Gratton Effect Research Articles

The DLPFC is centrally involved in resolving Stroop conflicts, suppressing distracting sensory input within the auditory and visual system.

Cognitive control is a prerequisite for successful, goal-oriented behavior. The dorsolateral prefrontal cortex (DLPFC) is assumed to be a key player in applying cognitive control; however, the neural mechanisms by which this process is accomplished are still unclear. To further address this question, an audiovisual Stroop task was used, comprising simultaneously presented pictures and spoken names of actors and politicians. Depending on the task block, participants had to indicate whether they saw the face or heard the name of a politician or an actor (visual vs. auditory blocks). In congruent trials, both stimuli (visual and auditory) belonged to the same response category (actor or politician); in incongruent trials, they belonged to different categories. During this task, activity in sensory target regions was measured via functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG), respectively. Specifically, fNIRS was used to monitor activity levels within the auditory cortex, while the EEG-based event-related potential of the N170 was considered as a marker of FFA (fusiform face area) involvement. Additionally, we assessed the effects of inhibitory theta-burst stimulation-a specific protocol based on repetitive transcranial magnetic stimulation (rTMS)-over the right DLPFC. Non-invasive brain stimulation is one of the few means to draw causal conclusions in human neuroscience. In this case, rTMS was used to temporarily inhibit the right DLPFC as a presumed key player in solving Stroop conflicts in one of two measurement sessions; then, effects were examined on behavioral measures as well as neurophysiological signals reflecting task-related activity in the frontal lobes and sensory cortices. The results indicate a central role of the DLPFC in the implementation of cognitive control in terms of a suppression of distracting sensory input in both the auditory cortex and visual system (FFA) in high-conflict situations. Behavioral data confirm a reduced Stroop effect following previous incongruent trials ("Gratton effect") that was only accomplished with an intact DLPFC (i.e., following placebo stimulation). Because non-invasive brain stimulation is uniquely suited to causally test neuroscientific hypotheses in humans, these data give important insights into some of the mechanisms by which the DLPFC establishes conflict resolution across different sensory modalities.

Kreativnost i izvedba Simonova zadatka

The aim of this study was to examine performance in the Simon task regarding individual differences in creative behavior measured by The Inventory of Creative Activities and Achievements (ICAA; Diedrich et al., 2018). The study included 105 students and 57 younger working-age individuals (from 19 to 36 years of age). Three-way analyses of variance were carried out on the reaction time in the Simon task given the congruence of the previous and current trials and below/above average results on creative activities and achievements scales. The reaction time in the Simon task was on average shorter in congruent than in incongruent trials (the Simon effect), as well as in the trials preceded by congruent than in those preceded by incongruent trials. The Simon effect was only present in trials preceded by a congruent trial, while reaction times in the trials preceded by incongruent trials were shorter in incongruent than in congruent trials (the Gratton effect). However, neither the Simon nor the Gratton effect were more pronounced within more or less creative participants, but the participants with an above average result on the scale of creative activities reacted on average more slowly than individuals with below the average score. The correlations between the scores on the creativity measures and the different reaction times and indices of the Simon and Gratton effect were not significant. The expected effects related to the Simon task have been obtained in this study, but further research is needed to try to replicate the findings regarding the flexibility of inhibitory control measured by performance in the Simon task and creative behavior.

Strategy or local control? Interaction of Gratton effect and proportion’s effect in the Stroop test

Models of cognitive control contain the mechanism of the general strategy of solving a task and control of specific stimuli special mechanisms. There is an ongoing discussion as to which control is responsible for the Gratton effect and the Stroop test’s proportion effect. The Gratton effect consists in decreasing the Stroop effect after an incongruent stimulus, the proportion effect is to increase interference when incongruent stimuli predominate among other types of stimuli. In this study, we set out to test whether there would be an interaction between these effects. If it is detected, we can say that both effects of study are produced by a general cognitive mechanism. Similar studies of general strategy using the Stroop task include congruent and incongruent stimuli. Congruent stimuli produce a response facilitation effect that is mixed with an interference effect, making final interpretation difficult. To avoid this, we used different proportions of incongruent and neutral stimuli. We conducted three experiments using different proportions of incongruent versus neutral stimuli (66:33/33:66 and 80:20/20:80), as well as the type of design (intragroup and intergroup plans). Only the Gratton effect was detected in the experiments performed — no proportion effect or significant interaction between the Gratton and proportion effects was found. In three experiments (N=70), only indirect evidence was found for the effect of proportion on the Gratton effect. These results are difficult to explain in terms of “strategic” interference model who explain both effects by a change in the global strategy for solving the task. Given the systematic lack of interaction between the Gratton effect and other effects in the literature, we can say that the Gratton effect is caused by a local control system, which the proportion effect influences, if at all, only slightly. The connection between the proportion effect and strategic control and the factors that mediate it are discussed.

Flexible top-down control in the interaction between working memory and perception.

Successful goal-directed behavior often requires continuous sensory processing while simultaneously maintaining task-related information in working memory (WM). Although WM and perception are known to interact, little is known about how their interactions are controlled. Here, we tested the hypothesis that WM perception interactions engage two distinct modes of control – proactive and reactive – in a manner similar to classic conflict-adaptation tasks (e.g. Stroop, flanker, and Simon). Participants performed a delayed recall-of-orientation WM task, plus a standalone visual discrimination-of-orientation task the occurred during the delay period, and with the congruity in orientation between the tasks manipulated. Proactive control was seen in the sensitivity of task performance to the previous trial's congruity (i.e. a Gratton effect). Reactive control was observed in a repulsive serial-dependence produced by incongruent discriminanda. Quantitatively, these effects were explained by parameters from a reinforcement learning-based model that tracks trial-to-trial fluctuations in control demand: reactive control by a phasic control prediction error (control PE), and proactive control by a tonic level of predicted conflict updated each trial by the control PE. Thus, WM-perception interactions may be controlled by the same mechanisms that govern conflict in other domains of cognition, such as response selection.

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.

Neural and behavioral effects of perceptual load on auditory selective attention

Healthy adults performed an auditory version of the flanker task under low versus high perceptual load while behavioral and electrophysiological measures were recorded. Participants experienced less attentional interference under low load than high load, whether analyses were performed between tasks (Garner interference; found in accuracy and RT), between stimuli (flanker congruity; found in accuracy), or between sequences (Gratton effect; found in accuracy). Analysis of event-related potentials to the distractor (flanker), which was physically identical across load conditions, revealed load modulation of tasks effects in the P1 component (peak amplitude and latency), an early perceptual component peaking approximately 75 ms after distractor onset. As in behavioral performance, ERP analyses showed that auditory attentional disruption in P1 was significantly smaller under low perceptual load. Dipole source analysis suggested activation of prefrontal inhibitory control during low load and default mode network during high load. The results are in keeping with the predictions of tectonic theory (Melara & Algom, 2003), but inconsistent with expectations derived from perceptual load theory (Lavie, 1995).

The Role of Subjective Experiences in Conflict Tasks: A Review.

Cognitive control research is concerned with the question how we install adaptive behaviour in the case of (cognitive) conflict. In this review we focus on the role that awareness of this conflict plays in our ability to exert cognitive control. We will argue that visual conflict is not the only building block of metacognitive experiences of conflict and discuss how they are related to cognitive control. So, a first aim of the current review is to understand how these different metacognitive judgements are created. To do so, we draw some remarkable parallels with research on metacognition in decision making and memory research. Next, we elaborate on the relationship between metacognition and adaptive behaviour, with a specific focus on the role of subjective experiences in the Gratton effect. The grey areas that persist in the current literature are highlighted. In addition to deciphering the mechanisms of metacognitive judgements in cognitive control, this overview also aims to further enlarge our understanding of metacognitive abilities at a more general level.

Electrophysiological and behavioral indices of cognitive conflict processing across adolescence

Cognitive control enables goal-oriented adaptation to a fast-changing environment and has a protracted development spanning into young adulthood. The neurocognitive processes underlying this development are poorly understood. In a cross-sectional sample of participants 8–19 years old (n = 108), we used blind source separation of EEG data recorded in a Flanker task to derive electrophysiological measures of attention and conflict processing, including a N2-like frontal negative component and a P3-like parietal positive component. Outside the recording session, we examined multiple behavioral measures of interference control derived from the Flanker, Stroop, and Anti-saccade tasks. We found a positive association between age and P3 amplitude, but no relationship between age and N2 amplitude. A stronger N2 was age-independently related to better performance on Stroop and Anti-saccade measures of interference control. A Gratton effect was found on the Flanker task, with slower reaction times on current congruent and better accuracy on current incongruent trials when preceded by incongruent as opposed to congruent trials. The Gratton effect on accuracy was positively associated with age. Together, the findings suggest a multifaceted developmental pattern of the neurocognitive processes involved in conflict processing across adolescence, with a more protracted development of the P3 compared to the N2.

Effects of conflict trial proportion: A comparison of the Eriksen and Simon tasks

Two experiments examined global and local behavioral adaptation effects within and across the Eriksen task, where conflict is based on stimulus letter identities, and the Simon task, where conflict is based on stimulus and response locations. Trials of the two tasks were randomly intermixed, and the list-wide proportion of congruent trials was varied in both tasks (Experiment 1) or in just one task (Experiment 2). The global adaptation effect of list-wide congruency proportion (LWPC effect) was at least as large in the Simon task as in the Eriksen task. Likewise, the local adaptation effect of previous-trial congruency (Gratton effect) was at least as large in the Simon task as in the Eriksen task. In contrast to prior studies investigating transfer across Stroop and Simon tasks, there was no dissociation between global and local adaptation effects regarding their transfer across the different conflict tasks. In fact, both local and global adaptation effects appeared largely task-specific, because there was no or only little transfer of either Gratton effects or LWPC effects from the Eriksen to the Simon task or vice versa. On the whole, the results suggest that behavioral adaptation observed in the present design does not carry over from one of these tasks to the other, suggesting no involvement of a higher-order, task-general mechanism of cognitive control.

Investigating the effects of pre-stimulus cortical oscillatory activity on behavior

Rhythmic brain activity may reflect a functional mechanism that facilitates cortical processing and dynamic interareal interactions and thereby give rise to complex behavior. Using magnetoencephalography (MEG), we investigated rhythmic brain activity in a brain-wide network and their relation to behavior, while human subjects executed a variant of the Simon task, a simple stimulus-response task with well-studied behavioral effects. We hypothesized that the faster reaction times (RT) on stimulus-response congruent versus incongruent trials are associated with oscillatory power changes, reflecting a change in local cortical activation. Additionally, we hypothesized that the faster reaction times for trials following instances with the same stimulus-response contingency (the so-called Gratton effect) is related to contingency-induced changes in the state of the network, as measured by differences in local spectral power and interareal phase coherence. This would be achieved by temporarily upregulating the connectivity strength between behaviorally relevant network nodes. We identified regions-of-interest that differed in local synchrony during the response phase of the Simon task. Within this network, spectral power in none of the nodes in either of the studied frequencies was significantly different in the pre-cue window of the subsequent trial. Nor was there a significant difference in coherence between the task-relevant nodes that could explain the superior behavioral performance after compatible consecutive trials.

Evidence for trial-by-trial dynamic adjustment of task control in unmedicated adults with OCD

According to the conflict monitoring theory, executive control requires two separable processes: conflict-monitoring and conflict-resolution. Deficits in executive control have been observed in adults with obsessive-compulsive disorder (OCD). However, it is not yet clear whether these deficits can be attributed to deficits in conflict-monitoring, in conflict-resolution, or in both. We examined this question by administrating the Simon task to 67 unmedicated adults with OCD and 67 matched controls. The interference effect (incongruent minus congruent) was used to measure conflict-resolution. Trial-by-trial dynamic adaptation (i.e., the Gratton effect), which is indicated by smaller interference effect after conflict-laden trials compared to after non-conflict-laden trials, was used to measure conflict-monitoring. A similar interference effect was found in both the OCD and HC groups with no significant between group differences. Following incongruent trials, the interference effect became smaller for the control group as expected, but was completely eliminated for the OCD group. These data add to the accumulating evidence indicating that conflict-resolution is not globally deficient in unmedicated OCD patients and provide direct evidence that conflict-monitoring is heightened in OCD patients. Our results challenge the assumption of cognitive inflexibility in OCD and highlight the importance of studying unmedicated subjects when investigating executive control.

Methamphetamine Users Show No Behavioral Deficits in Response Selection After Protracted Abstinence.

Introduction: Chronic recreational methamphetamine use causes dopaminergic neurotoxicity, which has been linked to impairments in executive functioning. Within this functional domain, response selection and the resolution of associated conflicts have repeatedly been demonstrated to be strongly modulated by dopamine. Yet, it has never been investigated whether chronic methamphetamine use leads to general impairments in response selection (i.e., irrespective of consumption-associated behavior) after substance use is discontinued.Materials and Methods: We tested n = 24 abstinent methamphetamine users (on average 2.7 years of abstinence) and n = 24 individually matched controls in a cross-sectional design with a flanker task.Results: Compared to healthy controls, former methamphetamine consumers had significantly slower reaction times, but did not show differences in the size of the flanker or Gratton effect, or post-error slowing. Complementary Bayesian analyses further substantiated this lack of effects despite prior consumption for an average of 7.2 years.Discussion: The ability to select a correct response from a subset of conflicting alternatives, as well as the selective attention required for this seem to be largely preserved in case of prolonged abstinence. Likewise, the ability to take previous contextual information into account during response selection and to process errors seem to be largely preserved as well. Complementing previously published finding of worse inhibition/interference control in abstinent consumers, our results suggest that not all executive domains are (equally) impaired by methamphetamine, possibly because different cognitive processes require different levels of dopamine activity.

Attentional Reorientation and Inhibition Adjustment in a Verbal Stroop Task: A Lifespan Approach to Interference and Sequential Congruency Effect.

Several parameters influence the interference effect elicited in a Stroop task, especially contextual information. Contextual effects in the Stroop paradigms are known as the Gratton or Sequential congruency effect (SCE). This research aims at isolating two processes contributing to the SCE in a Stroop paradigm, namely attentional reorientation from the color to the word and vice-versa, as well as inhibition (engagement/disengagement from one trial to the next one). To this end, in Study 1 subprocesses of the SCE were isolated. Specifically, attentional reorientation and inhibition were segregated by submitting young adults to a discrete verbal Stroop task including neutral trials. In Study 2, the same procedure was applied to 124 participants aged from 10 to 80 years old to analyze how interference, SCE, and the aforementioned decomposition of attention and inhibition change across the lifespan. In both studies, the Gratton effect was only partially replicated, while both attentional reorientation and inhibition effects were observed, supporting the idea that these two processes contribute to SCE on top of conflict monitoring and of other processes highlighted in different theories (contingency learning, feature integration, and repetition expectancy). Finally, the classical age-related evolution was replicated in Study 2 on raw interference scores, but no age effect was observed when processing speed was taken into account, nor on the isolated attentional reorientation and inhibition processes, which is in line with the hypothesis of stability of the inhibition processes over age.

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.

Alcohol Hangover Increases Conflict Load via Faster Processing of Subliminal Information.

The detrimental effects of acute alcohol intoxication and long-term alcohol (ab)use on cognition are well-known. Yet, only little is known about the cognitive effects of an acute alcohol hangover, even though it might affect executive functions associated with workplace performance or driving skills. Given that alcohol hangover may increase the speed of information accumulation, we assessed the behavioral effects of conflict load (induced by a subliminal prime) on cognitive control, as assessed via the Flanker effect. We employed a counter-balanced within-subject design, where n = 25 healthy young males were tested once after a sober night and once after a night of experimentally induced heavy drinking of cheap brandy/red wine (2.6375 g alcohol per estimated liter of body water within 2–3 h). Alcohol hangover neither increased the cognitive conflicts induced by consciously processed distractors alone (i.e., the Flanker effect), nor modulated conflict adaptation (i.e., the Gratton effect). Instead, hangover potentiated the detrimental effects of conflicting subliminal primes on top-down cognitive conflicts. This effect was likely due to an increase in the speed of information accumulation from visual stimuli and the resulting increase in subliminal conflict load induced by incompatible primes. We further found the size of this effect to be positively correlated with age and subjective sleepiness during the hangover state, but the hangover effect remained significant even after correcting for those covariates. We further found no correlation of the behavioral effect with the subjective overall rating of hangover symptoms or the maximal breath alcohol concentration reached during prior intoxication. Taken together, our findings suggest that alcohol hangover may affect cognitive performance due to an increase in non-conscious processing of visual distractors. While the size of this effect might increase with age and sleepiness, it is not entirely dependent on those covariates and not necessarily related to subjective ratings of general hangover symptoms/impairment.

Comparing adaptation in emotional and non-emotional conflict in patients with schizophrenia and borderline personality disorder

Research on conflict adaptation suggests that complex networks are involved in the detection and resolution of conflicts. These networks are believed to be different depending on whether the conflict occurs in emotional or non-emotional contexts. In addition, the adaptation to both types of conflict also seems to have different neural bases. The main aim of the present study was to compare conflict adaptation in two clinical groups – patients with schizophrenia (SZ) and patients with borderline personality disorder (BPD) – and a healthy control group during emotional and non-emotional versions of a facial Stroop task. We considered that the neural impairment and neuropsychological profile of these populations would be interesting to examine the above-mentioned mechanisms. Results showed that the performance was worse with incongruent compared to congruent stimuli in both task contexts. The Stroop effect was more marked in both clinical groups and greater in the SZ group. By contrast, the Gratton effect was clearly present in the SZ group, but was inverted in the BPD group mainly in the emotional task. Specifically, participants with BDP had a higher error rate in the current incongruent trial when the previous trial was incongruent in the emotional task. These results suggest that SZ and BDP groups have different patterns of conflict adaptation. Results are discussed according to the clinical characteristics and neural systems affected in each of these psychopathological disorders.

Can the post-error effect mask age-related differences in congruency conditions when education and overall accuracy are controlled for?

ObjectiveAge-related differences in stimulus–response congruency tasks have been attributed to older adults' greater difficulties in handling the irrelevant spatial-dimensional overlap between stimulus and response. However, performance on congruency tasks may also be influenced by the previous trial accuracy (i.e. post-error effect), which may affect young and older adults differently. The main objective of this study was to analyse age-related differences in the post-error effect as a function of congruency. In addition, we examined the meditational role of the Gratton effect on the age-related differences in the post-error slowing (PES) and post-error increased accuracy (PIA) as a function of congruency. MethodThe sample comprised 165 healthy adult participants with diverse educational attainment, divided into five age groups. Participants performed a spatial stimulus–response congruency task. Age-related differences in the post-error effect were analysed for each congruency condition taking into account educational attainment and overall accuracy. Statistical procedures were used to neutralize age-related processing speed effects on the PES. ResultsPES was observed across all age groups, except the Very old group (aged 85–98 years), and it was not related to congruency condition. PIA was observed across age groups in all congruency conditions and was slightly higher in incongruent trials. Evidence of simultaneous PES and PIA was found for young participants and older participants under 85 years. The Very old group did not need to significantly slow down their responses after errors to improve accuracy. No age- related difference was found in the influence of the Gratton effect on PES or PIA as a function of congruency. ConclusionsPES and PIA were observed in young adults and older adults under 85 years old. Evidence of simultaneous PES and PIA in the young and older age group (except for the Very old) indicates that the post-error effect can be interpreted in terms of recruitment of additional resources to prevent subsequent errors. Slightly higher accuracy was observed in the incongruent condition in post-error trials relative to pre-error correct trials across age groups.

Deconstructing the Gratton effect: Targeting dissociable trial sequence effects in children, pre-adolescents, and adults

The Gratton effect refers to the observation that performance on congruency tasks is often enhanced when the congruency of the current trial matches that of the previous trial. This effect has been at the center of recent debates in the literature on cognitive control as researchers have sought to identify the cognitive and neural underpinnings of the effect. Here, we use a technique known as reach tracking to demonstrate that the Gratton effect originally observed in the flanker task is not a singular effect but the result of two separate trial sequence effects that impact dissociable processes underlying cognitive control. Further, our results indicate that these dissociable processes follow divergent developmental trajectories across childhood, pre-adolescence, and adulthood. Taken together, these findings suggest that manual dynamics can be used to disentangle how key processes underlying cognitive control contribute to the response time effects observed across a wide range of cognitive tasks and age groups.

Metacognition and cognitive control: behavioural adaptation requires conflict experience.

Cognitive control allows adapting our behaviour to improve performance. A behavioural signature of cognitive control is the Gratton effect. This effect is observed in conflict tasks and indicates smaller congruency effects after incongruent trials than after congruent trials. Metacognitive experience may play a role in this effect: When participants introspect on their conflict experience, the Gratton effect follows the conflict introspection instead of the stimulus congruency. However this Gratton effect could also be triggered by the labelling that the introspective method implies and/or by a misperception of the stimulus conflict. The current study investigated whether the experiential component of the introspection is necessary to trigger cognitive control or whether labelling a trial as conflicting or not can be sufficient. In a priming task, Gratton effects following metacognitive conflict experience and conflict label were contrasted. Replicating earlier reports, results showed that the metacognitive experience of conflict can trigger a Gratton effect. However a conflict label, either generated by the participants themselves or presented to the participants via feedback was not able to induce cognitive control. Results are discussed in light of current theories of cognitive control.

Temporal Dynamics of Human Frontal and Cingulate Neural Activity During Conflict and Cognitive Control.

Cognitive control refers to the ability to produce flexible, goal-oriented behavior in the face of changing task demands and conflicting response tendencies. A classic cognitive control experiment is the Stroop-color naming task, which requires participants to name the color in which a word is written while inhibiting the tendency to read the word. By comparing stimuli with conflicting word-color associations to congruent ones, control processes over response tendencies can be isolated. We assessed the spatial specificity and temporal dynamics in the theta and gamma bands for regions engaged in detecting and resolving conflict in a cohort of 13 patients using a combination of high-resolution surface and depth recordings. We show that cognitive control manifests as a sustained increase in gamma band power, which correlates with response time. Conflict elicits a sustained gamma power increase but a transient theta power increase, specifically localized to the left cingulate sulcus and bilateral dorsolateral prefrontal cortex (DLPFC). Additionally, activity in DLPFC is affected by trial-by-trial modulation of cognitive control (the Gratton effect). Altogether, the sustained local neural activity in dorsolateral and medial regions is what determines the timing of the correct response.