Multiple levels of control in the Stroop task

Multiple levels of control may be used in service of reducing Stroop interference. One is list-wide, whereby interference is reduced strategically in lists that include disproportionately more incongruent trials. A second, item-specific control is observed when proportion congruence is manipulated at the level of items. Item-specific control reduces interference for mostly incongruent relative to mostly congruent items. First, we show that item-specific control may drive both list-wide and item-specific proportion congruence effects (Experiment 1). We then show that item-specific control affects Stroop interference similarly when a single feature (a word) as opposed to a feature combination (a word 1 font type) signals proportion congruence (Experiment 2). Although this suggests that font type offers little advantage for controlling Stroop interference beyond the word, a novel, font-specific proportion congruence effect is observed in Experiment 3, indicating that font type can be used to control interference. These findings support the idea that multiple levels of control are used in reducing Stroop interference.     

Impact of a brief auditory attention training on a modified colour-word Stroop task in a high anxiety and worry sample

Poor attentional control leads to attentional biases that are implicated in psychological distress. Attention Training Technique (ATT) is an auditory intervention designed to strengthen attentional control. Research indicates that ATT alleviates anxiety and depressive symptoms. This study is a randomised control trial with repeated measures that tested if a lab-based, single-exposure of ATT strengthened attentional control. Forty-six nonclinical, high anxiety/worry participants received either ATT or a sham control intervention. Attentional control was assessed using the standard and a modified version of the colour-word Stroop task. The modified version incorporated tactile interference to increase perceptual load. A series of mixed effects models, simple contrasts, and z-tests were used to evaluate if cross-modal interference worsened, and whether ATT was beneficial to, attentional control. Tactile interference increased reaction times but, when Stroop interference was controlled for, this was only true on incongruent trials. The impact of ATT was greatest under high perceptual load.     

Attentional control adjustments in Eriksen and Stroop task performance can be independent of response conflict

In the Eriksen flanker and colour-word Stroop tasks, the response time (RT) difference between incongruent and congruent trials is smaller following incongruent trials than following congruent trials: the “Gratton effect” (Gratton, Coles, & Donchin, 1992). According to the prevailing conflict-monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), the Gratton effect reflects attentional control adjustment following response conflict on incongruent trials. However, because previous studies compared incongruent and congruent trials, it remains unclear to what extent the Gratton effect is driven by incongruent rather than congruent trials. To resolve this issue, we included neutral trials in addition to incongruent and congruent trials in the Eriksen (Experiment 1) and Stroop (Experiment 2) tasks. Participants responded manually and vocally in both tasks. Moreover, we assessed responding to Stroop stimuli that were preceded by neutral cues or by incongruent- or congruent-predicting cues (Experiment 3). In all three experiments, the RT difference between incongruent and congruent trials was larger for postcongruent trials than for postincongruent and postneutral trials. These findings suggest that control adjustments can be independent of response conflict, challenging conflict-monitoring theory.     

Attentional control adjustments in Eriksen and Stroop task performance can be independent of response conflict

In the Eriksen flanker and colour-word Stroop tasks, the response time (RT) difference between incongruent and congruent trials is smaller following incongruent trials than following congruent trials: the "Gratton effect" (Gratton, Coles, & Donchin, 1992). According to the prevailing conflict-monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), the Gratton effect reflects attentional control adjustment following response conflict on incongruent trials. However, because previous studies compared incongruent and congruent trials, it remains unclear to what extent the Gratton effect is driven by incongruent rather than congruent trials. To resolve this issue, we included neutral trials in addition to incongruent and congruent trials in the Eriksen (Experiment 1) and Stroop (Experiment 2) tasks. Participants responded manually and vocally in both tasks. Moreover, we assessed responding to Stroop stimuli that were preceded by neutral cues or by incongruent- or congruent-predicting cues (Experiment 3). In all three experiments, the RT difference between incongruent and congruent trials was larger for postcongruent trials than for postincongruent and postneutral trials. These findings suggest that control adjustments can be independent of response conflict, challenging conflict-monitoring theory.     

Sustained vs. transient cognitive control: Evidence of a behavioral dissociation

This study assessed whether two well known effects associated with cognitive control, conflict adaptation (the Gratton effect) and conflict context (proportion congruent effects), reflect a single common or separate control systems. To test this we examined if these two effects generalized from one kind of conflict to another by using a combined-conflict paradigm (involving the Simon and Spatial Stroop tasks) and manipulating the proportion of congruent to incongruent trials for one conflict (Simon) but not the other (Spatial Stroop). We found that conflict adaptation effects did not generalize, but the effect of conflict context did. This contrasting pattern of results strongly suggests the existence of two separate attentional control systems, one transient and responsible of online regulation of performance (conflict adaptation), the other sustained and responsible for conflict context effects.     

Age-related differences in the involvement of the prefrontal cortex in attentional control

We investigated the relative involvement of cortical regions supporting attentional control in older and younger adults during performance on a modified version of the Stroop task. Participants were exposed to two different types of incongruent trials. One of these, an incongruent-ineligible condition, produces conflict at the non-response level, while the second, an incongruent-eligible condition, produces conflict at both non-response and response levels of information processing. Greater attentional control is needed to perform the incongruent-eligible condition compared to other conditions. We examined the cortical recruitment associated with this task in an event-related functional magnetic resonance imaging paradigm in 25 older and 25 younger adults. Our results indicated that while younger adults demonstrated an increase in the activation of cortical regions responsible for maintaining attentional control in response to increased levels of conflict, such sensitivity and flexibility of the cortical regions to increased attentional control demands was absent in older adults. These results suggest a limitation in older adults’ capabilities for flexibly recruiting the attentional network in response to increasing attentional demands.     

Context-specific control and context selection in conflict tasks

This study investigated whether participants prefer contexts with relatively little cognitive conflict and whether this preference is related to context-specific control. A conflict selection task was administered in which participants had to choose between two categories that contained different levels of conflict. One category was associated with 80% congruent Stroop trials and 20% incongruent Stroop trials, while the other category was associated with only 20% congruent Stroop trials and 80% incongruent Stroop trials. As predicted, participants selected the low-conflict category more frequently, indicating that participants avoid contexts with high-conflict likelihood. Furthermore, we predicted a correlation between this preference for the low-conflict category and the control implementation associated with the categories (i.e., context-specific proportion congruency effect, CSPC effect). Results however did not show such a correlation, thereby failing to support a relationship between context control and context selection.     

RETRACTED ARTICLE: Losing control: Mostly incongruent lists postpone,but do not eliminate,the Stroop effect

Identifying the color (e.g., red) of a color word that is incongruent (e.g., “BLUE”) can be remarkably difficult. The Stroop effect is a measure of the interference between activity from word and color pathways. The efficacy of these pathways is thought to be highly contingent on the frequency of incongruent trials within a block. A block of trials with mostly incongruent (MI) trials typically results in a smaller Stroop effect than a block with mostly congruent (MC) trials. This reduction of the Stroop effect has been largely attributed to the strategic list-wide control of the word pathway. Here, the time course of the Stroop effect was explored using speed-accuracy tradeoff functions (SATfs) in tasks with 50 % congruent, MC, and MI trials. In the MC and 50 % congruent condition, color-word congruency affected the rate parameter of the SATf. In the MI condition, however, congruency affected the asymptote. This evidence is consistent with the idea that the strategic control of the word pathway is an effortful, temporary phenomenon, prone to buckle if responding is held in check.     

Top-down and bottom-up sequential modulations of congruency effects

Several studies have demonstrated reduced congruency effects after incongruent trials. The conflict monitoring hypothesis (Botvinick, Braver, Barch, Carter, & Cohen, 2001) assumes that this sequential modulation is based on top-down cognitive control and suggests that more control is engaged after the detection of conflict. An alternative account is based on repetition effects of stimulus and response features and can be considered bottom up. This study investigates both modulatory sources. In a Stroop task with two response-stimulus intervals (RSIs), we demonstrate that top-down modulation does not occur with a very short RSI, suggesting that it takes some time before the system can be reconfigured. Bottom-up modulation is observed for both RSIs. This finding demonstrates that two different sources simultaneously reduce congruency effects after incongruent trials.     

Attentional control in the aging brain: insights from an fMRI study of the stroop task

Several recent studies of aging and cognition have attributed decreases in the efficiency of working memory processes to possible declines in attentional control, the mechanism(s) by which the brain attempts to limit its processing to that of task-relevant information. Here we used fMRI measures of neural activity during performance of the color-word Stroop task to compare the neural substrates of attentional control in younger (ages: 21-27 years old) and older participants (ages: 60-75 years old) during conditions of both increased competition (incongruent and congruent neutral) and increased conflict (incongruent and congruent neutral). We found evidence of age-related decreases in the responsiveness of structures thought to support attentional control (e.g., dorsolateral prefrontal and parietal cortices), suggesting possible impairments in the implementation of attentional control in older participants. Consistent with this notion, older participants exhibited more extensive activation of ventral visual processing regions (i.e., temporal cortex) and anterior inferior prefrontal cortices, reflecting a decreased ability to inhibit the processing of task-irrelevant information. Also, the anterior cingulate cortex, a region involved in evaluatory processes at the level of response (e.g., detecting potential for error), showed age-related increases in its sensitivity to the presence of competing color information. These findings are discussed in terms of newly emerging models of attentional control in the human brain.     

音乐训练与抑制控制的关系：来自ERPs的证据

抑制控制是人类非常重要的认知功能之一, 它对个体适应环境具有重要的意义。本研究将抑制控制细分为反应抑制和冲突控制, 采用Go/No-go和Stroop任务从行为和脑电层面, 考察了音乐训练与抑制控制能力的关系及其认知神经机制。结果发现：在行为指标上, 音乐训练组比控制组的Stroop干扰效应更小, 但两组被试在Go/No-go任务表现上没有差异。在脑电指标上, 在Go/No-go任务中音乐训练组的N2差异波和P3差异波波幅(No-go减Go条件)显著大于控制组, 在Stroop任务中音乐训练组的N450差异波波幅(不一致减一致条件)也显著大于控制组, 但两组被试的SP差异波波幅(不一致减一致条件)无显著差异。结果表明：音乐训练组被试在反应抑制任务中可能具有更强的冲突监控和运动抑制能力, 在冲突控制任务中也具有更强的冲突监控能力。本研究从电生理的层面反映了音乐训练与抑制控制能力的提升具有一定的关联。     

The influence of attentional control on stimulus processing is category specific in Stroop tasks

It is still unclear how attentional control influences stimulus processing. We investigated this issue in four Stroop task experiments utilizing a pretest–training–posttest design. Subjects were given extensive training on the Stroop task using typical incongruent Stroop trials. The rates of color naming and word reading, which reflect the efficiency of stimulus processing, were assessed in pretest and posttest. The difference in rates between posttests and pretests reflects the influence of attentional control, acquired during the training phase, on stimulus processing. In Experiment 1, members of color category were used in the training phase; in Experiment 2, members of color category were used, but not in the training phase; in Experiment 3, they were neither in the color category nor were they used in the training. The results consistently showed that the suppression of word reading and the enhancement of color naming were developed in the training phases and they were not due to general training of color-naming task without conflict but to color-naming training with Stroop conflict (Experiment 4). More importantly, both suppression and enhancement affected the members of color category regardless of whether they were trained or not. The present findings suggest that the influence of attentional control on stimulus processing is category specific. We discuss the implications of the present results in terms of existing research on the locus of attentional control in Stroop tasks.     

冲突控制是领域一般性的还是领域特殊性的?

本研究采用整合交叉范式整合了Stroop任务和Simon任务,在双重认知控制的框架下探讨冲突控制是领域一般性的还是领域特殊性的问题。结果发现:序列一致性效应只出现在任务内,不出现于任务间,显示对冲突的反应性控制具有领域特殊性;比例一致性效应不仅出现在同种任务中,而且扩展到不同任务中,显示对冲突的主动性控制具有领域一般性。本研究结果对于理解认知控制的本质和机制具有重要意义。     

Interdimensional interference in the Stroop effect: uncovering the cognitive and neural anatomy of attention

In the classic Stroop effect, naming the color of an incompatible color word (e.g. the word RED printed in green ink; say, 'green') is much slower and more error-prone than is naming the color of a control item (e.g. XXX or CAT printed in green; say 'green'). This seemingly simple interference phenomenon has long provided a fertile testing ground for theories of the cognitive and neural components of selective attention. We present a sketch of the behavioral phenomenon, focusing on the idea that the relative automaticity of the two dimensions determines the direction and the degree of interdimensional interference between them. We then present an outline of current parallel processing explanations that instantiate this automaticity account, and we show how existing interference data are captured by such models. We also consider how Stroop facilitation (faster response of 'red' to RED printed in red) can be understood. Along the way, we describe research on two tasks that have emerged from the basic Stroop phenomenon - negative priming and the emotional Stroop task. Finally, we provide a survey of brain imaging research, highlighting the possible roles of the anterior cingulate in maintaining attentional set and in processing conflict or competition situations.     

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.     

Age-related differences in the involvement of the prefrontal cortex in attentional control

We investigated the relative involvement of cortical regions supporting attentional control in older and younger adults during performance on a modified version of the Stroop task. Participants were exposed to two different types of incongruent trials. One of these, an incongruent-ineligible condition, produces conflict at the non-response level, while the second, an incongruent-eligible condition, produces conflict at both non-response and response levels of information processing. Greater attentional control is needed to perform the incongruent-eligible condition compared to other conditions. We examined the cortical recruitment associated with this task in an event-related functional magnetic resonance imaging paradigm in 25 older and 25 younger adults. Our results indicated that while younger adults demonstrated an increase in the activation of cortical regions responsible for maintaining attentional control in response to increased levels of conflict, such sensitivity and flexibility of the cortical regions to increased attentional control demands was absent in older adults. These results suggest a limitation in older adults’ capabilities for flexibly recruiting the attentional network in response to increasing attentional demands.     

Ageing and bilingualism: absence of a "bilingual advantage" in stroop interference in a nonimmigrant sample

Previous research has found an advantage for bilinguals relative to monolinguals on tasks of attentional control. This advantage has been found to be larger in older adults than in young adults, suggesting that bilingualism provides a buffer against age-related declines in executive functioning. Using a computerized Stroop task in a nonimmigrant sample of young and older monolinguals and bilinguals, the current investigation tried to replicate previous findings of a bilingual advantage. A bilingual advantage would have been demonstrated by smaller Stroop interference (i.e., smaller increases in response time for incongruent than for neutral trials) for bilinguals than for monolinguals. The results showed that bilingual young adults showed a general speed advantage relative to their monolingual counterparts, but this was not associated with smaller Stroop interference. Older adults showed no effect of bilingualism. Thus, the present investigation does not find evidence of a bilingual advantage in young or older adults and suggests limits to the robustness and/or specificity of previous findings.     

冲突水平的变化诱发冲突适应

冲突适应是重要的认知控制现象, 反映了认知控制的动态过程。然而, 目前为止对于冲突水平上的差异能否诱发冲突适应尚不清楚。本研究采用字母Flanker的变式, 通过改变目标-分心物的一致性操纵冲突水平, 探究冲突水平的变化对认知控制调整的影响。结果发现被试的反应时间随冲突水平的提高而增加; 而且先前试次的一致性影响当前试次的干扰效应, 无冲突和低冲突、无冲突和高冲突、低冲突和高冲突条件之间均出现了典型的冲突适应。本研究结果表明, 除了冲突的有无, 冲突水平的变化也能诱发冲突适应, 支持更大的冲突驱动更强的认知控制, 而且冲突诱发的认知控制的功能可能通过注意聚焦实现。这一发现为冲突监测理论的注意调节机制提供了直接的支持证据, 对于促进冲突适应的相关研究具有重要意义。     

Proactive and reactive control depends on emotional valence: a Stroop study with emotional expressions and words

We examined proactive and reactive control effects in the context of task-relevant happy, sad, and angry facial expressions on a face-word Stroop task. Participants identified the emotion expressed by a face that contained a congruent or incongruent emotional word (happy/sad/angry). Proactive control effects were measured in terms of the reduction in Stroop interference (difference between incongruent and congruent trials) as a function of previous trial emotion and previous trial congruence. Reactive control effects were measured in terms of the reduction in Stroop interference as a function of current trial emotion and previous trial congruence. Previous trial negative emotions exert greater influence on proactive control than the positive emotion. Sad faces in the previous trial resulted in greater reduction in the Stroop interference for happy faces in the current trial. However, current trial angry faces showed stronger adaptation effects compared to happy faces. Thus, both proactive and reactive control mechanisms are dependent on emotional valence of task-relevant stimuli.     

Motivational and cognitive determinants of control during conflict processing

Previous studies suggest that both reward anticipation and expected or experienced conflicts activate cognitive control. The present study investigated how these factors interact during conflict processing. In two experiments, participants performed a variant of the Stroop task, receiving performance-dependent monetary rewards in some blocks. In addition, we manipulated the level of conflict-triggered reactive and expectancy-driven proactive control: In Experiment 1, we compared the Stroop effect after previously congruent and incongruent trials to examine the conflict adaptation effect (reactive control). We found that the level of motivation did not interact with conflict adaptation. In Experiment 2, we varied the proportion of congruent and incongruent trials to manipulate conflict expectancy (proactive control). The data suggest the effects of motivation to be less pronounced under conditions of high conflict expectancy. We conclude that the interaction of motivation with cognitive determinants of control depends on whether these activate proactive or reactive control processes.