注意瞬脱神经机制的研究

在很短的时间间隔内连续呈现两个目标刺激时,被试对第二个目标刺激的正确报告率显著下降,这种现象就是注意瞬脱.该文简述了注意瞬脱的概念、容量有限性等方面,尤其详细介绍了注意瞬脱神经机制研究的新进展,并对今后的研究提出展望.     

注意瞬脱效应的个体差异

注意瞬脱是指个体在对同一位置出现的多个刺激进行识别时, 如果第二个目标刺激出现在第一个目标刺激之后200~500 ms之间, 那么个体对第二个目标刺激的识别会显著降低的现象。研究表明, 注意瞬脱效应在健康人群中存在显著的个体差异, 主要表现在工作记忆、对分心刺激的抑制能力、意向聚焦、情绪状态和人格等方面。近年来, 注意瞬脱的个体差异也在多种神经疾病的临床研究中得到重视。未来的研究应更多关注注意瞬脱效应个体差异背后的神经机制以及应用研究。     

情绪T2对抗注意瞬脱：理解情绪优先加工的窗口

注意瞬脱是指从一系列干扰刺激中识别两个目标时,识别第一个目标(T1)往往会干扰之后200～500 ms内出现的第二个目标(T2)的识别,该现象反映了时间维度上的意识加工局限性。但研究发现,与中性T2相比,情绪T2可以在一定程度上对抗注意瞬脱。这为我们理解人类对情绪刺激的优先意识加工提供了一个观察窗口和研究手段。情绪T2对抗注意瞬脱受T1任务难度、T2任务类型和情绪预期等因素的影响,该过程涉及的脑区主要包括杏仁核、前扣带回和眶额皮层等区域;在时间进程上,情绪相比中性T2在认知加工的早期和晚期阶段都表现出增强的效应。情绪对抗注意瞬脱的认知神经机制可以用注意增强和巩固竞争假说来解释,即由杏仁核介导的情绪信息早期注意捕获是导致情绪对抗注意瞬脱的关键,而晚期的巩固过程受到任务要求等自上而下因素的影响。     

注意瞬脱的暂时性失控理论

在很短的时间间隔内连续呈现两个目标刺激时,被试对第二个目标刺激的正确报告率显著下降,这种现象就是注意瞬脱.本文在简要介绍注意瞬脱的瓶颈理论和注意资源耗竭理论的基础上,着重阐述注意瞬脱的暂时性失控理论及其面临的挑战,并对今后的研究提出展望.     

消极情绪刺激和焦虑状态对注意瞬脱的影响

当前研究采用经典的快速序列视觉呈现范式,以消极情绪图片和中性图片作为分心物,分别探讨了消极情绪刺激和不同焦虑状态对注意瞬脱的影响。结果显示:(1)负性图片为分心物引发显著的注意瞬脱现象。(2)当两目标之间的间隔(SOA)为200ms时,注意瞬脱现象最为明显,当SOA为600ms时,注意瞬脱现象依然存在。(3)与低特质焦虑个体相比,高特质焦虑个体的注意瞬脱现象更为明显。这些结果说明,负性加工偏向会加剧注意瞬脱现象,使得注意瞬脱现象持续更长的时间。高特质焦虑个体由于对负性刺激更敏感,导致了注意瞬脱更为明显。     

视觉注意瞬脱实验范式述评

视觉注意瞬脱是指在很短时间内(约500 ms)序列呈现两个目标刺激时,被试对第二个目标正确报告率显著下降的现象。近年来国外注意瞬脱实验研究渐成选择性注意研究领域的热点, 其实验范式疏理为两大类-- 单刺激序列RSVP范式和多刺激序列RSVP范式。综述对两类范式的诸多变式进行了分析与评估, 提出了影响注意瞬脱实验范式发展的四项实验因素和今后视觉注意瞬脱实验范式发展的五种趋势。     

注意瞬脱现象及其理论解释

注意瞬脱(attention blink,简称AB)现象是近年来注意研究的一个新聚焦点。文章简要介绍其发现过程,各国学者对其影响因素的初步探索,五种主要的理论解释和研究注意瞬脱现象的意义,并展望其研究之未来。     

注意瞬脱现象及其理论解释

注意瞬脱（attention blink, 简称AB）现象是近年来注意研究的一个新聚焦点。文章简要介绍其发现过程,各国学者对其影响因素的初步探索,五种主要的理论解释和研究注意瞬脱现象的意义,并展望其研究之未来。(     

注意瞬脱的瓶颈理论

综述了注意瞬脱的瓶颈理论的相关研究。主要包括：（1）高级中枢加工瓶颈形成的两阶段模型、中枢干扰理论、TLC假设和注意的延迟投入假设;（2）目标选择的控制瓶颈形成的输入过滤器与目标模板假说;（3）同时类型系列标记模型。最后从瓶颈理论在整个注意瞬脱理论中的片面性和注意瞬脱的瓶颈理论本身的不完善性两方面剖析了瓶颈理论的局限性     

注意捕获对注意瞬脱的消弱作用

本研究在经典的注意瞬脱研究范式中变化干扰刺激T2-1或目标刺激T2的颜色特征,探究由新异刺激特征引发的注意捕获对注意瞬脱的影响。结果发现,当改变T2-1或T2的颜色时,这些与任务无关的新异信息可以自下而上地引发注意捕获并减小注意瞬脱。注意瞬脱起因于有限注意资源的分配,资源的分配方式受注意捕获的自动调节。这为解决注意瞬脱到底是有限资源限制还是资源分配提供了新的实证和理论解释。     

Personality predicts temporal attention costs in the attentional blink paradigm

Accuracy for a second target is reduced when it is presented within 500 msec of a first target. This phenomenon is called the attentional blink (AB). A diffused attentional state (via positive affect or an additional task) has been shown to reduce the AB, whereas a focused attentional state (via negative affect) has been shown to increase the AB, purportedly by influencing the amount of attentional investment and flexibility. In the present study, individual differences in personality traits related to positive affect, negative affect, and cognitive flexibility were used to predict individual differences in AB magnitude. As hypothesized, greater extraversion and openness predicted smaller ABs. Greater openness also predicted higher overall target accuracy. Greater neuroticism predicted larger ABs and lower overall target accuracy. Conscientiousness, associated with less cognitive flexibility, predicted lower overall target accuracy. Personality may modulate the AB by influencing overinvestment via dispositional tendencies toward more or less stringent or capable cognitive control.     

Minds on the blink: The relationship between inattentional blindness and attentional blink

Failures of conscious visual awareness occur when specific task demands prevent an observer from detecting a stimulus that would otherwise be clearly visible. Two examples are inattentional blindness (IB) and attentional blink (AB). IB is the failure to detect an unexpected stimulus when attention is otherwise engaged. AB describes the inability to detect a second target that is presented within 180-500?ms of the first target. Previous research has suggested that similar cognitive processes underlie both IB and AB; however, they are distinct phenomena, and no evidence has directly linked the two. We tested the same group of observers on an IB task and an AB task. Consistent with our hypotheses, we found that "non-noticers" who failed to detect an unexpected stimulus in the IB task also demonstrated a larger AB effect. This suggests that some observers may be more generally susceptible to failures of conscious visual awareness, regardless of specific context.     

Memory search for the first target modulates the magnitude of the attentional blink

The resolution of temporal attention is limited in a manner that makes it difficult to identify two targets in short succession. This limitation produces the phenomenon known as the attentional blink (AB), in which processing of a first target (T1) impairs identification of a second target (T2). In the AB literature, there is broad agreement that increasing the time it takes to process T1 leads to a larger AB. One might, therefore, predict that increasing the number of possible T1 identities, or target set, from 1 to 16 would lead to a larger AB. We were surprised to find that this manipulation of T1 difficulty had no influence on AB magnitude. In subsequent experiments, we found that AB magnitude interacts with T1 processing time only under certain circumstances. Specifically, when the T1 task was either well masked or had to be completed online, we found a reliable interaction between AB magnitude and the target set size. When neither of these conditions was fulfilled, there was no interaction between target set size and the AB. Previous research found that when the target set changes from trial to trial, trials with more possible targets elicited a larger AB. In the present study, the target set is held constant, reducing the demands on working memory. Nevertheless, AB magnitude still interacts with target set size, as long as the T1 task cannot be processed offline. Thus, the act of searching memory delays subsequent processing, even when the role of working memory has been minimized.     

Relationships between attentional blink magnitude, RSVP target accuracy, and performance on other cognitive tasks

When two masked, to-be-attended targets are presented within approximately half a second of each other, performance on the second target (T2) suffers, relative to when the targets are presented further apart in time or when the first target (T1) can be ignored. This pattern of results is known as the attentional blink (AB). Typically, participants differ with respect to the magnitude of their AB and their overall target accuracy. Despite investigations as to what participant characteristics may influence AB performance (e.g., age, brain damage, or mood state), there has been no focused examination of whether individual differences in cognitive performance measures predict the magnitude of the AB or overall rapid serial visual presentation(RSVP) target accuracy. Our university studentparticipants performed single-target and dual-target RSVP tasks, as well as a selection of cognitive tasks that did not use RSVP presentations, with color, letter, digit, and object stimuli. Overall performance on each of the RSVP targets (T1, T2, and single target) was predicted by speeded manual and vocal identification times to isolated stimuli and by performance with other RSVP targets. However, the magnitude of the AB was predicted only by T1 accuracy, not by any other performance measures. The results suggest that individual differences in AB magnitude do not result from differences in effective RSVP target encoding and are not well explained by varied information-processing abilities.     

Individual differences in electrophysiological responses to performance feedback predict AB magnitude

The attentional blink (AB) is observed when report accuracy for a second target (T2) is reduced if T2 is presented within approximately 500 ms of a first target (T1), but accuracy is relatively unimpaired at longer T1–T2 separations. The AB is thought to represent a transient cost of attending to a target, and reliable individual differences have been observed in its magnitude. Some models of the AB have suggested that cognitive control contributes to production of the AB, such that greater cognitive control is associated with larger AB magnitudes. Performance-monitoring functions are thought to modulate the strength of cognitive control, and those functions are indexed by event-related potentials in response to both endogenous and exogenous performance evaluation. Here we examined whether individual differences in the amplitudes to internal and external response feedback predict individual AB magnitudes. We found that electrophysiological responses to externally provided performance feedback, measured in two different tasks, did predict individual differences in AB magnitude, such that greater feedback-related N2 amplitudes were associated with larger AB magnitudes, regardless of the valence of the feedback.     

Attentional disengagement in adults with Williams syndrome

Williams syndrome (WS) is a neurodevelopmental disorder characterized by a distinctive behavioral and cognitive profile, including widespread problems with attention. However, the specific nature of their attentional difficulties, such as inappropriate attentional allocation and/or poor attentional disengagement abilities, has yet to be elucidated. Furthermore, it is unknown if there is an underlying difficulty with the temporal dynamics of attention in WS or if their attentional difficulties are task-dependent, because previous studies have examined attention in established areas of deficit and atypicality (specifically, visuospatial and face processing). In this study, we examined attentional processing in 14 adults with WS (20–59 years) and 17 typically developing controls (19–39 years) using an attentional blink (AB) paradigm. The AB is the decreased ability to detect a second target when it is presented in close proximity to an initial target. Overall, adults with WS had an AB that was prolonged in duration, but no different in magnitude, compared with typically developing control participants. AB performance was not explained by IQ, working memory, or processing speed in either group. Thus, results suggest that the attention problems in WS are primarily due to general attentional disengagement difficulties rather than inappropriate attentional allocation.     

Simultaneous and preceding sounds enhance rapid visual targets: Evidence from the attentional blink

Presenting two targets in a rapid visual stream will frequently result in the second target (T2) being missed when presented shortly after the first target (T1). This so-called attentional blink (AB) phenomenon can be reduced by various experimental manipulations. This study investigated the effect of combining T2 with a non-specific sound, played either simultaneously with T2 or preceding T2 by a fixed latency. The reliability of the observed effects and their correlation with potential predictors were studied. The tone significantly improved T2 identification rates regardless of tone condition and of the delay between targets, suggesting that the crossmodal facilitation of T2 identification is not limited to visual-perceptual enhancement. For the simultaneous condition, an additional time-on-task effect was observed in form of a reduction of the AB that occurred within an experimental session. Thus, audition-driven enhancement of visual perception may need some time for its full potential to evolve. Split-half and test-retest reliability were found consistently only for a condition without additional sound. AB magnitude obtained in this condition was related to AB magnitudes obtained in both sound conditions. Self-reported distractibility and performance in tests of divided attention and of cognitive flexibility correlated with the AB magnitudes of a subset but never all conditions under study. Reliability and correlation results suggest that not only dispositional abilities but also state factors exert an influence on AB magnitude. These findings extend earlier work on audition-driven enhancement of target identification in the AB and on the reliability and behavioural correlates of the AB.     

Do emotion-induced blindness and the attentional blink share underlying mechanisms? An event-related potential study of emotionally-arousing words

When two targets are presented within approximately 500 ms of each other in the context of rapid serial visual presentation (RSVP), participants’ ability to report the second target is reduced compared to when the targets are presented further apart in time. This phenomenon is known as the attentional blink (AB). The AB is increased in magnitude when the first target is emotionally arousing. Emotionally arousing stimuli can also capture attention and create an AB-like effect even when these stimuli are presented as to-be-ignored distractor items in a single-target RSVP task. This phenomenon is known as emotion-induced blindness (EIB). The phenomenological similarity in the behavioral results associated with the AB with an emotional T1 and EIB suggest that these effects may result from similar underlying mechanisms – a hypothesis that we tested using event-related electrical brain potentials (ERPs). Behavioral results replicated those reported previously, demonstrating an enhanced AB following an emotionally arousing target and a clear EIB effect. In both paradigms highly arousing taboo/sexual words resulted in an increased early posterior negativity (EPN) component that has been suggested to represent early semantic activation and selection for further processing in working memory. In both paradigms taboo/sexual words also produced an increased late positive potential (LPP) component that has been suggested to represent consolidation of a stimulus in working memory. Therefore, ERP results provide evidence that the EIB and emotion-enhanced AB effects share a common underlying mechanism.     

Attentional bias toward emotional stimuli in accidentally injured Chinese patients with different posttraumatic growth levels

Extensive evidence has been obtained that supports an association between an attentional bias (AB) toward negative stimuli and vulnerability to stress-related psychopathology, little is known regarding the characteristics of individual AB in different posttraumatic growth (PTG) levels. The current study used a modified dot-probe task to investigate if individual differences in AB towards either positive or negative emotional stimuli, are related to self-reported PTG. A sample of 202 patients completed the experiment. Patients with low levels of PTG did not exhibit AB toward negative or positive stimuli, patients with medium levels of PTG had difficulty disengaging attention from negative stimuli, patients with high levels of PTG had difficulty disengaging attention from positive stimuli. And the AB towards positive stimuli was only predictive for PTG. An implication of this finding is that there are different characteristics of implicit cognitive processing in patients with different levels of PTG, suggesting the necessity of psychological intervention on the accidentally injured patients.