Working memory capacity and visual attention: Top-down and bottom-up guidance

Previous studies have indicated that working memory capacity (WMC) is related to visual attention when selection of critical information must be made in the face of distraction. The present study examines whether WMC-related differences in flanker task performance might be decreased by displays that are designed to support bottom-up guidance of attention. Participants were required to respond to a centrally located target while ignoring a peripheral flanker. In one condition, bottom-up support was provided by embedding the target in a row of zeros. In another condition, the zeros were removed, thus emphasizing the role of top-down attention in selecting spatially defined information. It was found that the inclusion of zeros led to the elimination of WMC-related flanker effects. We conclude that bottom-up attentional guidance can attenuate the role of WMC in selective attention.     

Working memory capacity and the top-down control of visual search: Exploring the boundaries of "executive attention"

The executive attention theory of working memory capacity (WMC) proposes that measures of WMC broadly predict higher order cognitive abilities because they tap important and general attention capabilities (R. W. Engle & M. J. Kane, 2004). Previous research demonstrated WMC-related differences in attention tasks that required restraint of habitual responses or constraint of conscious focus. To further specify the executive attention construct, the present experiments sought boundary conditions of the WMC-attention relation. Three experiments correlated individual differences in WMC, as measured by complex span tasks, and executive control of visual search. In feature-absence search, conjunction search, and spatial configuration search, WMC was unrelated to search slopes, although they were large and reliably measured. Even in a search task designed to require the volitional movement of attention (J. M. Wolfe, G. A. Alvarez, & T. S. Horowitz, 2000), WMC was irrelevant to performance. Thus, WMC is not associated with all demanding or controlled attention processes, which poses problems for some general theories of WMC.     

社会性信息对Flanker效应的影响

研究显示,面孔Flanker任务中,经典Flanker效应会消失,但其机制还不明确。本文在ANT-I范式的基础上,除常规的箭头Flanker,增加面孔Flanker、两侧为箭头中间为面孔和两侧为面孔中间为箭头的混合Flanker,探究造成该现象的可能原因。结果发现,当Flanker任务中的干扰刺激为箭头时,Flanker效应存在;而干扰刺激为面孔时,Flanker效应则消失了。提示,Flanker任务中干扰刺激的社会性可能是造成Flanker效应消失的原因。这为冲突信息加工中社会性与非社会性信息的控制机制提供了新的视角。     

Escaping capture: bilingualism modulates distraction from working memory

We ask whether bilingualism aids cognitive control over the inadvertent guidance of visual attention from working memory and from bottom-up cueing. We compare highly-proficient Catalan-Spanish bilinguals with Spanish monolinguals in three visual search conditions. In the working memory (WM) condition, attention was driven in a top-down fashion by irrelevant objects held in WM. In the Identify condition, attention was driven in a bottom-up fashion by visual priming. In the Singleton condition, attention was driven in a bottom-up fashion by including a unique distracting object in the search array. The results showed that bilinguals were overall faster than monolinguals in the three conditions, replicating previous findings that bilinguals can be more efficient than monolinguals in the deployment of attention. Interestingly, bilinguals were less captured by irrelevant information held in WM but were equally affected by visual priming and unique singletons in the search displays. These observations suggest that bilingualism aids top-down WM-mediated guidance of attention, facilitating processes that keep separate representations in WM from representations that guide visual attention. In contrast, bottom-up attentional capture by salient yet unrelated input operates similarly in bilinguals and monolinguals.     

The influence of divided attention on holistic face perception.

There is evidence that upright, but not inverted, faces are encoded holistically. The holistic coding of faces was examined in four experiments by manipulating the attention allocated to target faces. In Experiment 1, participants in a divided attention condition were asked to match two upright flanker faces while encoding a centrally presented upright target face. Although holistic coding was evident in the full attention conditions, dividing attention disrupted holistic coding of target faces. In Experiment 2, we found that while matching upright flanker faces disrupted holistic coding, matching inverted flanker faces did not. Experiment 3 demonstrated that the differential effects of flanker orientation were not due to participants taking longer to match upright, than inverted, flanker faces. In Experiment 4, we found that matching fractured faces had an intermediate effect to that of matching upright and inverted flankers, on the holistic coding of the target faces. The findings emphasize the differences in processing of upright, fractured and inverted faces and suggest that there are limitations in the number of faces that can be holistically coded in a brief time.     

The effect of fear and anger on selective attention

This experiment examined the effects of two discrete negative emotions, fear and anger, on selective attention. A within-subjects design was used, and all participants (N = 98) experienced the control, anger, and fear conditions. During each condition, participants viewed a film clip eliciting the target emotion and subsequently completed a flanker task and emotion report. Selective attention costs were assessed by comparing reaction times (RTs) on congruent (baseline) trials with RTs on incongruent trials. There was a significant interaction between emotion condition (control, anger, fear) and flanker type (congruent, incongruent). Contrasts further revealed a significant interaction between emotion and flanker type when comparing RTs in the control and fear conditions, and a marginally significant interaction when comparing RTs in the control and anger conditions. This indicates that selective attention costs were significantly lower in the fear compared to the control condition and were marginally lower in the anger compared with the control condition. Further analysis of participants reporting heightened anger in the anger condition revealed significantly lower selective attention costs during anger compared to a control state. These findings support the general prediction that high arousal negative emotional states inhibit processing of nontarget information and enhance selective attention. This study is the first to show an enhancing effect of anger on selective attention. It also offers convergent evidence to studies that have previously shown an influence of fear on attentional focus using the global-local paradigm.     

Variation in working memory capacity and cognitive control: goal maintenance and microadjustments of control

Variation in working memory capacity (WMC) and cognitive control was examined in four experiments. In the experiments high- and low-WMC individuals performed a choice reaction time task (Experiment 1), a version of the antisaccade task (Experiment 2), a version of the Stroop task (Experiment 3), and an arrow version of the flanker task (Experiment 4). An examination of response time distributions suggested that high- and low-WMC individuals primarily differed in the slowest responses in each experiment, consistent with the notion that WMC is related to active maintenance abilities. Examination of two indicators of microadjustments of control (posterror slowing and conflict adaptation effects) suggested no differences between high- and low-WMC individuals. Collectively these results suggest that variation in WMC is related to some, but not all, cognitive control operations. The results are interpreted within the executive attention theory of WMC.     

Eliminating flanker effects and negative priming in the flankers task: evidence for early selection

Reports of negative priming in the absence of flanker effects (Fox, 1995) provide support for the notion that unattended stimuli are identified. I evaluated the hypothesis that such results are the outcome of attentional leakage to the flanker location. In Experiment 1, I assessed flanker effects and negative priming as a function of target-flanker proximity (.9 degrees and 2.7 degrees for near and far flankers, respectively) and of attention cuing to the target location (precued vs. uncued) on the prime trials. I report larger flanker effects in uncued than in precued conditions, and larger effects for near than for far flankers. More critically, when attention was precued, both flanker effects and negative priming vanished for far flankers. In Experiment 2, I show that the latter result was not linked to prime-probe contextual similarity (Neill, 1997). These results demonstrate that selective target processing is possible when attention is optimally focused to the target location.     

Selective attention and subjective confidence calibration

In the present experiments, failures of selective visual attention were invoked using the B. A. Eriksen and C. W. Eriksen (1974) flanker task. On each trial, a three-letter stimulus array was flashed briefly, followed by a mask. The identity of the two flanking letters was response congruent, neutral, or incongruent with the identity of the middle target letter. On half of the trials, confidence ratings were obtained after each response. In the first three experiments, participants were highly overconfident in the accuracy of their responding to incongruent flanker stimulus arrays. In a final experiment, presenting a prestimulus target location cue greatly reduced both selective attention failure and overconfidence. The findings demonstrate that participants are often unaware of such selective attention failures and provide support for the notion that, in these cases, decisional processing is driven largely by the identities of the incongruent flankers. In addition, responding was invariably slower and sometimes more accurate when confidence was required than when it was not required, demonstrating that the need to provide posttrial confidence reports can affect decisional processing. Moreover, there was some evidence that the presence of neutral contextual flanking information can slow responding, suggesting that such nondiagnostic information can, indeed, contribute to decisional processing.     

Contributions of the human pulvinar to linking vision and action

In 3 patients with unilateral pulvinar lesions, we tested the pulvinar’s role in selective attention processing. Each patient completed four variants of a flanker interference task in which they reported the color of a square of a specified size while ignoring an irrelevant flanker that appeared either contralesionally or ipsilesionally to the target. The main finding was that when target location was not known and target and flanker were associated with competing responses, reaction times to contralesional targets were longer than those to ipsilesional targets. Our findings suggest that pulvinar damage produces a contralesional deficit in response competition.     

Working memory capacity modulates habituation rate: Evidence from a cross-modal auditory distraction paradigm

Habituation of the orienting response is a pivotal part of selective attention, and previous research has related working memory capacity (WMC) to attention control. Against this background, the purpose of this study was to investigate whether individual differences in WMC contribute to habituation rate. The participants categorized visual targets across six blocks of trials. Each target was preceded either by a standard sound or, on rare trials, by a deviant. The magnitude of the deviation effect (i.e., prolonged response time when the deviant was presented) was relatively large in the beginning but attenuated toward the end. There was no relationship between WMC and the deviation effect at the beginning, but there was at the end, and greater WMC was associated with greater habituation. These results indicate that high memory ability increases habituation rate, and they support theories proposing a role for cognitive control in habituation and in some forms of auditory distraction.     

Attentional guidance in singleton search: An examination of top-down,bottom-up,and intertrial factors

While it is clear that the goals of an observer change behaviour, their role in the guidance of visual attention has been much debated. In particular, there has been controversy over whether top-down knowledge can influence attentional guidance in search for a singleton item that is already salient by a bottom-up account (Theeuwes, Reimann, & Mortier, 2006). One suggestion is that passive intertrial priming accounts for what has been called top-down guidance (e.g., Maljkovic & Nakayama, 1994). In the present study, participants responded to the shape of a singleton target among homogenous distractors in a trial-by-trial cueing design. We examined the influence of target expectancy, trial history, and target salience (which was manipulated by changing the number of distractors). Top-down influence resulted in fast RTs that were independent of display size, even on trials that received no priming. Our findings show there is a role for top-down guidance, even in singleton search. The designation of intertrial priming as a bottom-up factor, rather than an implicit top-down factor (Wolfe, Butcher, Lee, & Hyle, 2003), is also discussed.     

Attentional guidance of the eyes by contextual information and abrupt onsets.

Contextual cuing is a memory-based phenomenon in which previously encountered global pattern information in a display can automatically guide attention to the location of a target (Chun & Jiang, 1998), leading to rapid and accurate responses. What is not clear is how contextual cuing works. By monitoring eye movements, we investigated the roles that recognition and guidance play in contextual cuing. Recognition does not appear to occur on every trial and sometimes does not have its effects until later in the search process. When recognition does occur, attention is guided straight to the target rather than in the general direction. In Experiment 2, we investigated the interaction between memory-driven search (contextual cuing) and stimulus-driven attentional capture by abrupt onsets. Contextual cuing was able to override capture by abrupt onsets. In contrast, onsets had almost no effect on the degree of contextual cuing. These data are discussed in terms of the role of top-down and bottom-up factors in the guidance of attention in visual search.     

Working memory capacity predicts conflict-task performance

The relationship between the ability to maintain task goals and working memory capacity (WMC) is firmly established, but evidence for WMC-related differences in conflict processing is mixed. We investigated whether WMC (measured using two complex-span tasks) mediates differences in adjustments of cognitive control in response to conflict. Participants performed a Simon task in which congruent and incongruent trials were equiprobable, but in which the proportion of congruency repetitions (congruent trials followed by congruent trials or incongruent trials followed by incongruent trials) and thus the need for trial-by-trial adjustments in cognitive control varied by block. The overall Simon effect did not depend on WMC capacity. However, for the low-WMC participants the Simon effect decreased as the proportion of congruency repetitions decreased, whereas for the high- and average-WMC participants it was relatively constant across conditions. Distribution analysis of the Simon effect showed more evidence for the inhibition of stimulus location in the low- than in the high-WMC participants, especially when the proportion of congruency repetitions was low. We hypothesize that low-WMC individuals exhibit more interference from task-irrelevant information due to weaker preparatory control prior to stimulus presentation and, thus, stronger reliance on reactive recruitment of cognitive control.     

Lapsed attention to elapsed time? Individual differences in working memory capacity and temporal reproduction

Working memory capacity (WMC) predicts individual differences in a wide range of mental abilities. In three experiments we examined whether WMC would predict temporal judgment. Low-WMC temporal reproductions were consistently too long for the shortest duration and too short for the longest, but were accurate (unbiased) for the intermediate. In contrast, high-WMC temporal reproductions were more accurate (unbiased) across the range. Thus low-WMC showed a classic “migration effect” (Vierordt's Law) to a greater extent than high-WMC. Furthermore reproduction errors depended more on temporal context than the absolute durations of “shortest,” “longest,” and “intermediate.” Low-WMC reproductions were overall more variable than high-WMC. General fluid intelligence (gF) was also related to temporal bias and variability. However, WMC-related timing differences were only attenuated and not eliminated with gF as covariate. Results are discussed in terms of attention, memory, and other psychological constructs.     

Bottom-up guidance in visual search for conjunctions

Understanding the relative role of top-down and bottom-up guidance is crucial for models of visual search. Previous studies have addressed the role of top-down and bottom-up processes in search for a conjunction of features but with inconsistent results. Here, the author used an attentional capture method to address the role of top-down and bottom-up processes in conjunction search. The role of bottom-up processing was assayed by inclusion of an irrelevant-size singleton in a search for a conjunction of color and orientation. One object was uniquely larger on each trial, with chance probability of coinciding with the target; thus, the irrelevant feature of size was not predictive of the target's location. Participants searched more efficiently for the target when it was also the size singleton, and they searched less efficiently for the target when a nontarget was the size singleton. Although a conjunction target cannot be detected on the basis of bottom-up processing alone, participants used search strategies that relied significantly on bottom-up guidance in finding the target, resulting in interference from the irrelevant-size singleton.     

On the relationship between flanker interference and localized attentional interference

The flanker interference (FI) effect suggests that visual attention operates like a mental spotlight, enhancing all stimuli within a selected region. In contrast, other data suggest difficulty dividing attention between objects near one another in the visual field, an effect termed localized attentional interference (LAI). The present experiment examined the relationship between these phenomena. Observers made speeded identity judgments of a colored target letter embedded among gray fillers. A response-compatible or -incompatible flanker of a non-target color appeared at varying distances from the target. Data gave evidence of LAI and spatially-graded FI, with mean RTs and flanker effects both decreasing with target–flanker separation. Both effects were reduced when target location was pre-cued and when the target was of higher salience than the flanker. Results suggest that the distribution of spatial attention modulates the strength of objects competing for selection, with this competition underlying both the FI and LAI effects.     

The Role of Attention in Word Recognition: Results from OB1-Reader

When reading, orthographic information is extracted not only from the word the reader is looking at, but also from adjacent words in the parafovea. Here we examined, using the recently introduced OB1-reader computational model, how orthographic information can be processed in parallel across multiple words and how orthographic information can be integrated across time and space. Although OB1-reader is a model of text reading, here we used it to simulate single-word recognition experiments in which parallel processing has been shown to play a role by manipulating the surrounding context in flanker and priming paradigms. In flanker paradigms, observers recognize a central word flanked by other letter strings located left and right of the target and separated from the target by a space. The model successfully accounts for the finding that such flankers can aid word recognition when they contain bigrams of the target word, independent of where those flankers are in the visual field. In priming experiments, in which the target word is preceded by a masked prime, the model accounts for the finding that priming occurs independent of whether the prime and target word are in the same location or not. Crucial to these successes is the key role that spatial attention plays within OB1-reader, as it allows the model to receive visual input from multiple locations in parallel, while limiting the kinds of errors that can potentially occur under such spatial pooling of orthographic information.     

Testing the attention shift hypothesis as an account for the flanker sequence-based congruency modulation in spatial flanker tasks

Smaller Simon effects when stimulus locations are repeated on successive trials rather than alternated have been explained by the attention shift hypothesis, suggesting that shifts of attention result in interfering response codes. We investigated whether the attention shift hypothesis can also explain smaller flanker effects for repeated flankers than for alternated flankers, which occur only with directional information. In 3 peripheral letter identification tasks, target locations were cued by partial or complete flanker stimuli. Experiments 1 and 2 showed that directional flankers elicit shifts of attention. However, Experiment 3 revealed that directional flankers induced inverted cuing effects when reacting to the central target arrow was additionally required. These results are difficult to reconcile with the attention shift hypothesis as an explanation for the congruency reduction with repetitions of directional flankers.     

Elucidating the Functional Relationship Between Working Memory Capacity and Psychometric Intelligence: A Fixed-Links Modeling Approach for Experimental Repeated-Measures Designs

Numerous studies reported a strong link between working memory capacity (WMC) and fluid intelligence (Gf), although views differ in respect to how close these two constructs are related to each other. In the present study, we used a WMC task with five levels of task demands to assess the relationship between WMC and Gf by means of a new methodological approach referred to as fixed-links modeling. Fixed-links models belong to the family of confirmatory factor analysis (CFA) and are of particular interest for experimental, repeated-measures designs. With this technique, processes systematically varying across task conditions can be disentangled from processes unaffected by the experimental manipulation. Proceeding from the assumption that experimental manipulation in a WMC task leads to increasing demands on WMC, the processes systematically varying across task conditions can be assumed to be WMC-specific. Processes not varying across task conditions, on the other hand, are probably independent of WMC. Fixed-links models allow for representing these two kinds of processes by two independent latent variables. In contrast to traditional CFA where a common latent variable is derived from the different task conditions, fixed-links models facilitate a more precise or purified representation of the WMC-related processes of interest. By using fixed-links modeling to analyze data of 200 participants, we identified a non-experimental latent variable, representing processes that remained constant irrespective of the WMC task conditions, and an experimental latent variable which reflected processes that varied as a function of experimental manipulation. This latter variable represents the increasing demands on WMC and, hence, was considered a purified measure of WMC controlled for the constant processes. Fixed-links modeling showed that both the purified measure of WMC (β = .48) as well as the constant processes involved in the task (β = .45) were related to Gf. Taken together, these two latent variables explained the same portion of variance of Gf as a single latent variable obtained by traditional CFA (β = .65) indicating that traditional CFA causes an overestimation of the effective relationship between WMC and Gf. Thus, fixed-links modeling provides a feasible method for a more valid investigation of the functional relationship between specific constructs.