future.

Limitations of cognitive control on emotional distraction - Congruency in the Color Stroop task does not modulate the Emotional Stroop effect

Emotional information receives prioritized processing over concurrent cognitive processes. This can lead to distraction if emotional information has to be ignored. In the cognitive domain, mechanisms have been described that allow control of (cognitive) distractions. However, whether similar cognitive control mechanisms also can attenuate emotional distraction is an active area of research. This study asked whether cognitive control (triggered in the Color Stroop task) attenuates emotional distraction in the Emotional Stroop task. Theoretical accounts of cognitive control, and the Emotional Stroop task alike, predict such an interaction for tasks that employ the same relevant (e.g., color-naming) and irrelevant (e.g., word-reading) dimension. In an alternating-runs design with Color and Emotional Stroop tasks changing from trial to trial, we analyzed the impact of proactive and reactive cognitive control on Emotional Stroop effects. Four experiments manipulated predictability of congruency and emotional stimuli. Overall, results showed congruency effects in Color Stroop tasks and Emotional Stroop effects. Moreover, we found a spillover of congruency effects and emotional distraction to the other task, indicating that processes specific to one task impacted to the other task. However, Bayesian analyses and a mini-meta-analysis across experiments weigh against the predicted interaction between cognitive control and emotional distraction. The results point out limitations of cognitive control to block off emotional distraction, questioning views that assume a close interaction between cognitive control and emotional processing.

Two types of between-task conflict trigger respective processing adjustments within one dual-task

In dual tasking, two different kinds of between-task conflict occur. Because in both cases, Task 2 characteristics affect Task 1 performance, they are commonly referred to as backward crosstalk effects (BCE): One with a conflict at the response selection stage when Task 1 and Task 2 have dimensional overlap (the compatibility-based BCE) and one with a conflict at the motor execution stage when response inhibition resulting from a Task 2 no-go-trial interferes with simultaneous response execution in Task 1 (the no-go BCE). Recent research suggests that these BCEs differ not only in their underlying cognitive processes, but also in how cognitive control is regulated. Here, we investigated whether both can be produced in a single dual-task set up and whether they trigger their respective processing adjustments (i.e., a sequential modulation). In three experiments, participants categorized numbers as smaller or larger than 5 in Task 1. In Experiments 1 and 2, numbers were responded to irrespective of numerical size (go-response) as Task 2. Further, dimensional overlap was provided by (non)corresponding size information in both stimuli, which was strengthened in Experiment 2 by presenting S1 and S2 in the same/different color in compatible/incompatible trials, respectively. In Experiment 3, participants were required to perform a number-size categorization also in Task 2, establishing strong dimensional overlap by activating the same or different response categories in both tasks. In all three experiments, the number 5 served as the no-go stimulus in Task 2 to induce a no-go BCE on Task 1. By and large, our results show that both types of between-task conflicts not only occur within the same type of BCE, but they also trigger their respective sequential modulation.

A Gratton-like effect concerning task order in dual-task situations

Performing two tasks simultaneously involves the coordination of their processing. Task coordination is particularly required in dual-task situations with varying order of the component tasks. When task order switches between subsequent trials, task-order coordination leads to order switch costs in comparison to task order repetitions (i.e., worse performance in trials associated with an order switch compared to an order repetition). However, the adaptive characteristics of task-coordination processes and order switch costs are underspecified so far. For example, studies on conflict control have shown that these coordination processes can be modulated in response to changes in task demands. The present study investigated therefore whether task-order coordination processes are modulated by the previous experience of a task-order switch. To investigate order switch costs in a dual-task situation with two sensorimotor tasks with variable task-order, we analyzed performance in current trials with task-order switches and with task-order repetitions following task-order switches and task order repetitions in the preceding trial. The data of four different experimental conditions showed that order switch costs were reduced in trials following task-order switches compared to task-order repetitions; resembling the Gratton effect commonly observed in conflict adaptation paradigms. We discussed the present results in the context of task-order set representations, cognitive control theories, and dual-task models.

Multiple Routes to Control in the Prime-Target Task: Congruence Sequence Effects Emerge Due to Modulation of Irrelevant Prime Activity and Utilization of Temporal Order Information

In interference tasks, the magnitude of the congruency effect is reduced in trials that follow an incongruent trial. This congruence sequence effect (CSE) reflects cognitive control processes, yet accounts disagree when and how control is exerted. Here, we address these questions in the context of the prime-target task. In this task, control can either modulate early prime or late target information. Furthermore, control can utilize information specific to the stimulus (perceptual features) or relational information between stimuli (temporal order). Two experiments (N = 41 | N = 62) were conducted using a prime-target task with arrows (prime) and letters (target). We presented either the prime before the target or the target before the prime. For both trial-type transitions, the CSE was assessed. Regarding the first question, when is control exerted, results showed a larger CSE for prime→target relative to target→prime trials. This suggests that control in the prime-target task modulates prime activity. Regarding the second question, how is control exerted, a combined analysis of both experiments showed a larger CSE for repetition of the same prime and target order across two trials (e.g., previous trial: prime→target; current trial: prime→target) compared to changes (e.g., previous trial: prime→target; current trial: target→prime), suggesting that control in the prime-target task can employ temporal selection.

Scaling of the Parameters for Cost Balancing in Self-Organized Task Switching

Previous studies on voluntary task switching using the self-organized task switching paradigm suggest that task performance and task selection in multitasking are related. When deciding between two tasks, the stimulus associated with a task repetition occurred with a stimulus onset asynchrony (SOA) that continuously increased with the number of repetitions, while the stimulus associated with a task switch was immediately available. Thus, the waiting time for the repetition stimulus increased with number of consecutive task repetitions. Two main results were shown: first, switch costs and voluntary switch rates correlated negatively – the smaller the switch costs, the larger the switch rates. Second, participants switched tasks when switch costs and waiting time for the repetition stimulus were similar. In the present study, we varied the SOA that increased with number of task repetitions (SOA increment) and also varied the size of the switch costs by varying the intertrial interval. We examined which combination of SOA increment and switch costs maximizes participants’ attempts to balance waiting time and switch costs in self-organized task switching. We found that small SOA increments allow for fine-grained adaptation and that participants can best balance their switch costs and waiting times in settings with medium switch costs and small SOA increments. In addition, correlational analyses indicate relations between individual switch costs and individual switch rates across participants.

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.

Conflict monitoring and the affective-signaling hypothesis-An integrative review

Conflict-monitoring theory proposes that conflict between incompatible responses is registered by a dedicated monitoring system, and that this conflict signal triggers changes of attentional filters and adapts control processes according to the current task demands. Extending the conflict-monitoring theory, it has been suggested that conflict elicits a negative affective reaction, and that it is this affective signal that is monitored and then triggers control adaptation. This review article summarizes research on a potential signaling function of affect for cognitive control. First, we provide an overview of the conflict-monitoring theory, discuss neurophysiological and behavioral markers of monitoring and control adaptation, and introduce the affective-signaling hypothesis. In a second part, we review relevant studies that address the questions of (i) whether conflict elicits negative affect, (ii) whether negative affect is monitored, and (iii) whether affect modulates control. In sum, the reviewed literature supports the claim that conflict and errors trigger negative affect and provides some support for the claim that affect modulates control. However, studies on the monitoring of negative affect and the influence of phasic affect on control are ambiguous. On the basis of these findings, in a third part, we critically reassess the affective-signaling hypothesis, discuss relevant challenges to this account, and suggest future research strategies.

A Comprehension- or a Production-Based Monitor? Response to Roelofs (2020)

Roelofs (2020) has put forth a rebuttal of the criticisms raised against comprehension-based monitoring and has also raised a number of objections against production-based monitors. In this response, I clarify that the model defended by Roelofs is not a comprehension-based monitor, but belongs to a class of monitoring models which I refer to as production-perception models. I review comprehension-based and production-perception models, highlight the strength of each, and point out the differences between them. I then discuss the limitations of both for monitoring production at higher levels, which has been the motivation for production-based monitors. Next, I address the specific criticisms raised by Roelofs (2020) in light of the current evidence. I end by presenting several lines of arguments that preclude a single monitoring mechanism as meeting all the demands of monitoring in a task as complex as communication. A more fruitful avenue is perhaps to focus on what theories are compatible with the nature of representations at specific levels of the production system and with specific aims of monitoring in language production.

Neural Dynamics of Cognitive Control in Various Types of Incongruence

Conflict-control is a core function of cognitive control. Although numerous studies have considered cognitive control to be domain-general, the shared and distinct brain responses to different types of incongruence or conflict remain unclear. Using a hybrid flanker task, the present study explored the temporal dynamics of brain activation to three types of incongruence: flanker interference, rule-based response switch (rule-switch), and action-based response switch (response-alternation). The results showed that: (1) all three types of incongruence evoked larger N2 amplitudes than the congruent condition in the frontal region, with the N2 amplitudes and topographical distribution of the N2 effect differing between the different types of incongruence; and (2) in the P300 time window, the flanker interference condition yielded the most delayed P300 latency, whereas the rule-switch and response-alternation conditions yielded smaller P300 amplitudes with a longer interval from P300 peak to a keypress. These findings suggest that different types of incongruence are first monitored similarly by the cognitive control system and then resolved differently.

Item-specific proportion congruency (ISPC) modulates, but does not generate, the backward crosstalk effect

When both tasks in a psychological refractory period (PRP) paradigm have compatible manual responses, a compatibility benefit in RT can often be observed on Task1 performance, in apparent violation of a strict traditional response selection bottleneck model. This compatibility-based backward crosstalk effect (BCE) has been generally attributed to automatic activation of Task2 response information, in parallel with attended Task1 performance. This paper tests a potential alternative mechanism of the BCE. Item-specific proportion congruency (ISPC) effects are previously well demonstrated, where learning of associations between stimuli and task conflict (e.g., that particular Stroop items are typically incongruent) allows rapidly and automatically elicited control adjustments in performance. Similar proportion manipulations have recently been shown to modulate the BCE in dual-task performance. If participants could similarly learn associations between particular pairs of stimuli and resulting response conflict in a PRP task, this kind of mechanism could produce relative speeding versus slowing of Task1 RT on response compatible versus incompatible trials. This pattern of data directly describes the BCE, and represents a potential alternative mechanism that does not require any response crosstalk, and would reinforce a stricter view of the response selection bottleneck model, if true. Over two experiments, we demonstrate that while the BCE is sensitive to ISPC-like effects based on Task1 conflict contingencies, the BCE is insensitive to relationships between particular pairs of stimuli and associated conflict. While ISPC effects can modulate the BCE, they do not generate the BCE. These findings reinforce the current Task2 parallel response activation account of the BCE.

Investigating limits of task prioritization in dual-tasking: evidence from the prioritized processing and the psychological refractory period paradigms

Dual-tasking often requires prioritizing one task over the other. For example, in the psychological refractory period (PRP) paradigm, participants are instructed to initially respond to Task 1 (T1) and only then to Task 2 (T2). Furthermore, in the prioritized processing paradigm (PP), participants are instructed to perform T2 only if T1 was a no-go trial-requiring even more prioritization. The present study investigated the limits of task prioritization. Two experiments compared performance in the PRP paradigm and the PP paradigm. To manipulate task prioritization, tasks were rewarded differently (e.g., high reward for T1, low reward for T2, and vice versa). We hypothesized (a) that performance will improve for the highly rewarded task (Experiments 1 and 2) and (b) that there are stronger reward effects for T1 in the PRP than in the PP paradigm (Experiment 2). Results showed an influence of reward on task prioritization: For T1, high reward (compared to low reward) caused a speed-up of responses that did not differ between the two paradigms. However, for T2, reward influenced response speed selectively in the PP paradigm, but not in the PRP paradigm. Based on paradigm-specific response demands, we propose that the coordination of two motor responses plays a crucial role in prioritizing tasks and might limit the flexibility of the allocation of preparatory capacity.

Task Conflict and Task Control: A Mini-Review

Stimulus-driven behaviors are triggered by the specific stimuli with which they are associated. For example, words elicit automatic reading behavior. When stimulus-driven behaviors are incongruent with one’s current goals, task conflict can emerge, requiring the activation of a task control mechanism. The Stroop task induces task conflict by asking participants to focus on color naming and ignore the automatic, stimulus-driven, irrelevant word reading task. Thus, task conflict manifests in Stroop incongruent as well as in congruent trials. Previous studies demonstrated that when task control fails, reaction times in congruent trials slow down, leading to a reversed facilitation effect. In the present mini-review, we review the literature on the manifestation of task conflict and the recruitment of task control in the Stroop task and present the physiological and behavioral signatures of task control and task conflict. We then suggest that the notion of task conflict is strongly related to the concept of stimulus-driven behaviors and present examples for the manifestation of stimulus-driven task conflict in the Stroop task and additional tasks, including object-interference and affordances tasks. The reviewed literature supports the illustration of task conflict as a specific type of conflict, which is different from other conflict types and may manifest in different tasks and under diverse modalities of response.

Measuring Adaptive Control in Conflict Tasks

The past two decades have witnessed an explosion of interest in the cognitive and neural mechanisms of adaptive control processes that operate in selective attention tasks. This has spawned not only a large empirical literature and several theories but also the recurring identification of potential confounds and corresponding adjustments in task design to create confound-minimized metrics of adaptive control. The resulting complexity of this literature can be difficult to navigate for new researchers entering the field, leading to suboptimal study designs. To remediate this problem, we present here a consensus view among opposing theorists that specifies how researchers can measure four hallmark indices of adaptive control (the congruency sequence effect, and list-wide, context-specific, and item-specific proportion congruency effects) while minimizing easy-to-overlook confounds.

Two types of backward crosstalk: Sequential modulations and evidence from the diffusion model

In multitasking, the backward crosstalk effect (BCE) means that Task 1 performance is influenced by characteristics of Task 2. For example, (1) RT1 is shorter when the two responses are given on the same (compatible trial) compared with opposite sides (incompatible conflict-trial; compatibility-based BCE), and (2) RT1 is longer when Task 2 is a no-go relative to a go task (no-go BCE). We investigated the impact of recently experienced trial and conflict history on the size of such BCEs. Similar to the Gratton effect in standard conflict tasks, clear sequential modulations were observed for the two kinds of BCEs, which were present following (1) compatible trials and (2) go-trials and inverted following (1) incompatible and (2) no-go trials. Furthermore, recent evidence from mental chronometry studies suggests that the compatibility-based BCE is located inside the response selection stage, while the no-go-based BCE arises in motor execution. Against this background, a diffusion model analysis was carried out to reveal the reason(s) for the sequential modulations. As expected, for the compatibility-based BCE, changes in drift rate explain the sequential modulations, but for the no-go BCE changes in non-decision time are important. The present results indicate that both BCEs not only differ fundamentally in their underlying processes, but also in the way cognitive control is adjusted.

Smaller backward crosstalk effects for free choice tasks are not the result of immediate conflict adaptation

In dual-task situations, mutual interference phenomena are often observed. One particularly interesting example of such phenomena is that even Task 1 performance is improved if Task 2 requires a compatible (e.g., both responses are given on the left side) instead of an incompatible response (e.g., one response is given on the right side, and the other on the left side). This is called the compatibility-based backward crosstalk effect (BCE). In a previous paper, we observed support for a critical role of stimulus-response (S-R) links in causing this effect: The BCE was smaller when one of the two tasks was a free choice task. However, an alternative explanation for this observation is that free choice tasks lead to immediate conflict adaptation, thereby reducing the interference from the other task. In the present two experiments, we tested this explanation by varying the amount of conflict assumed to be induced by a free choice task either sequentially (Exp. 1) or block-wise (Exp. 2). While we replicated a sequential modulation of the BCE with two forced choice tasks, we observed (1) no reduction of the BCE induced by (compatible) free choice trials nor (2) an effect of block-wise manipulations of the frequency of free choice trials on the size of the BCE. Thus, while the BCE is sensitive to sequential modulations induced by the (in)compatibility of two forced choice responses, which might point to conflict adaptation, the reduced BCE in dual-task situations involving a free choice task is likely due to its weaker S-R links.