Flanker and Simon effects interact at the response selection stage

The present study aimed at investigating the processing stage underlying stimulus–stimulus (S–S) congruency effects by examining the relation of a particular type of congruency effect (i.e., the flanker effect) with a stimulus–response (S–R) spatial correspondence effect (i.e., the Simon effect). Experiment 1 used a unilateral flanker task in which the flanker also acted as a Simon-like accessory stimulus. Results showed a significant S–S Congruency × S–R Correspondence interaction: An advantage for flanker–response spatially corresponding trials was observed in target–flanker congruent conditions, whereas, in incongruent conditions, there was a noncorresponding trials' advantage. The analysis of the temporal trend of the correspondence effects ruled out a temporal-overlap account for the observed interaction. Moreover, results of Experiment 2, in which the flanker did not belong to the target set, demonstrated that this interaction cannot be attributed to perceptual grouping of the target–flanker pairs and referential coding of the target with respect to the flanker in the congruent and incongruent conditions, respectively. Taken together, these findings are consistent with a response selection account of congruency effects: Both the position and the task-related attribute of the flanker would activate the associated responses. In noncorresponding-congruent trials and corresponding-incongruent trials, this would cause a conflict at the response selection stage.     

Gender differences on the semantic flanker task using transposed-letter target words

Previous research has demonstrated that men and women are differentially influenced by irrelevant distractors. Other lines of evidence have suggested that increasing the perceptual load of a task reduces distractor interference for participants generally. The present study examined these effects using a semantic version of the flanker task; participants made speeded responses to category target words that were flanked by irrelevant distractors. The response mapping between the target and flanker words was either congruent (mapped to the same motor response) or incongruent (target word mapped to a different motor response to that of the flankers). Target words were presented either normally (e.g., table: low perceptual load) or with the beginning letters transposed (e.g., atble: high perceptual load). The results revealed that women showed a larger congruency effect than men but this was not due to greater interference on incongruent trials. While men and women made faster responses to normal than to transposed target words, this was similar in magnitude. The magnitude of the flanker effect for normal and transposed target words was significantly correlated in men but not in women. These findings are consistent with the view that women may process target words to a deeper level than men and therefore may engage in more conflict monitoring then men.     

知觉负载影响注意选择和冲突解决的系列效应

研究考察了无关侧抑制项引起的侧抑制效应如何受到当前试次知觉负载和先前试次知觉负载与目标?侧抑制项关系的交互影响。被试在视觉搜索集中搜索目标朝向刺激(水平或竖直朝向)并作辨别反应, 非目标项在低负载条件下彼此朝向一致, 在高负载条件下彼此朝向不一致。在搜索集的左侧或右侧存在一个与当前目标一致或不一致的无关侧抑制项(flanker)。结果发现, 整体上, 在当前试次低负载条件下会产生较大的干扰效应, 而在当前试次高负载下无干扰效应。此外, 先前试次(trial n-1)为高负载条件时, 当前试次(trial n)出现了典型的知觉负载效应, 即低负载条件干扰效应较大, 高负载条件无干扰效应。但是, 先前试次为低负载条件时, 当前试次的干扰效应大小受到先前试次冲突解决状态的影响。先前试次为低负载条件且目标?无关侧抑制项不一致时, 下一试次低负载条件的侧抑制效应显著减小, 与高负载条件没有差异; 反之, 先前试次为低负载且目标?侧抑制项一致条件时, 下一试次低负载条件的侧抑制效应显著增大。先前试次为低负载条件时, 完成了知觉加工的侧抑制项或者引发了冲突效应(不一致条件), 或者促进了对目标的反应(一致条件), 造成不同的注意选择和冲突解决状态, 显著影响了下一试次的行为表现。这说明, 注意选择与冲突控制过程是动态变化的, 除了受到当前试次知觉负载的影响, 也受到先前试次注意选择和冲突解决状态的调节。     

Gender differences on the semantic flanker task using transposed-letter target words

Previous research has demonstrated that men and women are differentially influenced by irrelevant distractors. Other lines of evidence have suggested that increasing the perceptual load of a task reduces distractor interference for participants generally. The present study examined these effects using a semantic version of the flanker task; participants made speeded responses to category target words that were flanked by irrelevant distractors. The response mapping between the target and flanker words was either congruent (mapped to the same motor response) or incongruent (target word mapped to a different motor response to that of the flankers). Target words were presented either normally (e.g., table: low perceptual load) or with the beginning letters transposed (e.g., atble: high perceptual load). The results revealed that women showed a larger congruency effect than men but this was not due to greater interference on incongruent trials. While men and women made faster responses to normal than to transposed target words, this was similar in magnitude. The magnitude of the flanker effect for normal and transposed target words was significantly correlated in men but not in women. These findings are consistent with the view that women may process target words to a deeper level than men and therefore may engage in more conflict monitoring then men.     

Effects of mental fatigue on the capacity limits of visual attention

The literature indicates that mental fatigue, due to Time-on-Task (ToT), compromises the ability to ignore distractors. The present study elaborates on this effect by testing whether perceptual load of the target stimuli moderates the ability to ignore distractors under fatigue. Participants (N = 27) performed a visual attention task (an Eriksen flanker task) for 2.5 hours without rest. Target letters were presented at three different perceptual loads and with a peripheral distractor letter. Three target–distractor conditions were tested: congruent, incongruent, and neutral. Results showed that, overall, error rates and reaction times increased with ToT. The detrimental effect of fatigue on performance was most pronounced in the high perceptual load condition. Importantly, however, we also found that fatigue-related ignorance of distractors was compromised in the low perceptual load condition, but not in the medium or high perceptual load condition. This finding is in accordance with the perceptual load theory and refines the knowledge about the declining cognitive performance under fatigue.     

Electrophysiological correlates of crossmodal visual distractor congruency effects: Evidence for response conflict

To investigate the basis of crossmodal visual distractor congruency effects, we recorded event-related brain potentials (ERP) while participants performed a tactile location-discrimination task. Participants made speeded tactile location-discrimination responses to tactile targets presented to the index fingers or thumbs while ignoring simultaneously presented task-irrelevant visual distractor stimuli at either the same (congruent) or a different (incongruent) location. Behavioural results were in line with previous studies, showing slowed response times and increased error rates on incongruent compared with congruent visual distractor trials. To clarify the effect of visual distractors on tactile processing, concurrently recorded ERPs were analyzed for poststimulus, preresponse, and postresponse modulations. An enhanced negativity was found in the time range of the N2 component on incongruent compared with congruent visual distractor trials prior to correct responses. In addition, postresponse ERPs showed the presence of error-related negativity components on incorrect-response trials and enhanced negativity for congruent-incorrect compared with incongruent-incorrect trials. This pattern of ERP results has previously been related to response conflict (Yeung, Botvinick, & Cohen, 2004). Importantly, no modulation of early somatosensory ERPs was present prior to the N2 time range, which may have suggested the contribution of other perceptual or postperceptual processes to crossmodal congruency effects. Taken together, our results suggest that crossmodal visual distractor effects are largely due to response conflict.     

ERP correlates of attentional processing in spider fear: evidence of threat-specific hypervigilance

Attentional bias towards threat can be demonstrated by enhanced processing of threat-related targets and/or greater interference when threat-related distractors are present. These effects are argued to reflect processing within the orienting and executive control networks of the brain respectively. This study investigated behavioural (RT) and electrophysiological correlates of early selective attention and top-down attentional control among females with high (n?=?16) or low (n?=?16) spider fear (Mean age?=?22 years). Participants completed a novel flanker go/nogo task in which a central schematic flower or spider stimulus was flanked by either congruent or incongruent distractors. Participants responded to green stimuli (go trials) and withheld response to yellow stimuli (nogo trials). High fear participants demonstrated significantly shorter reaction times and greater P1 amplitude to spider targets, suggesting specific hypervigilance towards threat-relevant stimuli. In contrast to predictions, there was little evidence for behavioural interference effects or differences in N2 amplitude when distractor stimuli were threat-relevant.     

Counter-regulation in affective attentional biases: a basic mechanism that warrants flexibility in emotion and motivation

We investigated whether anticipating positive or negative future outcomes during goal pursuit has a modulatory effect on attentional biases for affectively congruent and incongruent distractor stimuli. In two experiments using a flanker task, we found that distractor interference of stimuli signaling opportunities or dangers was stronger after inducing an outcome focus of the opposite valence. The second experiment provided additional evidence that the incongruency effect reflects a global shift in affective attentional biases and is not mediated by changes in strategies or in the perceived valence of the stimuli. It is argued that counter-regulation in affective attentional biases serves an important function for the regulation of emotion and action.     

Dude looks like a lady: Exploring the malleability of person categorization

Recent research has documented how single facial features can trigger person categorization. Questions remain, however, regarding the automaticity of the reported effects. Using a modified flanker paradigm, the current investigation explored the extent to which hair cues drive sex categorization when faces comprise task‐irrelevant (i.e., unattended) stimuli. In three experiments, participants were required to classify target forenames by gender while ignoring irrelevant flanking faces with and without hair cues. When present, hair cues were either congruent or incongruent with prevailing cultural stereotypes. The results demonstrated the potency of category‐specifying featural cues. First, flanker interference only emerged when critical hair cues were present (Experiment 1). Second, flankers with stereotype‐incongruent hairstyles (e.g., men with long hair) facilitated access to information associated with the opposite sex (Experiment 2), even when the flankers were highly familiar celebrities (Experiment 3). The theoretical implications of these findings are considered. Copyright © 2009 John Wiley & Sons, Ltd.     

A bottleneck in face identification: repetition priming from flanker images

There is evidence that face processing is capacity-limited in distractor interference tasks and in tasks requiring overt recognition memory. We examined whether capacity limits for faces can be observed with a more sensitive measure of visual processing, by measuring repetition priming of flanker faces that were presented alongside a face or a nonface target. In Experiment 1, we found identity priming for face flankers, by measuring repetition priming across a change in image, during task-relevant nonface processing, but not during the processing of a concurrently-presented face target. Experiment 2 showed perceptual priming of the flanker faces, across identical images at prime and test, when they were presented alongside a face target. In a third Experiment, all of these effects were replicated by measuring identity priming and perceptual priming within the same task. Overall, these results imply that face processing is capacity limited, such that only a single face can be identified at one time. Merely attending to a target face appears sufficient to trigger these capacity limits, thereby extinguishing identification of a second face in the display, although our results demonstrate that the additional face remains at least subject to superficial image processing.     

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.     

Does response interference depend on the subjective visibility of flanker distractors?

Response interference (or response conflict) refers to the phenomenon whereby response times to a target stimulus are longer in the presence of distractor stimuli that indicate contrary motor responses. Response interference has been observed even when the distractor stimuli cannot be discriminated above chance levels. These results raise the question of whether response interference might be driven automatically by the physical distractor stimuli, independently of one??s subjective perception of the distractors. Using a modified version of the Eriksen flanker task, we applied metacontrast masks to the flanker stimuli and measured their subjective visibility after each trial. We found converging lines of evidence that the subjective perception of flankers contributed to response interference, over and above the contribution of automatic processing of the stimulus itself. A factorial analysis revealed that the objective, physical congruency of target and flankers and the subjective, perceptual congruency of target and flankers make additive, noninteracting contributions to target response interference, suggesting that the two interference effects originate from independent levels or stages of cognitive processing.     

Attention and gaze shifting in dual-task and go/no-go performance with vocal responding

Evidence from go/no-go performance on the Eriksen flanker task with manual responding suggests that individuals gaze at stimuli just as long as needed to identify them (e.g., Sanders, 1998). In contrast, evidence from dual-task performance with vocal responding suggests that gaze shifts occur after response selection (e.g., Roelofs, 2008a). This difference in results may be due to the nature of the task situation (go/no-go vs. dual task) or the response modality (manual vs. vocal). We examined this by having participants vocally respond to congruent and incongruent flanker stimuli and shift gaze to left- or right-pointing arrows. The arrows required a manual response (dual task) or determined whether the vocal response to the flanker stimuli had to be given or not (go/no-go). Vocal response and gaze shift latencies were longer on incongruent than congruent trials in both dual-task and go/no-go performance. The flanker effect was also present in the manual response latencies in dual-task performance. Ex-Gaussian analyses revealed that the flanker effect on the gaze shifts consisted of a shift of the entire latency distribution. These results suggest that gaze shifts occur after response selection in both dual-task and go/no-go performance with vocal responding.     

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.     

Investigating the modality specificity of response selection using a temporal flanker task

The neurocognitive architecture for response selection is uncertain. Some theorists suggest that it is mediated by an amodal central mechanism, whereas others propose a set of independent control mechanisms. In a functional neuroimaging experiment, we investigated the nature of response selection by examining how its underlying brain mechanisms are affected by stimulus modality. To do this, we used a modified flanker task, in which the target and flanker (distractor) stimuli differed in time rather than space, making it accessible for both visual and auditory stimuli. As in the traditional flanker task, larger reaction times were observed for incongruent than congruent trials (i.e., a congruency effect) for both modalities. Congruency affected brain activation for both modalities in prefrontal cortex, parietal cortex, and the putamen. Modality-dependent activation was found in additional prefrontal and parietal regions for the visual modality and in left inferior prefrontal cortex for the auditory modality. Modality-dependent activity specifically related to response congruency was also found in sensory cortical regions. These data suggest that modality affects the brain regions throughout the cortex mediating response selection even for conceptually identical stimuli and tasks. They are consistent with the hypothesis that (at least partially) independent brain networks mediate response selection and that input modality may be a powerful factor for organizing neural activity to support task performance.     

Race and gender of faces can be ignored

Past research indicates that faces can be more difficult to ignore than other types of stimuli. Given the important social and biological relevance of race and gender, the present study examined whether the processing of these facial characteristics is mandatory. Both unfamiliar and famous faces were assessed. Participants made speeded judgments about either the race (Experiment 1) or gender (Experiments 2–4) of a target name under varying levels of perceptual load, while ignoring a flanking distractor face that was either congruent or incongruent with the race/gender of the target name. In general, distractor–target congruency effects emerged when the perceptual load of the relevant task was low but not when the load was high, regardless of whether the distractor face was unfamiliar or famous. These findings suggest that face processing is not necessarily mandatory, and some aspects of faces can be ignored.     

Stimulus repetition effects on texture-based visual search by pigeons

Four experiments investigated the effects of within-session stimulus repetition on texture discrimination. Six pigeons (Columba livia) searched for a contrasting target region (color or shape) randomly embedded within a larger distractor region for food reinforcement. Experiment 1 found that repeating features of the distractors, but not those of the target, across trials increased the accuracy of target localization relative to baseline. Experiment 2 found that subsequently switching the identity of a repeated distractor feature to the target decreased accuracy. Experiment 3 found that the effects of repeating a distractor feature influenced search performance for at least 60 trials after this learning. Experiment 4 found that differential stimulus-outcome relations can produce control by repeated target features. The results are discussed in terms of the factors and strategies involved in the control of avian visual search behavior.     

The interaction between stop signal inhibition and distractor interference in the flanker and Stroop task

In the present study, two experiments were conducted to investigate the interaction between the behavioral inhibition, measured by the stop signal task, and distractor interference, measured by the flanker task and the Stroop task. In the first experiment, the stop signal task was combined with a flanker task. Analysis revealed that participants responded faster when the distractors were congruent to the target. Also, the data suggest that it is more difficult to suppress a reaction when the distractors were incongruent. Whether the incongruent distractor was part of the response set (i.e. the distractor could also be a target) or not, had no influence on stopping reactions. In the second experiment, the stop signal task was combined with a manual version of the Stroop task and the degree of compatibility was varied. Even though in the second experiment of the present study interference control is differently operationalized, similar results as in the first experiment were found, indicating that inhibition of motor responses is influenced by the presentation of distracting information that is not part of the response set.     

The inability to ignore auditory distractors as a function of visual task perceptual load

Using a response competition paradigm, we investigated the ability to ignore target response-compatible, target response-incompatible, and neutral visual and auditory distractors presented during a visual search task. The perceptual load model of attention (e.g., Lavie & Tsal, 1994) states that task-relevant processing load determines irrelevant distractor processing in such a way that increasing processing load prevents distractor processing. In three experiments, participants searched sets of one (easy search) or six (hard search) similar items. In Experiment 1, visual distractors influenced reaction time (RT) and accuracy only for easy searches, following the perceptual load model. Surprisingly, auditory distractors yielded larger distractor compatibility effects (median RT for incompatible trials minus median RT for compatible trials) for hard searches than for easy searches. In Experiments 2 and 3, during hard searches, consistent RT benefits with response-compatible and RT costs with response-incompatible auditory distractors occurred only for hard searches. We suggest that auditory distractors are processed regardless of visual perceptual load but that the ability to inhibit cross-modal influence from auditory distractors is reduced under high visual load.