Electrophysiological evidence for greater attention to threat when cognitive control resources are depleted

In this study, we investigated the time course of attentional bias for threat-related (angry) facial expressions under conditions of high versus low cognitive (working memory) load. Event-related potential (ERP) and reaction time (RT) data were recorded while participants viewed pairs of faces (angry paired with neutral face) displayed for 500 ms and followed by a probe. Participants were required to respond to the probe while performing a concurrent task of holding in working memory a sequence of digits that were either in the same order (low memory load) or in a random mixed order (high memory load). The ERP results revealed that higher working memory load resulted in enhanced lateralized neural responses to threatening relative to neutral faces, consistent with greater initial orienting of attention to threatening faces (early N2pc: 180–252 ms) and enhanced maintenance of processing representations of threat (late N2pc, 252–320 ms; SPCN, 320–500 ms). The ERP indices showed significant positive relationships with each other, and also with the behavioral index of attentional bias to threat (reflected by faster RTs to probes replacing angry than neutral faces at 500 ms), although the latter index was not significantly influenced by memory load. Overall, the findings indicate that depletion of cognitive control resources, using a working memory manipulation, increases the capacity of task-irrelevant threat cues to capture and hold attention.     

Testing whether gaze cues and arrow cues produce reflexive or volitional shifts of attention

It has been suggested that two types of uninformative central cues produce reflexive orienting: gaze and arrow cues. Using the criterion that voluntary shifts of attention facilitate both response speed and perceptual accuracy, whereas reflexive shifts of attention facilitate only response speed (Prinzmetal, McCool, & Park, 2005), we tested whether these cues produce reflexive or volitional shifts of attention. A cued letter discrimination task was used with both gaze (Experiments 1A and 1B) and arrow (Experiments 2A and 2B) cues, in which participants responded to the identity of the target letter. In the response time (respond speed) tasks, participants were asked to respond as quickly as possible to the target; in the accuracy (perceptual quality) tasks, participants were asked to respond as accurately as possible. For both cue types, compatible cues were found to facilitate response speed but not perceptual accuracy, indicating that both gaze and arrow cues generate reflexive shifts in attention.     

Effects of aging on voluntary and involuntary shifts of attention

Abstract

This experiment examined adult age differences in the speed and accuracy of voluntary and involuntary shifts of visual attention. Younger and older adults performed two spatial cuing tasks using central cues and abrupt onset peripheral cues presented at stimulus onset asynchronies (SOAs) of 100, 150, 200, 250, and 300 ms. Analyses of the magnitudes of cuing effects revealed a similar time course for younger and older adults in the central cue condition, but not in the peripheral condition. Analyses of the Brinley plot for central cues across cue validity conditions indicated that as much as 93% of the variance could be attributed to age-related general slowing rather than to differential aging of a specific visual orienting mechanism.     

Postural Mechanisms to Control Body Displacements in the Performance of Lateral Gaze Shifts

Medialateral postural control mechanisms (bodyweight distribution and center of pressure location) have been studied in static conditions. Our objective was to determine how these mechanisms are adjusted to perform voluntary movements, in our case 80° lateral gaze shifts at 0.125 Hz and 0.25 Hz. In healthy, young adults, we expected body marker (neck, lower back) and center of pressure displacements to be significantly greater in gaze shift conditions than in the stationary gaze condition. To explain these changes in center of pressure displacement, the amplitude contribution of both mechanisms was expected to increase significantly. All these results were found accordingly. Unexpectedly, the active contribution of the bodyweight distribution mechanism was negatively related to body marker displacements in the gaze shift conditions (ns in stationary condition). Moreover, changes in the contribution of the mechanisms were statistically weaker in effect size than changes in body displacement. However, the participants were not unstable because they performed the visual tasks as requested. We propose that the strength of medialateral postural control mechanisms may not only be strengthened to control challenging ML stance conditions but also slightly weakened to allow the performance of adequate body motions in ongoing tasks.     

A methodological note on evaluating performance in a sustained-attention-to-response task

We evaluated the influence of speed–accuracy trade-offs on performance in the sustained attention to response task (SART), a task often used to evaluate the effectiveness of techniques designed to improve sustained attention. In the present study, we experimentally manipulated response delay in a variation of the SART and found that commission errors, which are commonly used as an index of lapses in sustained attention, were a systematic function of manipulated differences in response delay. Delaying responses to roughly 800 ms after stimulus onset reduced commission errors substantially. We suggest the possibility that any technique that affects response speed will indirectly alter error rates independently of improvements in sustained attention. Investigators therefore need to carefully explore, report, and correct for changes in response speed that accompany improvements in performance or, alternatively, to employ tasks that control for response speed.     

The effect of mild depression on time discrimination

Depressed mood states affect subjective perceptions of time but it is not clear whether this is due to changes in the underlying timing mechanisms, such as the speed of the internal clock. In order to study depression effects on time perception, two experiments using time discrimination methods with short (<300 ms) and long (>1,000 ms) durations were conducted. Student participants who were categorized as mildly depressed by their scores on the Beck Depression Inventory were less able than controls to discriminate between two longer durations but were equally able to discriminate shorter intervals. The results suggest that mildly depressed or dysphoric moods do not affect pacemaker speed. It is more likely that depression affects the ability to maintain attention to elapsing duration.     

Working-memory capacity predicts the executive control of visual search among distractors: The influences of sustained and selective attention

Variation in working-memory capacity (WMC) predicts individual differences in only some attention-control capabilities. Whereas higher WMC subjects outperform lower WMC subjects in tasks requiring the restraint of prepotent but inappropriate responses, and the constraint of attentional focus to target stimuli against distractors, they do not differ in prototypical visual-search tasks, even those that yield steep search slopes and engender top-down control. The present three experiments tested whether WMC, as measured by complex memory span tasks, would predict search latencies when the 1–8 target locations to be searched appeared alone, versus appearing among distractor locations to be ignored, with the latter requiring selective attentional focus. Subjects viewed target-location cues and then fixated on those locations over either long (1,500–1,550 ms) or short (300 ms) delays. Higher WMC subjects identified targets faster than did lower WMC subjects only in the presence of distractors and only over long fixation delays. WMC thus appears to affect subjects' ability to maintain a constrained attentional focus over time.     

A new estimation of the duration of attentional dwell time

How rapidly can attention move from one object to the next? Previous studies in which the dwell time paradigm was used have estimated attentional switch times of 200–500 msec, results incompatible with the search rate estimates of 25–50 msec shown in numerous visual search studies. It has been argued that dwell times are so long in the dwell time paradigm because the attentional shifts measured are unlike those used in visual search. In the present experiment, a variation of a visual search task was used, in which serial endogenous (volitional) deployments of attention were measured directly by means of a probe reaction time task. The experiment revealed a dwell time of about 250 msec, consistent with the faster estimates from other dwell time studies. This result suggests that endogenous shifts of attention may be relatively slow and that the faster attentional shifts estimated from visual search tasks may be due to the involvement of bottom-up processes.     

Wait a second: Brief delays in responding reduce focality effects in event-based prospective memory

Remembering to perform deferred actions when an event is encountered in the future is referred to as event-based prospective memory (PM). We examined whether the failure of individuals to allocate sufficient attentional resources to nonfocal PM tasks can be linked to the response demands inherent in PM paradigms that require the PM task to race for response selection with the speeded ongoing task. In three experiments, participants performed a lexical decision task while being required to make a separate PM response to a specific word (focal), an exemplar of a category (nonfocal), or a syllable (nonfocal). We manipulated the earliest time participants could make task responses by presenting a tone at varying onsets (0–1,600 ms) following stimulus presentation. Improvements in focal PM and nonfocal PM were observed at response delays as brief as 200 ms and 400 ms, respectively. Nonfocal PM accuracy was comparable to focal PM accuracy at delays of 600 ms and 1,600 ms for categorical targets and syllable targets, respectively. Delaying task responses freed the resource-demanding processing operations used on the ongoing task for use on the nonfocal PM task, increasing the probability that the nonfocal PM features of ongoing task stimuli were adequately assessed prior to the ongoing task response.     

Reflexive orienting in response to short- and long-duration gaze cues in young,young-old,and old-old adults

Shifting visual focus on the basis of the perceived gaze direction of another person is one form of joint attention. In the present study, we investigated whether this socially relevant form of orienting is reflexive and whether it is influenced by age. Green and Woldorff (Cognition 122:96–101, 2012) argued that rapid cueing effects (i.e., faster responses to validly than to invalidly cued targets) were limited to conditions in which a cue overlapped in time with a target. They attributed slower responses following invalid cues to the time needed to resolve the incongruent spatial information provided by the concurrently presented cue and target. In the present study, we examined the orienting responses of young (18–31 years), young-old (60–74 years), and old-old (75–91 years) adults following uninformative central gaze cues that overlapped in time with the target (Exp. 1) or that were removed prior to target presentation (Exp. 2). When the cue and target overlapped, all three groups localized validly cued targets more quickly than invalidly cued targets, and validity effects emerged earlier for the two younger groups (at 100 ms post-cue-onset) than for the old-old group (at 300 ms post-cue-onset). With a short-duration cue (Exp. 2), validity effects developed rapidly (by 100 ms) for all three groups, suggesting that validity effects resulted from reflexive orienting based on the gaze cue information rather than from cue–target conflict. Thus, although old-old adults may be slow to disengage from persistent gaze cues, attention continues to be reflexively guided by gaze cues late in life.     

眼睛注视线索提示效应: 内源性注意还是外源性注意?

采用改进的Posner视-空间线索提示范式, 对眼睛注视线索提示效应(eyes gaze cueing effect)的加工机制进行了探讨。实验一考察注视提示线索对空间Stroop效应的影响; 实验二考察注视提示线索对特征抽取和特征整合的影响。实验结果显示: 注视线索提示有效时的空间Stroop效应显著大于提示无效的情景; 在单一特征搜索与特征联合搜索任务中, 注视线索提示效应无差别。这说明, 注视线索通过在头脑里形成空间方位表征诱导注意转移; 注视线索通过影响特征抽取、而非特征整合阶段, 对客体加工产生易化。本研究支持注视线索提示效应属于内源性注意的观点。     

Le TASC200, une épreuve d’attention et de saillance visuelle : fidélité, validité et normes préliminaires

In the clinical setting, attention is classically assessed by tasks that do not take into account theoretically important aspects, such as the salience-based guidance of visual search. The aim of this study was to develop a paced paper-and-pencil task for clinical use based on strong theoretical accounts that would assess salience-based visual search and that would meet the psychometric requirements for the assessment of attention. Participants were required to search and cancel targets of varying visual saliences as quickly and as accurately as possible during a predefined short period of time. The targets were intermixed with distractors. In agreement with theories of salience-based visual search, the results showed that the most salient targets were detected more easily than less salient targets. The task exhibited a quite acceptable test-retest reliability, and two construct validity studies showed that different scores involve different processes. This new task fully complies with the major theories of salience-based guidance of attention during visual search. It also meets the requirements of a plausible clinical task since its psychometric qualities are quite good. Preliminary normative data (n = 863) are presented for clinical use.     

Preliminary validation study of the 3-min wrist-worn psychomotor vigilance test

The 10-min psychomotor vigilance test (PVT) is a widely used tool to assess behavioral alertness. In operational environments, however, the 3-min version of the PVT is more practicable. Under controlled laboratory conditions, we compared performance on the 3-min PVT on a wrist-worn device with the 3-min PVT on a laptop computer. We conducted two repeated measures experiments (72 participants) to assess the effects of PVT device type (laptop or wrist-worn), backlight on the wrist-worn device (on or off), ambient light (low or normal levels), and interstimulus interval (ISI). First, we compared the wrist-worn PVT (ISI of 2–10 s) with the laptop-based PVT (ISI of 1–4 s). Participants performed six PVT trials counterbalanced for order of ambient light and device type. In both ambient-lighting conditions, the median differences in PVT metrics (reaction time, response speed, and percentage of 355-ms or 500-ms lapses combined with false starts) between the laptop and the wrist-worn PVT with the backlight on were less than 4.5 %. Specifically, the median difference in reaction times was less than 10 ms. However, the standard deviation in most metrics using the wrist-worn PVT was twice that of the laptop. In a second experiment, we compared the wrist-worn and laptop PVTs with the same ISIs (1–4 s) in normal light conditions. The results suggest that PVT data can be collected reliably in the field using the wrist-worn device with the backlight on and an ISI of 2–10 s.     

Visual search for arbitrary objects in real scenes

How efficient is visual search in real scenes? In searches for targets among arrays of randomly placed distractors, efficiency is often indexed by the slope of the reaction time (RT) × Set Size function. However, it may be impossible to define set size for real scenes. As an approximation, we hand-labeled 100 indoor scenes and used the number of labeled regions as a surrogate for set size. In Experiment 1, observers searched for named objects (a chair, bowl, etc.). With set size defined as the number of labeled regions, search was very efficient (~5 ms/item). When we controlled for a possible guessing strategy in Experiment 2, slopes increased somewhat (~15 ms/item), but they were much shallower than search for a random object among other distinctive objects outside of a scene setting (Exp. 3: ~40 ms/item). In Experiments 4–6, observers searched repeatedly through the same scene for different objects. Increased familiarity with scenes had modest effects on RTs, while repetition of target items had large effects (>500 ms). We propose that visual search in scenes is efficient because scene-specific forms of attentional guidance can eliminate most regions from the “functional set size” of items that could possibly be the target.     

Measuring the time course of selection during visual search

In visual search tasks, observers can guide their attention towards items in the visual field that share features with the target item. In this series of studies, we examined the time course of guidance toward a subset of items that have the same color as the target item. Landolt Cs were placed on 16 colored disks. Fifteen distractor Cs had gaps facing up or down while one target C had a gap facing left or right. Observers searched for the target C and reported which side contained the gap as quickly as possible. In the absence of other information, observers must search at random through the Cs. However, during the trial, the disks changed colors. Twelve disks were now of one color and four disks were of another color. Observers knew that the target C would always be in the smaller color set. The experimental question was how quickly observers could guide their attention to the smaller color set. Results indicate that observers could not make instantaneous use of color information to guide the search, even when they knew which two colors would be appearing on every trial. In each study, it took participants 200–300 ms to fully utilize the color information once presented. Control studies replicated the finding with more saturated colors and with colored C stimuli (rather than Cs on colored disks). We conclude that segregation of a display by color for the purposes of guidance takes 200–300 ms to fully develop.     

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.     

Tracking the first two seconds: three stages of visual information processing?

We compared visual priming and comparison tasks to assess information processing of a stimulus during the first 2 s after its onset. In both tasks, a 13-ms prime was followed at varying SOAs by a 40-ms probe. In the priming task, observers identified the probe as rapidly and accurately as possible; in the comparison task, observers determined as rapidly and accurately as possible whether or not the probe and prime were identical. Priming effects attained a maximum at an SOA of 133 ms and then declined monotonically to zero by 700 ms, indicating reliance on relatively brief visuosensory (iconic) memory. In contrast, the comparison effects yielded a multiphasic function, showing a maximum at 0 ms followed by a minimum at 133 ms, followed in turn by a maximum at 240 ms and another minimum at 720 ms, and finally a third maximum at 1,200 ms before declining thereafter. The results indicate three stages of prime processing that we take to correspond to iconic visible persistence, iconic informational persistence, and visual working memory, with the first two used in the priming task and all three in the comparison task. These stages are related to stages presumed to underlie stimulus processing in other tasks, such as those giving rise to the attentional blink.     

Textures shape the attentional focus: Evidence from exogenous and endogenous cueing

The spatial cueing paradigm (Posner Quarterly Journal of Experimental Psychology 32:3–25, 1980) has often been used to investigate the time course of the deployment of visual attention in space. In a series of eight experiments we investigated whether spatial cues would not only enhance processing of stimuli presented at cued locations, but also enhance processing of the entire texture in which the stimuli were presented. Results showed highest accuracy for responses to stimuli presented at cued locations, a replication of the traditional cueing effect (Posner 1980). Additionally, stimuli presented at uncued locations were responded to with higher accuracy when they were presented inside the same texture as the cued location, as compared with stimuli presented outside the texture with the cued location. To investigate this texture advantage for both automatic and voluntary attention deployment, exogenous and endogenous cues were used. The texture advantage was observed for short interstimulus intervals (ISIs) of 50 and 100 ms for exogenous cues and for a longer ISI of 200 ms for endogenous cues. These findings indicate that the arrangement of task-irrelevant visual stimuli also can have a large impact on the cueing effect. This suggests that visual spatial attention spreads texture-wise across the visual field. Control experiments revealed that the homogeneity within texture elements contributes most to the effect but that the texture advantage is a function of both orientation contrast at the texture border and homogeneity within texture elements.     

Serial deployment of attention during visual search

This study examined whether objects are attended in serial or in parallel during a demanding visual search task. A component of the event-related potential waveform, the N2pc wave, was used as a continuous measure of the allocation of attention to possible targets in the search arrays. Experiment 1 demonstrated that the relative allocation of attention shifts rapidly, favoring one item and then another. In Experiment 2, a paradigm was used that made it possible to track the absolute allocation of attention to individual items. This experiment showed that attention was allocated to one object for 100-150 ms before attention began to be allocated to the next object. These findings support models of attention that posit serial processing in demanding visual search tasks.     

Polymorphism in the CHRNA4 gene is associated with rapid scene categorization performance

The CHRNA4 gene is known to be associated with individual differences in attention. However, its associations with other cognitive functions remain to be elucidated. In the present study, we investigated the effects of genetic variations in CHRNA4 on rapid scene categorization by 100 healthy human participants. In Experiment 1, we also conducted the Attention Network Test (ANT) in order to examine whether the genetic effects could be accounted for by attention. CHRNA4 was genotyped as carrying the TT, CT, or CC allele. The scene categorization task required participants to judge whether the category of a scene image (natural or man-made) was consistent with a cue word displayed at the response phase. The target–mask stimulus onset asynchrony (SOA) ranged from 13 to 93 ms. In comparison with CC-allele carriers, CT- and TT-allele carriers responded more accurately at the long SOA (93 ms) only during natural-scene categorization. In contrast, we observed no consistent association between CHRNA4 and the ANT, and no intertask correlation between scene categorization and the ANT. To validate our natural-scene categorization results, Experiment 2, carried out with an independent sample of 100 participants and a different stimulus set, successfully replicated the association between CHRNA4 genotypes and natural-scene categorization accuracy at long SOAs (67 and 93 ms). Our findings demonstrate, for the first time, that genetic variations in CHRNA4 can moderately contribute to individual differences in natural-scene categorization performance.