Adjustments In Cognitive Control Research Articles

Error-preceding brain activity reflects (mal-)adaptive adjustments of cognitive control: a modeling study.

Errors in choice tasks are preceded by gradual changes in brain activity presumably related to fluctuations in cognitive control that promote the occurrence of errors. In the present paper, we use connectionist modeling to explore the hypothesis that these fluctuations reflect (mal-)adaptive adjustments of cognitive control. We considered ERP data from a study in which the probability of conflict in an Eriksen-flanker task was manipulated in sub-blocks of trials. Errors in these data were preceded by a gradual decline of N2 amplitude. After fitting a connectionist model of conflict adaptation to the data, we analyzed simulated N2 amplitude, simulated response times (RTs), and stimulus history preceding errors in the model, and found that the model produced the same pattern as obtained in the empirical data. Moreover, this pattern is not found in alternative models in which cognitive control varies randomly or in an oscillating manner. Our simulations suggest that the decline of N2 amplitude preceding errors reflects an increasing adaptation of cognitive control to specific task demands, which leads to an error when these task demands change. Taken together, these results provide evidence that error-preceding brain activity can reflect adaptive adjustments rather than unsystematic fluctuations of cognitive control, and therefore, that these errors are actually a consequence of the adaptiveness of human cognition.

Right Ventrolateral Prefrontal Cortex Mediates Individual Differences in Conflict-driven Cognitive Control

Conflict adaptation--a conflict-triggered improvement in the resolution of conflicting stimulus or response representations--has become a widely used probe of cognitive control processes in both healthy and clinical populations. Previous fMRI studies have localized activation foci associated with conflict resolution to dorsolateral PFC (dlPFC). The traditional group analysis approach employed in these studies highlights regions that are, on average, activated during conflict resolution, but does not necessarily reveal areas mediating individual differences in conflict resolution, because between-subject variance is treated as noise. Here, we employed a complementary approach to elucidate the neural bases of variability in the proficiency of conflict-driven cognitive control. We analyzed two independent fMRI data sets of face-word Stroop tasks by using individual variability in the behavioral expression of conflict adaptation as the metric against which brain activation was regressed while controlling for individual differences in mean RT and Stroop interference. Across the two experiments, a replicable neural substrate of individual variation in conflict adaptation was found in ventrolateral PFC (vlPFC), specifically, in the right inferior frontal gyrus, pars orbitalis (BA 47). Unbiased regression estimates showed that variability in activity in this region accounted for ∼ 40% of the variance in behavioral expression of conflict adaptation across subjects, thus documenting a heretofore unsuspected key role for vlPFC in mediating conflict-driven adjustments in cognitive control. We speculate that vlPFC plays a primary role in conflict control that is supplemented by dlPFC recruitment under conditions of suboptimal performance.

The bivalency effect: adjustment of cognitive control without response set priming

The occasional occurrence of bivalent stimuli, that is, stimuli with features relevant to two tasks, slows performance on subsequent tasks with univalent stimuli, including those which have no common features with bivalent stimuli (i.e., the "bivalency effect"). We have suggested that the bivalency effect might stem from an episodic context binding arising from the occasional occurrence of bivalent stimuli. However, as the same response set is used usually for univalent and bivalent stimuli, bivalent stimulus features may be negatively primed via response features. We investigated this possibility in two experiments, in which one group of participants used the same response keys for all tasks and another group used separate response keys. The results showed a comparable bivalency effect in both groups. Thus, it rather results from episodic context binding than from response set priming.

Substantia Nigra Activity Level Predicts Trial-to-Trial Adjustments in Cognitive Control

Effective adaptation to the demands of a changing environment requires flexible cognitive control. The medial and the lateral frontal cortices are involved in such control processes, putatively in close interplay with the BG. In particular, dopaminergic projections from the midbrain (i.e., from the substantia nigra [SN] and the ventral tegmental area) have been proposed to play a pivotal role in modulating the activity in these areas for cognitive control purposes. In that dopaminergic involvement has been strongly implicated in reinforcement learning, these ideas suggest functional links between reinforcement learning, where the outcome of actions shapes behavior over time, and cognitive control in a more general context, where no direct reward is involved. Here, we provide evidence from functional MRI in humans that activity in the SN predicts systematic subsequent trial-to-trial RT prolongations that are thought to reflect cognitive control in a stop-signal paradigm. In particular, variations in the activity level of the SN in one trial predicted the degree of RT prolongation on the subsequent trial, consistent with a modulating output signal from the SN being involved in enhancing cognitive control. This link between SN activity and subsequent behavioral adjustments lends support to theoretical accounts that propose dopaminergic control signals that shape behavior both in the presence and in the absence of direct reward. This SN-based modulatory mechanism is presumably mediated via a wider network that determines response speed in this task, including frontal and parietal control regions, along with the BG and the associated subthalamic nucleus.

The dynamics of cognitive control: Evidence for within‐trial conflict adaptation from frequency‐tagged EEG

A central topic in the cognitive sciences is how cognitive control is adapted flexibly to changing task demands. Conflict monitoring theory originally proposed conflict triggered adjustments of cognitive control after a conflict trial to improve subsequent performance. In the present study, we tested the hypothesis that readjustments of cognitive control occur continuously within a conflict trial itself. Using frequency tagged electroencephalogram in a flanker task, we traced the allocation of attention to target and distracter stimuli. We found evidence for a conflict-triggered within-trial contrast enhancement dissociating target and distracters. This contrast enhancement vanished for consecutive trials with constant tagging frequencies, indicating that trial-to-trial conflict adaptation effects may, at least partly, be the product of interacting processes serving conflict resolution within trials.

Top-down and bottom-up deficits in conflict adaptation after frontal lobe damage

The ability to adaptively control our responses to conflicting information is crucial if we are to respond in a flexible manner to the environment. The “conflict monitoring model” proposes that the prefrontal cortex is responsible of reactive adjustments in cognitive control. We present neuropsychological data contrasting the performance of patients with prefrontal lesions with the one exhibited by patients with lesions outside the frontal lobe and nonlesioned participants, on the processes involved in the dynamic adaptation to conflicting stimulus information. Relative to both lesioned and nonlesioned control groups, prefrontal patients were impaired in adapting to conflict when all features of the conflicting stimuli and their associated responses changed on consecutive trials. However, the prefrontal patients also showed an unusually large conflict adaptation effect when the stimuli and/or response features repeated across trials. We conclude that prefrontal cortex is relevant both for genuine “top-down” conflict monitoring and for regulating the influence of “bottom-up” responses based on the integration of stimulus features across trials.

Working-memory-triggered dynamic adjustments in cognitive control.

Dynamic adjustments in cognitive control are well documented in conflict tasks, wherein competition from irrelevant stimulus attributes intensifies selection demands and leads to subsequent performance benefits. The current study investigated whether mnemonic demands, in a working memory (WM) task, can drive similar online control modifications. Demand levels (high vs. low) of WM maintenance (memory load of 2 items vs. 1 item) and delay-spanning distractor interference (confusable vs. not confusable with memoranda) were manipulated using a factorial design during a WM delayed-recognition task. Performance was best subsequent to trials in which both maintenance and distractor interference demands were high, followed by trials with high demand in either of these 2 control domains, and worst following trials with low demand in both domains. These results suggest that dynamic adjustments in cognitive control are not triggered exclusively by conflict-specific contexts but are also triggered by WM demands, revealing a putative mechanism by which this system configures itself for successful task performance.

Adjustments of conflict monitoring in Parkinson's disease.

In Stroop-like tasks, the detection of conflict triggers adjustments of cognitive control to reduce conflict in subsequent trials. The present study tested the hypothesis of an impaired modulation of conflict monitoring in Parkinson's disease (PD). 18 PD patients and 18 healthy control (HC) participants performed a Stroop-like task in 2 conditions differing in terms of incongruent/congruent stimuli ratio. HC participants demonstrated a sustained modulation of interference effect, the interference effect being decreased when the proportion of incongruent stimuli was high. A trial-by-trial analysis also showed that in the HC group, processing an incongruent stimulus reduced interference in the subsequent trial. Unlike controls, PD patients did not demonstrate any transient or sustained reduction of the interference effect. Within the framework of recent models, these results can be interpreted as an impairment of a proactive mode of cognitive control in patients with PD.

Conflict adaptation and cognitive control adjustments following traumatic brain injury

Survivors of severe traumatic brain injury (TBI) often demonstrate impairments in the cognitive control functions of detecting response conflict and signaling for recruitment of cognitive resources to appropriately adjust performance. These cognitive control functions can be measured using conflict adaptation effects, wherein manifestations of conflict detection and processing are reduced following high- relative to low-conflict trials. Event-related potentials (ERPs) were collected while 18 survivors of severe traumatic brain injury (TBI) and 21 demographically matched control participants performed a modified Stroop task. The incongruent-minus-congruent trial Stroop effect for trials preceded by incongruent (high conflict) and congruent (low conflict) trials were compared for behavioral (response time [RT] and error rate) and ERP reflections of cognitive control. Behavioral data showed a reduction in the Stroop effect for both control and TBI participant RTs when preceded by incongruent trials. The magnitude of these effects did not differentiate control and TBI participants. ERP data revealed a centro-parietal conflict slow potential (conflict SP) that differentiated incongruent from congruent trials. Planned comparisons showed a decreased amplitude conflict SP when ERPs were preceded by incongruent trials in control, but not TBI participants. Results indicate subtle TBI-related impairments in conflict resolution mechanisms in the context of intact RT-related conflict adaptation.

Specific effects of acute moderate exercise on cognitive control

The main issue of this study was to determine whether cognitive control is affected by acute moderate exercise. Twelve participants [4 females (VO 2 max = 42 ml/kg/min) and 8 males (VO 2 max = 48 ml/kg/min)] performed a Simon task while cycling at a carefully controlled workload intensity corresponding to their individual ventilatory threshold. The distribution-analytical technique and the delta plot analysis [Ridderinkhof, K. R. (2002). Activation and suppression in conflict tasks: Empirical clarification through distributional analyses. In W. Prinz & B. Hommel (Eds.), Common mechanisms in perception and action. Attention and performance (Vol. 19, pp. 494–519). Oxford: Oxford University Press.] were used to assess the role of selective response inhibition in resolving response conflict. Results showed that cognitive processes appeared to be differently affected by acute moderate exercise. Reaction time results confirmed that performance is better (faster without change in accuracy) when the cognitive task is performed simultaneously with exercise. Between-trial adjustments (post-conflict and post-error) highlighted that cognitive control adjustments are also fully efficient during exercise. However, the effect of congruency (Simon effect) appeared to be more pronounced during exercise compared to rest which suggests that the response inhibition is deteriorated during exercise. The present findings suggest that acute moderate exercise differently affects some specific aspects of cognitive functions.

How task representations guide attention: Further evidence for the shielding function of task sets.

To pursue goal directed behavior, the cognitive system must be shielded against interference from irrelevant information. Aside from the online adjustment of cognitive control widely discussed in the literature, an additional mechanism of preventive goal shielding is suggested that circumvents irrelevant information from being processed in the first place. Participants had to react to 8 different words depicting clothing items that were presented in front of line drawings that could be either semantically related (clothes) or unrelated (animals with spatial orientation) to the target words. Participants either learned the stimulus-response (S-R) mappings by heart or used 1 task set (TS). In the S-R group, semantically related and unrelated distractors interfered with performance, whereas in the TS group, only semantically related distractors interfered, and unrelated distractors had no effect. It follows that task representations based on a general TS help to focus attention on relevant information, thereby preventing the processing of irrelevant information.

Context-sensitive adjustments of cognitive control: Conflict-adaptation effects are modulated by processing demands of the ongoing task.

Dynamic adjustments of cognitive control in response to interference from irrelevant stimulus attributes have repeatedly been shown. The purpose of the current research was to investigate how these control adjustments are modulated by the processing demands of a primary task. To this end, the authors combined a primary task (a number comparison task: classifying digits as smaller or larger than 5) with a Simon task. Control adjustments were observed in the form of typical sequential modulations of the Simon effect. In addition, the authors found sequential modulations of the numerical distance effect and an interaction of both effects. Results suggest that not only response conflict due to interference from task-irrelevant features but also processing demands of task-relevant features determine the level of control adjustment in the subsequent trial.

Contextual Adjustments in Cognitive Control Across Tasks

Does encountering information-processing conflict recruit general mechanisms of cognitive control or change only the representations of specific cues and responses? In the present experiments, a flanker task elicited responses to symbolic information (arrow meaning), whereas Stroop-like tasks elicited responses to nonsymbolic information (color of a letter or location of a target box). Despite these differences, when participants performed the flanker and Stroop tasks intermittently in randomized orders, the extent of information-processing conflict encountered on a particular trial modulated performance on the following trial. On across-task trial pairs, increases in response time to incongruent relative to congruent stimulus arrays were smaller immediately following incongruent trials than immediately following congruent trials. The degree of cognitive control exerted on a particular task thus appears to reflect not only the quality, but also the quantity, of recent experiences of information-processing conflict.

Congruency sequence effects and cognitive control

Congruency effects in selective attention tasks are subject to sequential modulation: They are smaller following an incongruent stimulus than following a congruent one. This congruency sequence effect has been interpreted as reflecting conflict-driven adjustments in cognitive control (conflict adaptation) or, alternatively, episodic memory effects of stimulus-response association (feature integration). The present article critically reviews support for these rival accounts in the experimental literature and discusses the implications thereof for assessing behavioral and neural signatures of cognitive control processes. It is argued that both conflict adaptation and feature integration contribute to the congruency sequence effect but that their respective contributions can be isolated experimentally. Studies that have pursued this isolation strategy have gained important insights into cognitive control processes. Finally, other factors, such as expectancies, may also contribute to the congruency sequence effect, and thus their potential role needs to be carefully examined and, if found significant, integrated into current models of cognitive control.

Tracking the Temporal Dynamics of Updating Cognitive Control: An Examination of Error Processing

In 2 experiments, we used event-related brain potentials (ERPs) to examine the temporal dynamics of neural processes related to adjustments of cognitive control following errors in the counting Stroop task. The ERPs elicited by errors revealed the error-related negativity (ERN) and error positivity consistent with a large body of literature. In addition, errors were associated with a frontal slow wave between 200 and 2000 ms after the response that was consistent with the activity of neural generators in the lateral frontal cortex. The ERN and frontal slow wave were correlated with posterror slowing of response time and positive affect (i.e., happiness and calmness) during task performance. These data are consistent with the idea that interactions between anterior cingulate cortex and lateral frontal cortex support adjustments of cognitive control and that this neural network is sensitive to the influence of affect experienced during task performance.

Cognitive Control Dynamics for Reaching a Satisficing Performance in Complex Dynamic Situations

The study of dynamic situations, in which the human operator can exert only partial control (such as in industrial process control, aircraft piloting, or air traffic control), has offered rare opportunities to examine the dynamics of cognitive control. Unlike most of the laboratory approaches to the study of cognition, this kind of study has stressed that several cognitive modes can act in parallel and that the distribution of control among the modes can evolve over time in relation to task requirements and human operator states. This article is a review of the arguments, developed in the literature on dynamic situations and by the authors themselves, in favor of a dynamic adjustment of cognitive control to situational features (integrating both the environment and the human) as a major component of adaptation. The main criterion used by the human operator to adjust cognitive control is situation mastery, as a guarantee that a satisficing performance will be reached with an acceptable quantity of resources. Two main dimensions are proposed to characterize cognitive control modes: the level of abstraction (symbolic/subsymbolic) and the origin (internal-anticipative, external-reactive) of the data used for control. Metacognition is considered as a means to distribute the cognitive control within these dimensions in order to ensure situation mastery. Theoretical, methodological, and practical implications of this perspective on cognitive control dynamics are drawn. From a theoretical viewpoint, the approach stresses the need to consider the cognitive system degrees of freedom to adapt to situations, and that therefore several solutions are possible in order to perform the same task. On the methodological side, the access to the diverse cognitive control modes, to their parallelism, and to the cognitive control dynamics requires new methodological approaches. The practical implications consist in developing support systems that keep the degrees of freedom open for adaptation and in trying to manage consistency.

The Regulation of Cognitive Control following Rostral Anterior Cingulate Cortex Lesion in Humans

The contribution of the medial prefrontal cortex, particularly the anterior cingulate cortex (ACC), to cognitive control remains controversial. Here, we examined whether the rostral ACC is necessary for reactive adjustments in cognitive control following the occurrence of response conflict [Botvinick, M. M., Braver, T. S., Barch, D. M., Carter, C. S., & Cohen, J. D. Conflict monitoring and cognitive control. Psychological Review, 108, 624-652, 2001]. To this end, we assessed 8 patients with focal lesions involving the rostral sector of the ACC (rACC patients), 6 patients with lesions outside the frontal cortex (non-FC patients), and 11 healthy subjects on a variant of the Simon task in which levels of conflict were manipulated on a trial-by-trial basis. More specifically, we compared Simon effects (i.e., the difference in performance between congruent and incongruent trials) on trials that were preceded by high-conflict (i.e., incongruent) trials with those on trials that were preceded by low-conflict (i.e., congruent) trials. Normal controls and non-FC patients showed a reduction of the Simon effect when the preceding trial was incongruent, suggestive of an increase in cognitive control in response to the occurrence of response conflict. In contrast, rACC patients attained comparable Simon effects following congruent and incongruent events, indicating a failure to modulate their performance depending on the conflict level generated by the preceding trial. Furthermore, damage to the rostral ACC impaired the posterror slowing, a further behavioral phenomenon indicating reactive adjustments in cognitive control. These results provide insights into the functional organization of the medial prefrontal cortex in humans and its role in the dynamic regulation of cognitive control.

Preparatory adjustment of cognitive control in the task switching paradigm

In this article, the authors investigate the assumption that preparation while switching between cognitive tasks is dynamically adjusted to the current task demands. Performance in high-shift blocks (75% shifts) was compared with performance in high-repetition blocks (75% repetitions). This probability information was given either at the beginning of a block (global condition) or by specific probability cues before every trial (local condition). The authors report strong preparation effects (activation of the probable task and inhibition of the improbable task) in high-shift blocks, especially when specific probability cues were provided. In high-repetition blocks, however, the preparation effects were less pronounced. The results support the assumption that preparation is dynamically adjusted to the expected task requirements.

Adjustments of Cognitive Control in Younger and Older Adults

The effects of aging on behavioral and electrophysiological indices of adjustments of cognitive control were examined in two experiments. Specifically, we considered the effects of aging of patterns of response time and modulations of the event-related brain potentials (ERPs) on sequential trial effects, error-related slowing, and local switch costs in two modified Stroop tasks. The behavioral data reveal that sequential trial effects were observed when color, but not word, identification was required and that these effects were similar in younger and older adults; that the degree of error-related slowing was similar for younger and older adults in Experiment 1 and greater in older than younger adults in Experiment 2; that local switch costs in response time were similar in younger and older adults and that the requirement to switch between color and word identification resulted in a dramatic increase in the number of color intrusion errors in older adults in Experiment 2. The ERP data revealed that endogenously generated adjustments of cognitive control were associated with a parietal slow wave that mirrored the behavioral data and was similar in amplitude in younger and older adults and an anterior frontal slow wave that was absent in older adults. The ERP data also revealed that an enhancement of the P3 component and a frontal slow wave that differentiated color switch trials from color non-switch and word trials in younger adults were attenuated in older adults.

The neural correlates and functional integration of cognitive control in a Stroop task

It is well known that performance on a given trial of a cognitive task is affected by the nature of previous trials. For example, conflict effects on interference tasks, such as the Stroop task, are reduced subsequent to high-conflict trials relative to low-conflict trials. This interaction effect between previous and current trial types is called “conflict adaptation” and thought to be due to processing adjustments in cognitive control. The current study aimed to identify the neural substrates of cognitive control during conflict adaptation by isolating neural correlates of reduced conflict from those of increased cognitive control. We expected cognitive control to be implemented by prefrontal cortex through context-specific modulation of posterior regions involved in sensory and motor aspects of task performance. We collected event-related fMRI data on a color-word naming Stroop task and found distinct fronto-parietal networks of current trial conflict detection and conflict adaptation through cognitive control. Conflict adaptation was associated with increased activity in left middle frontal gyrus (GFm) and superior frontal gyrus (GFs), consistent with increased cognitive control, and with decreased activity in bilateral prefrontal and parietal cortices, consistent with reduced response conflict. Psychophysiological interaction analysis (PPI) revealed that cognitive control activation in GFs and GFm was accompanied by increased functional integration with bilateral inferior frontal, right temporal and parietal areas, and the anterior cerebellum. These data suggest that cognitive control is implemented by medial and lateral prefrontal cortices that bias processes in regions that have been implicated in high-level perceptual and motor processes.