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.     

Exploring emotional and cognitive conflict using speeded voluntary facial expressions

Affective conflict and control may have important parallels to cognitive conflict and control, but these processes have been difficult to quantitatively study with emotionally naturalistic laboratory paradigms. The current study examines a modification of the AX-Continuous Performance Task (AX-CPT), a well-validated probe of cognitive conflict and control, for the study of emotional conflict. In the Emotional AX-CPT, speeded emotional facial expressions measured with electromyography (EMG) were used as the primary response modality, and index of emotional conflict. Bottom-up emotional conflict occurred on trials in which precued facial expressions were incongruent with the valence of an emotionally evocative picture probe (e.g., smiling to a negative picture). A second form of top-down conflict occurred in which the facial expression and picture probe were congruent, but the opposite expression was expected based on the precue. A matched version of the task was also performed (in a separate group of participants) with affectively neutral probe stimuli. Behavioral interference was observed, in terms of response latencies and errors, on all conflict trials. However, bottom-up conflict was stronger in the emotional version of the task compared to the neutral version; top-down conflict was similar across the two versions. The results suggest that voluntary facial expressions may be more sensitive to indexing emotional than nonemotional conflict, and importantly, may provide an ecologically valid method of examining how emotional conflict may manifest in behavior and brain activity.     

Conflict-induced perceptual filtering

In a variety of conflict paradigms, target and distractor stimuli are defined in terms of perceptual features. Interference evoked by distractor stimuli tends to be reduced when the ratio of congruent to incongruent trials is decreased, suggesting conflict-induced perceptual filtering (i.e., adjusting the processing weights assigned to stimuli associated with the target and with the distractor features). In search of evidence for such a mechanism, we administered a flanker task, in which targets and distractors were defined in terms of stimulus location (Experiment 1) or color (Experiment 2). The efficiency of processing stimuli associated with target and distractor features was assessed in intermixed trials of a visual search task, in which a target had to be detected irrespective of these features. In both experiments search times were shorter for stimuli associated with the target feature than with the distractor feature of the flanker task. This effect was increased under conditions of a reduced congruent/incongruent ratio, thereby providing evidence for conflict-dependent perceptual filtering.     

Task conflict effect in task switching

A part of action preparation is deciding what the relevant task is. This task-decision process is conceptually separate from response selection. To show this, the authors manipulated task conflict in a spatial task-switching paradigm, using conflict stimuli that appeared during trials with univalent targets (affording 1 task). The conflict stimuli afforded task identity because they were used as task cues with bivalent targets (affording 2 tasks) that were intermixed with the univalent targets. Thus, for univalent targets, irrelevant stimuli either caused low task conflict or high task conflict. In three experiments, the authors found poorer performance in high task conflict trials than in low task conflict trials. Task conflict was introduced during target appearance (Experiment 1) or task preparation (Experiments 2 and 3). In the latter case, the task conflict effect decreased with increasing task preparation time showing that task preparation involves task decision.     

Cognitive control: A role for implicit learning?

We investigated the influence of implicit learning on cognitive control. In a sequential Stroop task, participants implicitly learned a sequence placed on the color of the Stroop words. In Experiment 1, Stroop conflict was lower in sequenced than in random trials (learning-improved control). However, as these results were derived from an interaction between learning and conflict, they could also be explained by improved implicit learning (difference between random and sequenced trials), under incongruent compared with congruent trials (control-improved learning). Therefore, we further unraveled the direction of the interaction in 2 additional experiments. In Experiment 2, participants who learned the color sequence were no better at resolving conflict than participants who did not undergo sequence training. This shows that implicit knowledge does not directly reduce conflict (no learning-improved control). In Experiment 3, the amount of conflict did not directly improve learning either (no control-improved learning). However, conflict had a significant impact on the expression of implicit learning, as most knowledge was expressed under the highest amount of conflict. Thus, task-optimization was accomplished by an increased reliance on implicit sequence knowledge under high conflict. These findings demonstrate that implicit learning processes can be flexibly recruited to support cognitive control functions. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

冲突观察能诱发冲突适应

重复启动效应和一致试次所占的比例都会影响冲突适应效应。采用词-色Stroop任务, 本研究在控制了重复启动效应和一致试次的比例之后, 通过三个实验共同探讨反应执行和冲突观察对冲突适应效应的影响。实验一发现当前试次的Stroop干扰效应, 但没有得到冲突适应效应; 在实验二中, 先前试次为四选一的选择反应时任务, 当前试次为词-色Stroop任务, 得到反转的冲突适应效应; 实验三和实验一程序相似, 但在先前试次上不执行反应, 得到了稳定的冲突适应效应。这些结果证明, 冲突观察能够诱发冲突适应机制, 提升当前的操作表现。     

On the bilingual advantage in conflict processing: Now you see it, now you don’t

We report two experiments exploring more in detail the bilingual advantage in conflict resolution tasks. In particular, we focus on the origin of the bilingual advantage on overall reaction times in the flanker task. Bilingual and monolingual participants were asked to perform a flanker task under different task versions. In Experiment 1, we used two low-monitoring versions where most of the trials were of just one type (either congruent or incongruent). In Experiment 2, we used two high-monitoring versions where congruent and incongruent trials were more evenly distributed. An effect of bilingualism in overall reaction times was only present in the high-monitoring condition. These results reveal that when the task at hand recruits a good deal of monitoring resources, bilinguals outperform monolinguals. This observation suggests that bilingualism may affect the monitoring processes involved in executive control.     

Signals of threat do not capture, but prioritize, attention: a conditioning approach

Research suggests that threatening information captures attention more rapidly than neutral information. However, in most studies threat stimuli differ perceptually from neutral stimuli and are instrumental to perform the task, leaving the question unanswered whether threat is sufficient to capture attention. In experiment 1, we designed a visual search task with stimuli of equal salience (colored circles) that have the potential to lead to efficient search (10 ms/item). In experiment 2, one of the colors (conditioned stimulus, CS+) was made threatening by means of fear conditioning. Participants responded to a target presented in one of the circles. Overall, the search was faster on congruent trials (where the target was presented in the CS+) than on baseline trials (where the CS + was absent). Furthermore, the search was slower on incongruent trials (where the target was presented in another color than the CS+) than on baseline trials. The search on congruent trials was affected by set size (90 ms/item), but to a lesser extent than on baseline trials (105 ms/item). We conclude that threat prioritizes, but does not capture attention.     

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.     

Effect of short and long exposure duration and dual-tasking on a global-local task

Past research has demonstrated a global advantage in responses to visually presented hierarchical stimuli such that, on incongruent trials, the global form interferes with responses to the local level [Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112, 24-38]. In Experiment 1, 32 adults performed alternating blocks of global or local identification of hierarchical letter stimuli in which the global and local letters were congruent, incongruent, or neutral, and were presented at either a short (17 ms) or long (100 ms) exposure duration. A global advantage was demonstrated at both durations. In the local-directed task, interference on incongruent, relative to neutral, trials was observed at both exposure durations, but facilitation on congruent trials, relative to neutral trials, was present only when stimuli were presented at the long exposure duration. In Experiment 2, global or local identification was performed by another group of 24 adults at either a long or short exposure duration, and also under conditions of full attention (FA) or dual-task (DT) conditions with a digit-monitoring task. Under FA, we again found significant interference at both exposure durations, but facilitation only at the long exposure duration. Under DT conditions, the pattern of facilitation and interference at the short duration remained unchanged. At the long duration, however, dual-tasking eliminated interference in the RT but not error data, while facilitation was present in both sets of data. Results are in line with a perceptual account of the global advantage, and suggest that facilitation requires consciously-mediated processes, whereas interference does not.     

Emotional attention: effects of emotion and gaze direction on overt orienting of visual attention

In the present study we considered the two factors that have been advocated for playing a role in emotional attention: perception of gaze direction and facial expression of emotions. Participants performed an oculomotor task in which they had to make a saccade towards one of the two lateral targets, depending on the colour of the fixation dot which appeared at the centre of the computer screen. At different time intervals (stimulus onset asynchronies, SOAs: 50,100,150 ms) following the onset of the dot, a picture of a human face (gazing either to the right or to the left) was presented at the centre of the screen. The gaze direction of the face could be congruent or incongruent with respect to the location of the target, and the expression could be neutral or angry. In Experiment 1 the facial expressions were presented randomly in a single block, whereas in Experiment 2 they were shown in separate blocks. Latencies for correct saccades and percentage of errors (saccade direction errors) were considered in the analyses. Results showed that incongruent trials determined a significantly higher percentage of saccade direction errors with respect to congruent trials, thus confirming that gaze direction, even when task-irrelevant, interferes with the accuracy of the observer’s oculomotor behaviour. The angry expression was found to hold attention for a longer time with respect to the neutral one, producing delayed saccade latencies. This was particularly evident at 100 ms SOA and for incongruent trials. Emotional faces may then exert a modulatory effect on overt attention mechanisms.     

Losing control in front of a fearful face: The effect of emotional information on cognitive control

How is our cognitive control system modulated by emotional information, especially fearful stimuli? An intuitive hypothesis is that fearful stimuli would enhance cognitive control so that people could switch from the ongoing task to emergent events more quickly to secure themselves. To test this hypothesis, we investigated the influence of emotional information on the shift function of cognitive control by using the task-cueing procedure, in which face images were presented as cues. With the gender of faces indicating which task to do, we manipulated the emotional valence of faces (neutral vs. fearful), finding that the switch costs were larger in the trials containing fearful cues than in the trials containing neutral cues (Experiment 1). This effect was not caused by enlarging task-set interference (Experiment 2), nor by slowing down cue encoding (Experiment 3). Contrary to the intuitive hypothesis, our results suggested that the endogenous task-set reconfiguration process was impaired when fearful faces were presented. We speculated that the benefit of decreasing cognitive flexibility in face of fearful stimuli is to speed up response in a dangerous environment, and this accelerating response is achieved by suppressing the goal-directed system to permit the fast, automatic stimulus-driven system to govern behaviours.     

Losing control in front of a fearful face: the effect of emotional information on cognitive control

How is our cognitive control system modulated by emotional information, especially fearful stimuli? An intuitive hypothesis is that fearful stimuli would enhance cognitive control so that people could switch from the ongoing task to emergent events more quickly to secure themselves. To test this hypothesis, we investigated the influence of emotional information on the shift function of cognitive control by using the task-cueing procedure, in which face images were presented as cues. With the gender of faces indicating which task to do, we manipulated the emotional valence of faces (neutral vs. fearful), finding that the switch costs were larger in the trials containing fearful cues than in the trials containing neutral cues (Experiment 1). This effect was not caused by enlarging task-set interference (Experiment 2), nor by slowing down cue encoding (Experiment 3). Contrary to the intuitive hypothesis, our results suggested that the endogenous task-set reconfiguration process was impaired when fearful faces were presented. We speculated that the benefit of decreasing cognitive flexibility in face of fearful stimuli is to speed up response in a dangerous environment, and this accelerating response is achieved by suppressing the goal-directed system to permit the fast, automatic stimulus-driven system to govern behaviours.     

无意识信息的刺激表征及其时间特性

无意识信息是否存在刺激表征有待解决。实验采用字母Flanker任务, 通过目标和flanker在刺激水平和反应水平上的冲突效应, 重点考察阈下flanker在刺激水平的表征。在相同的实验设计下, flanker可觉察时(实验1A), 观察到经典的刺激冲突效应和反应冲突效应; 而flanker无意识时(实验1B), 重复了反应冲突效应, 却观察到刺激冲突效应发生反转, 提示了无意识信息的反应加工及刺激加工。实验2采用符号材料促使刺激−反应的自动联结, 减少刺激−反应规则的难度, 结果重复了实验1B的发现--无意识信息引起反转的刺激冲突。刺激冲突下反转效应的一致结果表明无意识信息的刺激表征影响了认知加工。实验3考察这种影响在时间进程上的特点。无意识刺激表征的影响随反应时变化：在快速反应中观察到刺激冲突效应, 之后该效应发生反转且反转量随反应时增加而增大。相反, 无意识反应表征的影响在不同反应时下保持稳定。以上结果提供了无意识信息存在刺激表征的行为学证据并揭示了其时间特性, 提供了无意识领域中不一致研究结果的整合思路。     

Congruency sequence effect in cross-task context: Evidence for dimension-specific modulation

The congruency sequence effect refers to a reduced congruency effect after incongruent trials relative to congruent trials. This modulation is thought to be, at least in part, due to the control mechanisms resolving conflict. The present study examined the nature of the control mechanisms by having participants perform two different tasks in an alternating way. When participants performed horizontal and vertical Simon tasks in Experiment 1A, and horizontal and vertical spatial Stroop task in Experiment 1B, no congruency sequence effect was obtained between the task congruencies. When the Simon task and spatial Stroop task were performed with different response sets in Experiment 2, no congruency sequence effect was obtained. However, in Experiment 3, in which the participants performed the horizontal Simon and spatial Stroop tasks with an identical response set, a significant congruency sequence effect was obtained between the task congruencies. In Experiment 4, no congruency sequence effect was obtained when participants performed two tasks having different task-irrelevant dimensions with the identical response set. The findings suggest inhibitory processing between the task-irrelevant dimension and response mode after conflict.     

Sequential congruency effects: disentangling priming and conflict adaptation

Responding to the color of a word is slower and less accurate if the word refers to a different color (incongruent condition) than if it refers to the same color (congruent condition). This phenomenon, known as the Stroop effect, is modulated by sequential effects: it is bigger when the current trial is preceded by a congruent condition than by an incongruent one in the previous trial. Whether this phenomenon is due to priming mechanisms or to cognitive control is still debated. To disentangle the contribution of priming with respect to conflict adaptation mechanisms in determining sequential effects, two experiments were designed here with a four-alternative forced choice (4-AFC) Stroop task: in the first one only trials with complete alternations of features were used, while in the second experiment all possible types of repetitions were presented. Both response times (RTs) and errors were evaluated. Conflict adaptation effects on RTs were limited to congruent trials and were exclusively due to priming: they disappeared in the priming-free experiment and, in the second experiment, they occurred in sequences with feature repetitions but not in complete alternation sequences. Error results, instead, support the presence of conflict adaptation effects in incongruent trials. In priming-free sequences (Experiment 1 and complete alternation sequences of Experiment 2) with incongruent previous trials there was no error Stroop effect, while this effect was significant with congruent previous trials. These results indicate that cognitive control may modulate performance above and beyond priming effects.     

Preattentive processing of audio-visual emotional signals

Previous research has shown that redundant information in faces and voices leads to faster emotional categorization compared to incongruent emotional information even when attending to only one modality. The aim of the present study was to test whether these crossmodal effects are predominantly due to a response conflict rather than interference at earlier, e.g. perceptual processing stages. In Experiment 1, participants had to categorize the valence and rate the intensity of happy, sad, angry and neutral unimodal or bimodal face–voice stimuli. They were asked to rate either the facial or vocal expression and ignore the emotion expressed in the other modality. Participants responded faster and more precisely to emotionally congruent compared to incongruent face–voice pairs in both the Attend Face and in the Attend Voice condition. Moreover, when attending to faces, emotionally congruent bimodal stimuli were more efficiently processed than unimodal visual stimuli. To study the role of a possible response conflict, Experiment 2 used a modified paradigm in which emotional and response conflicts were disentangled. Incongruency effects were significant even in the absence of response conflicts. The results suggest that emotional signals available through different sensory channels are automatically combined prior to response selection.     

Time counts: Bidirectional interaction between time and numbers in human adults

Number is known for influencing time processing, but to what extent time influences number in human adults is unclear. We investigated possible bidirectional interactions (number on time and time on number) using a novel Stroop-like task; participants compared numbers or temporal durations in congruent (larger number presented for longer duration) or incongruent conditions (smaller number presented for longer duration). Time and number tasks were presented in different blocks (Experiment 1) or within the same block of trials with task instructions provided at the offset of the stimuli (Experiment 2). Analyses of response times (RTs) and their distribution revealed that number affected time from early RTs, and time affected number at late RTs – an asymmetry observed only when time and number tasks were presented in separate blocks. Thus, carefully chosen tasks and appropriate data analysis can reveal bidirectionality between time and number, consistent with shared magnitude or decision mechanisms.     

Generalizing attentional control across dimensions and tasks: Evidence from transfer of proportion-congruent effects

Three experiments investigated transfer of list-wide proportion congruent (LWPC) effects from a set of congruent and incongruent items with different frequency (inducer task) to a set of congruent and incongruent items with equal frequency (diagnostic task). Experiments 1 and 2 mixed items from horizontal and vertical Simon tasks. Tasks always involved different stimuli that varied on the same dimension (colour) in Experiment 1 and on different dimensions (colour, shape) in Experiment 2. Experiment 3 mixed trials from a manual Simon task with trials from a vocal Stroop task, with colour being the relevant stimulus in both tasks. There were two major results. First, we observed transfer of LWPC effects in Experiments 1 and 3, when tasks shared the relevant dimension, but not in Experiment 2. Second, sequential modulations of congruency effects transferred in Experiment 1 only. Hence, the different transfer patterns suggest that LWPC effects and sequential modulations arise from different mechanisms. Moreover, the observation of transfer supports an account of LWPC effects in terms of list-wide cognitive control, while being at odds with accounts in terms of stimulus–response (contingency) learning and item-specific control.