How to keep attention from straying: Get engaged!

Previous research has suggested that the involuntary allocation of spatial attention to salient, irrelevant stimuli (i.e., attentional capture) is prevented when attention is in a focused state (e.g., Yantis & Jonides, 1990). Recent work has suggested that although focused attention may be necessary to prevent attentional capture by irrelevant stimuli, it is not sufficient (e.g., Folk, Leber, & Egeth, 2002). The present experiments provide evidence that attentional engagement, rather than attentional focusing, prevents capture. Observers performed a rapid serial visual presentation task in which they were asked to identify a target letter defined by color. Peripheral distractors that shared the color of the target produced evidence of attentional capture. This effect was completely eliminated, however, when the peripheral distractor was preceded by a central distractor designed to engage attention on the stream. It is concluded that attentional engagement serves to lock out capture by irrelevant, salient stimuli.     

Attention meets binding: Only attended distractors are used for the retrieval of event files

Response-irrelevant stimuli can be encoded with, and later on retrieve, a response given to a relevant stimulus, an effect that is called distractor–response binding. In three experiments using a prime–probe design, we investigated whether the allocation of attention modulates the processes contributing to distractor–response binding. Participants identified letters via keypresses while attending to one of two sets of simultaneously presented but response-irrelevant number stimuli. In different experiments, both spatial attention and feature-based attention were allocated to the response-irrelevant stimuli. The results showed that only attended response-irrelevant stimuli elicited effects of distractor–response binding. In particular, while the encoding of response-irrelevant stimuli and responses was not particularly affected by attention during prime processing, only attended response-irrelevant stimuli in the probe retrieved previous responses. Hence, we show that attention affects action regulation due to modulating the influence of stimulus–response binding on behavior.     

The effect of novel distractors on performance in focused attention tasks: A cognitive-psychophysiological approach

In the present study, we examined whether or not novel stimuli affect performance in a focused attention task. Participants responded to a central target while an irrelevant distractor in the visual display was occasionally changed. In Experiment 1, both target and distractor were presented centrally within the focus of attention. In Experiment 2, a central target was presented along with an irrelevant distractor at a peripheral location, outside the focus of attention. Novel distractors were associated with longer latencies and enhanced orienting responses (as measured by skin conductance responses) only when presented at an attended location. In contrast, as is demonstrated in Experiment 3, the same peripheral novel distractors interfered with task performance when they possessed task-relevant information. These results indicate that there is a fundamental difference between novel stimuli and task-relevant stimuli. Whereas the former exert influence only within the focus of attention, the latter affect performance even when positioned in an unattended location. Our findings have important implications for the operation of visual attention.     

How does reward compete with goal-directed and stimulus-driven shifts of attention?

In order to behave adaptively, attention can be directed in space either voluntarily (i.e. endogenously) according to strategic goals, or involuntarily (i.e. exogenously) through reflexive capture by salient or novel events. The emotional or motivational values of stimuli can also influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms. Here we designed a visual search paradigm in which goal-driven and stimulus-driven shifts of attention were manipulated by classic spatial cueing procedures, while an irrelevant, but previously rewarded stimulus also appeared as a distractor and hence competed with both types of spatial attention during search. Our results demonstrated that stimuli previously associated with a high monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, mitigating the attentional orienting induced by both endogenous and exogenous cues.     

Contingent attentional capture occurs by activated target congruence

Contingent attentional capture occurs when a stimulus property captures an observer's attention, usually related to the observer's top-down attentional set for target-defining properties. In this study, we examined whether contingent attentional capture occurs for a distractor that does not share the target-defining property at a physical level, but does share that property at an abstract level of representation. In a rapid serial visual presentation stream, we defined the target by color (e.g., a green-colored Japanese kanji character). Before the target onset, we presented a distractor that referred to the target-defining color (e.g., a white-colored character meaning "green"). We observed contingent attentional capture by the distractor, which was reflected by a deficit in identifying the subsequent target. This result suggests that because of the attentional set, stimuli were scanned on the basis of the target-defining property at an abstract semantic level of representation.     

Distractor-response bindings in dual task scenarios

If a response is executed in reaction to a target stimulus, accompanying distractor stimuli can be integrated with and later on retrieve this response, an effect called distractor-response binding. There has been some debate as to whether S-R binding is generally influenced by attentional processes and in particular the role of attentional processes for the binding of irrelevant stimuli and responses is unclear. We therefore analyze the impact of spatial input attention while engaging central attention in an additional task. In particular, participants worked in dual task situations that induced load on central attention while the distribution of spatial attention was manipulated by varying the location of the different tasks. Distractor-response binding occurred only if both tasks were presented in the same spatial location. In contrast, binding effects within one task were prevented if spatial attention was withdrawn from the task by presenting a second task in a separate area. It is concluded that input but no central attention is required for the integration of distractor stimuli and responses. Theoretical and practical implications of these findings are discussed.     

Distracted by danger: Temporal and spatial dynamics of visual selection in the presence of threat

Threatening stimuli are known to influence attentional and visual processes in order to prioritize selection. For example, previous research showed faster detection of threatening relative to nonthreatening stimuli. This has led to the proposal that threatening stimuli are prioritized automatically via a rapid subcortical route. However, in most studies, the threatening stimulus is always to some extent task relevant. Therefore, it is still unclear if threatening stimuli are automatically prioritized by the visual system. We used the additional singleton paradigm with task-irrelevant fear-conditioned distractors (CS+ and CS-) and indexed the time course of eye movement behavior. The results demonstrate automatic prioritization of threat. First, mean latency of saccades directed to the neutral target was increased in the presence of a threatening (CS+) relative to a nonthreatening distractor (CS-), indicating exogenous attentional capture and delayed disengagement of covert attention. Second, more error saccades were directed to the threatening than to the nonthreatening distractor, indicating a modulation of automatically driven saccades. Nevertheless, cumulative distributions of the saccade latencies showed no modulation of threat for the fastest goal-driven saccades, and threat did not affect the latency of the error saccades to the distractors. Together these results suggest that threatening stimuli are automatically prioritized in attentional and visual selection but not via faster processing. Rather, we suggest that prioritization results from an enhanced representation of the threatening stimulus in the oculomotor system, which drives attentional and visual selection. The current findings are interpreted in terms of a neurobiological model of saccade programming.     

Spatial selection via feature-driven inhibition of distractor locations

The allocation of spatial attention was measured with detection probes at different locations. Response times were faster for probes at the location of the target digit, which subjects reported, than at the locations of distractor digits, which they ignored. Probes at blank locations between stimuli produced fast responses, indicating that selection was accomplished by inhibiting distractor locations but not other areas. Unlike earlier studies using location cuing with simpler stimuli, these experiments showed no attentional differences across horizontal or vertical midlines. Attention varied little with distance from the target, although blank locations far from the target were somewhat less attended than were those near the target, and attention was only slightly affected by expectations for stimulus location. This task demonstrates a form of feature-driven spatial attention, in which locations with objects lacking target features are inhibited.     

场景在价值驱动注意捕获中的作用

本研究采用训练-测试范式考察场景信息在价值驱动注意捕获中的作用。实验1训练阶段将唯一性的场景信息与奖励建立联结,测试阶段发现只有当分心刺激出现在高奖励场景中才能捕获注意;实验2训练阶段将场景和颜色信息联合但分别独立预测奖励,结果发现高奖励颜色出现在任何场景中都能捕获注意。研究结果表明:(1)场景-价值联结能够引发注意捕获效应;(2)与场景相比,颜色特征在价值驱动的注意捕获中具有优势效应。     

Does ignoring lead to worse evaluations? A new explanation of the stimulus devaluation effect

Affective evaluation of stimuli just seen in visual search tasks has been shown to depend on task-relevant stimulus configuration (Raymond, Fenske, & Tavassoli, 2003): Whereas targets and novel stimuli were evaluated similarly, distractors were devaluated. These results were explained by an inhibition-based account of the influence of selective attention on emotion. In the present experiments, we demonstrated that stimulus devaluation might not be a consequence of attentional inhibition. By simply instructing participants to react to an accepted or rejected stimulus in the visual search task of Experiment 1, we found distractor devaluation in the first case and target devaluation in the second case. We conclude that devaluation of stimuli is mediated by the affective connotation implied by response labels and instructions. This was confirmed in Experiment 2: To-be-ignored stimuli were not devaluated when participants knew that those stimuli would become task-relevant during the experiment.     

Attentional engagement is not sufficient to prevent spatial capture

What conditions, if any, can fully prevent attentional capture (i.e., involuntary allocation of spatial attention to an irrelevant object) has been a matter of debate. In a previous study, Folk, Ester, and Troemel (Psychonomic Bulletin & Review 16:127–132, 2009) suggested that attentional capture can be blocked entirely when attention is already engaged in a different object. This conclusion relied on the finding that in a search for a known-color target in a rapid serial visual presentation stream, a peripheral distractor with the target color did not further impair target identification performance when a distractor also with the target color that appeared in the stream had already captured attention. In the present study, we argue that this conclusion is unwarranted, because the effects of the central and peripheral distractors could not be disentangled. In order to isolate the effect of the peripheral distractor, we introduced a distractor–target letter compatibility manipulation. Our results showed that the peripheral distractor summoned attention, irrespective of whether attention had just been engaged. We conclude that neither spatially focused attention nor attentional engagement is sufficient to prevent attentional capture.     

Anxiety, conscious awareness and change detection

Attentional scanning was studied in anxious and non-anxious participants, using a modified change detection paradigm. Participants detected changes in pairs of emotional scenes separated by two task irrelevant slides, which contained an emotionally valenced scene (the 'distractor scene') and a visual mask. In agreement with attentional control theory, change detection latencies were slower overall for anxious participants. Change detection in anxious, but not non-anxious, participants was influenced by the emotional valence and exposure duration of distractor scenes. When negative distractor scenes were presented at subliminal exposure durations, anxious participants detected changes more rapidly than when supraliminal negative scenes or subliminal positive scenes were presented. We propose that for anxious participants, subliminal presentation of emotionally negative distractor scenes stimulated attention into a dynamic state in the absence of attentional engagement. Presentation of the same scenes at longer exposure times was accompanied by conscious awareness, attentional engagement, and slower change detection.     

Task-based working memory guidance of visual attention

Previous research has established that holding a stimulus in working memory (WM) facilitates the deployment of visual attention to that stimulus relative to other stimuli. The present study examined whether maintaining a specific task in WM would also bias the allocation of attention to the stimuli associated with that task. Participants performed a speeded letter search task while simultaneously keeping in WM one of two task cues shown at the beginning of each trial. The results showed that task-based WM guidance of attention was modulated by response latencies. Whereas the participants with fast reaction times showed little influence of WM contents, the participants with slow reaction times took longer to respond when the letter target appeared in a distractor stimulus consistent with the task cue held in mind. A subsequent Stroop experiment found a larger Stroop interference effect from the participants in the slow group compared with those in the fast group, suggesting that the differential WM effect between the two groups may be associated with an individual's ability to inhibit task-irrelevant information. Taken together, these results expanded the realm of previous research and provided further evidence for a close link between attention and WM.     

Distraction and the auditory attentional blink

When two target stimuli (T1 and T2) are presented in close succession within a stimulus sequence, detection or discrimination performance for T2 is often impaired; this phenomenon is called the attentional blink (AB). Growing evidence suggests that the AB is present not only for visual, but also for auditory stimuli. Because sounds have a strong potential to attract attention when they are presented after longer silent intervals or in a sequence from which they stand out because of their rare or novel physical features, it seems possible that the involuntary and excessive allocation of attention to T1 (distraction) may contribute to the AB. By varying the saliency of T1, we showed that distraction does contribute to the auditory AB effect, but the contribution is short-lived: Only stimuli immediately following T1 are affected.     

Salience detection and attentional capture

There is an ongoing debate to what extent irrelevant salient information attracts an observer’s attention and is processed without the observer intending to do so. The present experiment investigated attentional capture of salient but irrelevant objects and compared target processing in target-and-distractor to target-only trials. Both form and color singletons were used and their target–distractor assignment was interchanged. Thus the general impact of the presence of a salient distractor on target processing could be separated from the impact of the specific target–distractor salience relation. Response latencies and event-related brain potentials (ERPs) were registered. Results showed a strong influence of the mere presence of an irrelevant distractor on target processing: both the visual N1 and the posterior N2 showed better attention focusing in target-only trials compared to target-and-distractor trials. Response times and N2pc results, on the other hand, showed evidence in favor of salience-specific attention allocation. N2pc results indicated that the distractor affected the allocation of attention in trials with form targets and color distractors but not in the opposite condition. Taken together, results showed a general impact of irrelevant salient singletons on search behavior when they were presented simultaneously with relevant singletons. The allocation of focal attention (as mirrored by the N2pc), however, was also influenced by the specific target–distractor salience relation.     

The effect of visual threat on spatial attention to touch

Viewing a threatening stimulus can bias visual attention toward that location. Such effects have typically been investigated only in the visual modality, despite the fact that many threatening stimuli are most dangerous when close to or in contact with the body. Recent multisensory research indicates that a neutral visual stimulus, such as a light flash, can lead to a tactile attention shift towards a nearby body part. Here, we investigated whether the threat value of a visual stimulus modulates its effect on attention to touch. Participants made speeded discrimination responses about tactile stimuli presented to one or other hand, preceded by a picture cue (snake, spider, flower or mushroom) presented close to the same or the opposite hand. Pictures of snakes led to a significantly greater tactile attentional facilitation effect than did non-threatening pictures of flowers and mushrooms. Furthermore, there was a correlation between self-reported fear of snakes and spiders and the magnitude of early facilitation following cues of that type. These findings demonstrate that the attentional bias towards threat extends to the tactile modality and indicate that perceived threat value can modulate the cross-modal effect that a visual cue has on attention to touch.     

The neural correlates of orienting to walking direction in 6‐month‐old infants: An ERP study

The ability to detect social signals represents a first step to enter our social world. Behavioral evidence has demonstrated that 6‐month‐old infants are able to orient their attention toward the position indicated by walking direction, showing faster orienting responses toward stimuli cued by the direction of motion than toward uncued stimuli. The present study investigated the neural mechanisms underpinning this attentional priming effect by using a spatial cueing paradigm and recording EEG (Geodesic System 128 channels) from 6‐month‐old infants. Infants were presented with a central point‐light walker followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target‐locked event‐related potential (ERP) responses and we used cortical source analysis to explore which brain regions gave rise to the ERP responses. The P1 component and saccade latencies toward the peripheral target were modulated by the congruency between the walking direction of the cue and the position of the target. Infants' saccade latencies were faster in response to targets appearing at congruent spatial locations. The P1 component was larger in response to congruent than to incongruent targets and a similar congruency effect was found with cortical source analysis in the parahippocampal gyrus and the anterior fusiform gyrus. Overall, these findings suggest that a type of biological motion like the one of a vertebrate walking on the legs can trigger covert orienting of attention in 6‐month‐old infants, enabling enhancement of neural activity related to visual processing of potentially relevant information as well as a facilitation of oculomotor responses to stimuli appearing at the attended location.     

社会行为的效价信息对注意捕获的影响：基于帮助和阻碍行为的探讨

采用学习-测验两任务范式, 通过3项实验探讨了社会行为的效价信息对注意捕获的影响。在学习阶段, 被试观看具有积极效价的帮助行为(某智能体帮助另一智能体爬山)和消极效价的阻碍行为(某智能体阻碍另一智能体爬山), 以及与各自运动特性匹配的无社会交互行为, 其目的为建立不同智能体颜色与社会行为效价信息的联结关系。在测验阶段, 则分别检验社会行为中的施动方(帮助者和阻碍者)颜色和受动方(被帮助者和被阻碍者)颜色的注意捕获效应。结果发现, 消极社会行为中施动方颜色和受动方颜色均更容易捕获注意, 而积极社会行为效价信息并没有改变联结特征值的注意捕获效应; 且相比于受动方, 与消极社会行为效价建立联结的施动方颜色的注意捕获效应更强。该结果提示, 存在消极社会行为效价驱动的注意捕获, 且消极的效价信息与卷入社会行为所有个体的特征建立联结, 但该联结中施动方物理特征具有更高的注意优先性。这一发现暗示, 声誉信息与对社会交互行为的整体表征可能综合作用于对社会交互事件的注意选择。     

Selective attention and interhemispheric response competition in the split-brain

The interfering effect of an unattended stimulus on processing of an attended item was studied in a single split-brain participant (LB) and in normal controls. Pairs of letters were presented to the left visual field (LVF), right visual field (RVF), or bilaterally. Participants attended to the rightmost letter while attempting to ignore the leftmost letter. Responses associated with the attended and to-be-ignored letters could be compatible or incompatible. Manual response latencies were generally slower on Response Incompatible compared to Response Compatible trials. Notably, LB displayed this effect on Bilateral trials, where target and distractor were presented to opposite visual fields. LB was unable to perform a same-different matching task with bilateral letter stimuli, but was able to name bilateral letters accurately. Hence, in the bilateral condition, the ability to cross-compare letters was dissociated from attentional interference and from letter naming. Implications of these findings are discussed.     

Salient stimuli capture attention and action

Reaction times in a visual search task increase when an irrelevant but salient stimulus is presented. Recently, the hypothesis that the increase in reaction times was due to attentional capture by the salient distractor has been disputed. We devised a task in which a search display was shown after observers had initiated a reaching movement toward a touch screen. In a display of vertical bars, observers had to touch the oblique target while ignoring a salient color singleton. Because the hand was moving when the display appeared, reach trajectories revealed the current selection for action. We observed that salient but irrelevant stimuli changed the reach trajectory at the same time as the target was selected, about 270 ms after movement onset. The change in direction was corrected after another 160 ms. In a second experiment, we compared manual selection of color and orientation targets and observed that selection occurred earlier for color than for orientation targets. Salient stimuli support faster selection than do less salient stimuli. Under the assumption that attentional selection for action and perception are based on a common mechanism, our results suggest that attention is indeed captured by salient stimuli.