无意识冲突的发生机制：基于Stroop范式的探讨

无意识信息对人们的行为有着十分重要的影响,它不仅能触发相对低级的认知功能而且也能触发冲突控制等相对高级的认知功能。尽管已有研究从行为和认知神经研究两个方面强有力地证实了无意识冲突的存在,但对无意识冲突是源自中枢加工产生的语义冲突还是晚期动作选择中产生的反应冲突存在激烈的争议。本研究采用分离语义冲突和反应冲突的实验逻辑在Stroop掩蔽启动任务中探讨了无意识冲突的机制。结果发现,无意识Stroop效应中既包含语义冲突又包含反应冲突。这说明无意识冲突可能由语义冲突和反应冲突共同构成。实验结果也进一步支持了无意识刺激可以加工到语义水平的观点。     

色-词Stroop任务中的冲突类型述评

在认知控制领域中, 色-词Stroop任务常被用于研究冲突加工的内在机制。本文首先简述色-词Stroop任务中的刺激冲突和反应冲突及研究这两类冲突常用的实验范式。然后介绍这两类冲突的神经动力学特征：事件相关电位研究显示, N450的波幅调整反映了大脑对冲突的监测, 持续电位(sustained potential, SP)的波幅调整反映了大脑对反应冲突的解决; 核磁共振成像研究显示, 前扣带回、背外侧前额叶分别在反应冲突的监测、认知控制的执行上扮演着重要的角色。文章最后针对目前研究范式存在的问题提出了改进方法和认知神经研究的新方向。     

The influence of mere social presence on Stroop interference: New evidence from the semantically-based Stroop task

Several studies have shown that mere social presence reduces Stroop interference but processes underlying such effect are still poorly understood. Given that the standard Stroop task used in those studies confounds semantic and response competition, it remains unclear whether Stroop words are processed normally (Sharma, Booth, Brown, & Huguet, 2010) or whether the processing of their semantic representations is altered (Huguet, Galvaing, Monteil, & Dumas, 1999, Exp. 1). The direct evidence from the semantically-based Stroop task (i.e., a task that is free of response competition and thus isolates the semantic component of the Stroop interference, Neely & Kahan, 2001) provided in this paper attests normal semantic processing. Such result refutes the idea that semantic activation can be prevented or controlled by social presence and thus adds to the growing body of evidence showing that semantic activation is indeed automatic. Also importantly, this paper offers an alternative explanation of past findings, which holds that social presence simply reduces the response competition that occurs in the standard Stroop task and sheds some light on the processes that underlie social-facilitating effects of mere presence in the Stroop task.     

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。     

Conflict adaptation is reflected by response interference

The conflict monitoring theory suggests that the occurrence of conflict in previous trials leads to a reduction in interference in current trials through conflict adaption. The present study included two experiments that used a colour-based flanker task and a Stroop task in combination with a 2:1 stimulus-to-response mapping manipulation and a crossing of transition types (Previous trial type×Current trial type) with stimuli to investigate conflict adaption in relation to stimulus and response interference. The results demonstrate that response interference, but not stimulus interference, was reduced following both stimuli and response conflicts in previous trials. In contrast to some recent evidence, we conclude that conflict adaptation is limited to response interference.     

Differential effects of viewing positions on standard versus semantic Stroop interference

From their finding that the substantial magnitude of the Stroop interference that occurs when a participant’s initial fixation is directed at the optimal viewing position is eliminated when the initial fixation is directed at the end of a word, Perret and Ducrot (2010) concluded that initial fixation at the latter position likely prevents reading. In the present study, we further examined this interpretation. To this end, the two conflict dimensions (semantic vs. response) that were confounded in the original work were separated within a semantically based Stroop paradigm (Neely & Kahan, 2001) that was administered with vocal (instead of manual) responses. In line with past findings showing greater interference in the vocal task, the reported results indicated that standard Stroop interference was reduced, but not eliminated, thus making the initial interpretation in terms of reading suppression unlikely. This conclusion is further strengthened by the presence of isolated semantic interference, the magnitude of which remained significant and was unaffected by viewing position. In sum, these results show that initial fixation of the end of a word simply reduces (nonsemantic) response competition.     

Preparation time modulates pro-active control and enhances task conflict in task switching

Performance in the Stroop task reflects two conflicts—informational (between the incongruent word and ink color) and task (between relevant color naming and irrelevant word reading). Neuroimaging findings support the existence of task conflict in congruent trials. A behavioral indication for task conflict—Stroop reverse facilitation—was found in previous studies under low task-control conditions. Task switching also causes reduction in task control because the task set frequently changes. We hypothesized that it would be harder to efficiently manage task conflicts in switching situations and, specifically, as cue–target interval (CTI) decreases. This suggestion was examined in two experiments using a combined Stroop task-switching design. We found a large interference effect and reverse facilitation that decreased with elongation of CTI. Results imply that task switching reduces pro-active task control and thereby enhances the informational and the task conflicts. This calls for a revision of recent control models to include task conflict.     

冲突适应效应是领域特定的

本研究采用整合的交叉任务范式,通过任务类型的操纵,对冲突适应效应是领域一般的还是领域特定的问题进行了探讨。结果发现当时,在刺激-反应集为4的字母flanker+Simon的整合交叉任务中和刺激-反应集为4的Stroop+Simon的整合交叉任务中,冲突适应效应都是仅存在于任务内,不存在于任务间。说明在控制了重复启动效应且排除了任务之间维度重叠的影响后,两种类型的整合交叉任务都只在任务内观察到冲突适应效应。这表明在控制特征整合的影响后,冲突适应效应是领域特定的,同时说明冲突监测系统不仅是对冲突进行监测,也对冲突的来源进行识别。     

特质自我控制个体在多源干扰任务下的认知神经机制

本研究采用事件相关电位技术(ERPs)结合多源干扰任务(MSIT)范式来探讨特质自我控制个体的认知神经机制。考察了高、低自我控制者各26名在MSIT任务上的差异。结果：高自我控制者的反应时显著长于低自我控制者。在MSIT冲突条件下,高自我控制者的N2和P3(LPC)波幅比无冲突条件更大。结论：高自我控制者较低自我控制者处理冲突干扰更慢,需要的注意资源较多,激活前额叶中部脑区。     

A developmental study of the auditory Stroop effect

A pediatric auditory version of the Stroop procedure was developed and administered to 48 normal children from 3 to 6 years of age. Our purpose was to define the developmental course characterizing interaction between auditory and semantic speech dimensions in young children. The procedure was a reaction time (RT) task that required children to respond as quickly and as accurately as possible to words spoken by a male or a female voice. Children were instructed to ignore what was said and to push the "Mommy" button if Mommy was talking or the "Daddy" button if Daddy was talking. Performance was obtained for words with neutral, congruent, and conflicting semantic content. Preschool children manifested processing dependencies that were similar to those observed in adults on the visual Stroop procedure. Conflict between semantic and auditory dimensions significantly increased RT and congruence between the two dimensions significantly decreased RT relative to the neutral condition. The pattern of results indicated that the meaning of words was processed automatically in the normal children. The magnitude of the Stroop effect reflected developmental change with increasing age.     

Components of Stroop-like interference in picture naming

The semantic interference effect observed in Stroop tasks and picture-word interference tasks might be due to the previous confounding of semantic similarity with task relevance (in the Stroop task) and with perceptual similarity (in the picture-word interference task). A picture-word variant of the Stroop task was devised in which the factors of task relevance and perceptual similarity were controlled. The distractor conditions allowed for the examination of four types of context effects. The results show that the overall Stroop-like interference effect can be decomposed into interference effects due to (1) a semantic relation between distractor and target, (2) the semantic relevance of the distractor word in the task at hand, (3) the presence of the distractor word in the response set, and (4) the mere presence of a word. Implications of these findings for the locus or loci of Stroop and picture-word interference effects are discussed. It is concluded that distractor words in Stroop-like naming tasks interfere mainly in the process of name retrieval.     

Interference suppression vs. response inhibition: An explanation for the absence of a bilingual advantage in preschoolers’ Stroop task performance

The well-documented advantage that bilingual speakers demonstrate across the lifespan on measures of controlled attention is not observed in preschoolers’ performance on Stroop task variations. We examined the role of task demands in explaining this discrepancy. Whereas the Color/Word Stroop used with adult participants requires interference suppression, the Stroop task typically used with preschoolers requires only response inhibition. We developed an age-appropriate conflict task that measures interference suppression. Fifty-one preschool children (26 bilinguals) completed this new Bivalent Shape Task and the Day/Night task used in previous research. Bilingual in comparison to monolingual children performed better on incongruent trials of the Bivalent Shape Task, but did not differ on other measures. The results indicate that the discrepancy between preschoolers and older individuals in performance on Stroop task adaptations results from characteristics of the task rather than developmental differences. Further, the findings provide additional support for the importance of interference suppression as a mechanism underlying the bilingual advantage.     

The effects of amount of information in the Stroop color word test

The processing time of the relevant (color) and irrelevant (word) stimulus dimensions in a Stroop color word test were each varied by manipulating the amount of information in the color and word sets from which the stimuli were obtained. Interference in the Stroop task was found to increase with increases in relevant and irrelevant stimulus information. It was concluded that the findings of increased interference with increases in both word and color processing time supported a perceptual conflict interpretation of Stroop task interference.     

选择损耗自我控制资源:取舍效应还是信息加工难度效应?

研究以自我控制的资源模型为理论框架,从选择难度特征的视角出发,通过两项实验考察选择损耗自我控制资源的成因。结果发现,高取舍冲突组被试的stroop任务成绩显著低于低取舍冲突组被试,高、低阅读难度组被试的stroop任务成绩差异不显著;为自己做选择组被试的stroop任务成绩显著低于为他人做选择组被试,完成3选项和4选项任务组被试的stroop任务成绩差异不显著。研究表明,选择损耗效应是由选择的取舍难度而非信息加工难度造成。。     

The lateralized stroop: a meta-analysis and its implications for models of semantic processing

The prevailing theory in the literature concerning the lateralization of Stroop effects involves a speed of processing account (see ). Because the left hemisphere (LH) demonstrates an overall advantage relative to the right hemisphere (RH) on most verbal tasks, interference effects are hypothesized to be greater in the LH than in the RH. Inspection of the data, however, reveals that many studies find no difference in magnitude of Stroop interference between the hemispheres. Given findings within the lateralized semantic priming literature, this is not surprising. A meta-analysis on a subset of lateralized Stroop experiments was conducted to determine whether or not the LH produces significantly more interference than the RH in this paradigm. Based on a number of exclusionary criteria, a total of 19 different studies were included, representing a potential 26 effect size estimates of differential interference. The effect size representing interference using congruent conditions as the baseline (d+=.06) reveals that there is no significant difference between the hemispheres in magnitude of the Stroop interference effect. The LH interference effect was d+=.73, which is significant. Likewise, the RH interference effect, d+=.67, was significant. In summary, while there was no significant difference between the hemispheres, each hemisphere, when examined independently, did exhibit significant within hemisphere interference effects. These findings are presented in light of the lateralized semantic priming literature.     

Neurophysiological evidence for disturbances of conflict processing in patients with schizophrenia

Deficits in cognition are a hallmark of schizophrenia. In the present study, the authors investigated the effects of schizophrenia on the neural correlates of conflict processing in a single-trial version of the Stroop task by using event-related brain potentials. Relative to matched controls, patients with schizophrenia showed increased Stroop interference in response time, but this effect was eliminated when the effect of response slowing was controlled. In controls, conflict processing was associated with a negative wave peaking between 400 and 500 ms (N450) and conflict sustained potential (SP) peaking between 600 and 800 ms after stimulus onset. In patients with schizophrenia, the amplitude of the N450 was significantly attenuated and the conflict SP was absent. These results provide evidence for the existence of altered neural processes associated with conflict processing that may be associated with dysfunction of the anterior cingulate and prefrontal cortex in patients with schizophrenia.     

Evidence accumulation in the integrated and primed Stroop tasks

We report distributional analyses of response times (RT) in two variants of the color-word Stroop task using manual keypress responses. In the classic Stroop task, in which the color and word dimensions are integrated into a single stimulus, the Stroop congruence effect increased across the quantiles. In contrast, in the primed Stroop task, in which the distractor word is presented ahead of colored symbols, the Stroop congruence effect was manifested solely as a distributional shift, remaining constant across the quantiles. The distributional-shift pattern mirrors the semantic-priming effect that has been reported in semantic categorization tasks. The results are interpreted within the framework of evidence accumulation, and implications for the roles of task conflict and informational conflict are discussed.     

Suggestion does not de-automatize word reading: Evidence from the semantically based Stroop task

Recent studies have shown that the suggestion for participants to construe words as meaningless symbols reduces, or even eliminates, standard Stroop interference in highly suggestible individuals (Raz, Fan, & Posner, 2005; Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006). In these studies, the researchers consequently concluded that this suggestion de-automatizes word reading. The aim of the present study was to closely examine this claim. To this end, highly suggestible individuals completed both standard and semantically based Stroop tasks, either with or without a suggestion to construe the words as meaningless symbols (manipulated in both a between-participants [Exp. 1] and a within-participants [Exp. 2] design). By showing that suggestion substantially reduced standard Stroop interference, these two experiments replicated Raz et al.'s (2006) results. However, in both experiments we also found significant semantically based Stroop effects of similar magnitudes in all suggestion conditions. Taken together, these results indicate that the suggestion to construe words as meaningless symbols does not eliminate, or even reduce, semantic activation (assessed by the semantically based Stroop effect) in highly suggestible individuals, and that such an intervention most likely reduces nonsemantic task-relevant response competition related to the standard Stroop task. In sum, contrary to Raz et al.'s claim, suggestion does not de-automatize or prevent reading (as shown by a significant amount of semantic processing), but rather seems to influence response competition. These results also add to the growing body of evidence showing that semantic activation in the Stroop task is indeed automatic.     

The effect of positive affect on conflict resolution: Modulated by approach-motivational intensity

The motivational dimensional model of affect proposes that the influence of positive affect on cognitive processing is modulated by approach-motivational intensity. The present research extended this model by examining the influence of positive affect varying in approach-motivational intensity on conflict resolution—the ability to resolve interference from task-irrelevant distractors in order to focus on the target. The global–local task (Experiment 1) and letter-Flanker task (Experiment 2) were used to measure conflict resolution. Additionally, the 4:2 mapping design that assigns two kinds of task-relevant stimuli to one response key and two more to another response key was used in these two tasks to dissociate stimulus and response conflict. Results showed that positive affect varying in approach motivation had opposite influences on conflict resolution. The opposite influences are primarily reflected in low approach-motivated positive affect impairing, while high approach-motivated positive affect facilitating the resolution of response conflict. Conversely, the stimulus conflict was slightly influenced. These findings highlight the utility of distinguishing stimulus and response conflict in future research.     

基于Flanker、Stroop和Simon多重冲突驱动的认知控制机制

认知控制是维持和调整多任务目标导向的加工策略,而基于多任务冲突的认知控制是一般领域上还是特定领域上,即一种冲突是否会影响另一种冲突的解决,已有研究并没有得到统一的结论。本研究运用事件相关电位（ERP）方法考察了同一任务中不同类型冲突（Stroop、Simon和Flanker冲突）驱动认知控制调节的脑机制。数据显示：各冲突都出现了一致性效应和冲突适应性效应;实验中每种冲突的上一个trial只与该类冲突的当前trial的交互效应显著,而与其他类型冲突的当前trial的交互效应不显著;几乎所有冲突都发现了P300、N450、SP成分一致性效应。结果表明：在不同类型冲突驱动条件下,人脑能够同时监控并解决不同类型的冲突;冲突驱动的认知控制系统以局部的控制方式工作;人脑是基于多冲突驱动的认知控制系统的灵活性和某类型冲突所特有的控制机制来解决冲突,且冲突解决机制是相互独立、互不干扰的。