“鸡尾酒会”环境中的知觉线索的去掩蔽作用

在有多人同时说话的嘈杂环境中,为什么具有正常听力的人能在一定的程度上听懂目标语句？研究这个著名的“鸡尾酒会”问题的一个新进展是将干扰言语的作用区分出了能量掩蔽和信息掩蔽两种成分。与发生在外周系统的能量掩蔽不同,信息掩蔽发生在心理层次并受到认知过程的调节。因此,主观空间分离、与目标语句节奏相关的视觉信号以及对目标语句某些特征的熟悉程度等知觉线索都具有去掩蔽作用。考察可减少信息掩蔽的知觉线索的交互作用及其高级认知调节是今后重要的研究内容     

客体替代掩蔽:视觉后向掩蔽研究的新进展

传统的知觉实验通常采用视觉后向掩蔽在网膜水平上干扰对目标刺激的加工,主要有模式掩蔽和偏对比掩蔽两种形式.近年来客体替代掩蔽(简称OSM)的实验研究表明,围绕目标刺激呈现四个点也可导致目标刺激的可见性下降.OSM发生在客体表征水平上,它既是值得研究的掩蔽现象,也可以作为一种新的研究范式.本文介绍OSM的心理物理学和计算模型研究,并指出它对于认知科学的重要意义.     

基于双眼视差的立体视觉去掩蔽效应

基于双眼视差的立体视觉不改变目标与掩蔽刺激之间的信噪比, 但能使不同的刺激被知觉在不同的深度位置上以降低目标信号所受到的掩蔽作用。本综述在总结前人双眼去掩蔽研究的基础上, 强调深度维度上的视觉注意在这种主观空间分离去掩蔽过程中所起的重要作用, 并介绍了双眼去掩蔽在现代科技领域中的典型性应用。最后, 结合听觉主观空间分离去掩蔽的研究进展, 本综述认为主观空间分离去掩蔽是大脑处理复杂刺激场景的一个基本功能。     

视觉掩蔽可基于知觉到的客体位置

利用flash—lag效应分离视觉掩蔽中客体的物理位置和知觉位置,以探讨掩蔽效应是否基于知觉到的客体位置。实验中掩蔽刺激做圆周运动,到某一位置时,目标刺激短时呈现,要求被试判断目标刺激（缺角菱形）的缺角方向。通过操作目标呈现时二者之间的相对位置,发现当二者物理位置不重合而知觉位置重合时掩蔽效应最大。该结果表明,视觉掩蔽可基于知觉到的客体位置。     

实物形状的知觉相似性对视觉隐喻加工的影响

视觉隐喻是众多研究者比较关注的领域, 当前多以物体简笔画、漫画及广告等方面的研究为主, 但对与生活密切相关的实物的视觉隐喻研究甚少。因此研究采用掩蔽启动范式、李克特9点量表及语音生成等研究方法, 在物体概念类型(概念相同、概念相异)及形状类型(形状相似、形状相异)条件下, 针对实物图片的形状知觉相似性是否对视觉隐喻加工产生影响进行探讨。结果发现无论物体概念是否相同, 形状相似性对个体的物体识别具有“促进”作用, 并有利于视觉隐喻加工; 在物体识别中, 当两个物体概念不同时, 个体会试图建立一个特设类别来对形状相似的物体进行归类, 从而实现了视觉隐喻的加工。因此研究进一步证明了实物形状的知觉相似性有利于视觉隐喻的加工。     

听觉信息掩蔽的亚成分：基于行为和脑成像研究的证明

听觉掩蔽的机制是解决嘈杂声学环境下对特定目标声音进行加工, 即“鸡尾酒会”问题的关键。听觉掩蔽可以分为能量掩蔽和信息掩蔽两种类型。前者是因为目标和掩蔽声音在听觉外周在时间和频率上的重叠所造成的, 而后者被认为是掩蔽声音在听觉中枢和目标声音竞争加工资源所造成的。长久以来, 信息掩蔽一直被当作一种单一成分的现象, 这一概念框架已经成为制约对其机制进行深入研究的一个瓶颈。信息掩蔽中至少包含有知觉信息掩蔽和认知信息掩蔽两种亚成分, 它们源于不同的中枢机制。多个说话人声音掩蔽的条件下, 总体掩蔽量是能量掩蔽、知觉信息掩蔽和认知信息掩蔽等成分总和的结果。操纵掩蔽和目标声音的知觉空间分离、掩蔽声音的可懂度以及掩蔽和目标声音的知觉相似度, 可以实现对两种信息掩蔽亚成分的双重分离。应用功能性核磁共振成像技术可以发现两者有不同的神经机制。     

负相容效应理论与研究

负相容效应指在掩蔽的箭头启动项后呈现箭头目标项时,对与启动项方向不一致的目标项反应更快。综述了负相容效应的主要理论及研究,包括自我抑制理论和知觉交互作用理论等。讨论了目前负相容效应研究面临的困难与挑战,包括实验控制条件的限制、掩蔽项与启动项特征的相似性以及应用认知神经研究方法进行研究的困难,并从理论更新与整合、神经基础、生态学意义视角等几方面对未来的研究做出展望。     

知觉与行为的分离在视错觉研究中的验证

知觉与行为的分离是指人的视觉对物体的知觉与对行为的控制属于两个不同的系统。最早人们从临床病例中发现存在知觉与行为的分离,以后Aglioti等利用铁钦纳错觉实验证实正常人中也存在这一分离现象。一些研究者将两者的分离看作是两个不同视觉皮层通路（腹侧知觉系统和背侧视觉运动系统）的结果。围绕这一分离现象的实验和假说引发了不少的争论。该文回顾了十年来利用错觉实验所做的众多验证性研究,分析了支持和否定分离现象存在的各类证据,对一些重要结果和观点进行了总结,并由此提出了自己的看法。     

自然物体分类的ERP研究

对事物进行分类的能力是人类的一种基本认知功能。该文主要就近年来自然物体分类的事件相关电位（ERP）研究情况进行综述。首先介绍与自然物体分类有关的ERP早晚期成分;接着讨论了快速视觉分类的加工机制,认为前馈机制在这种复杂分类任务的视觉加工过程中起重要作用;最后详细介绍了两个分离的视觉加工机制,认为自然物体的视觉分类在不同时程涉及不同机制：即首先是任务无关的早期知觉加工过程,其次是任务相关的、类别无关的加工机制,与被试的决策有关。也讨论了这两个分离的加工过程涉及的神经基础。     

视觉短时记忆与视知觉的信息整合

与知觉整合和跨眼跳的信息整合一样,视觉短时记忆与视知觉的信息整合也是人们加工并保持整体性场景知觉的重要前提条件。近年来研究者们使用空白单元格定位任务进行了一些研究,试图寻求视觉短时记忆与视知觉信息整合的实验证据并探讨其整合机制。该文对已有的相关实验范式、实验证据和整合机制进行了介绍并加以分析,并指出未来研究可以在行为数据的基础上结合眼动和脑成像的数据寻求汇聚性证据     

What's new in visual masking?

A brief display that is clearly visible when shown alone can be rendered invisible by the subsequent presentation of a second visual stimulus. Several recently described backward masking effects are not predicted by current theories of visual masking, including masking by four small dots that surround (but do not touch) a target object and masking by a surrounding object that remains on display after the target object has been turned off. A crucial factor in both of these effects is attention: almost no masking occurs if attention can be rapidly focused on the target, whereas powerful masking ensues if attention directed at the target is delayed. A new theory of visual masking, inspired by developments in neuroscience, can account for these effects, as well as more traditional masking effects. In addition, the new theory sheds light on related research, such as the attentional blink, inattentional blindness and change blindness.     

Temporal buffering and visual capacity: The time course of object formation underlies capacity limits in visual cognition

Capacity limits are a hallmark of visual cognition. The upper boundary of our ability to individuate and remember objects is well known but—despite its central role in visual information processing—not well understood. Here, we investigated the role of temporal limits in the perceptual processes of forming “object files.” Specifically, we examined the two fundamental mechanisms of object file formation—individuation and identification—by selectively interfering with visual processing by using forward and backward masking with variable stimulus onset asynchronies. While target detection was almost unaffected by these two types of masking, they showed distinct effects on the two different stages of object formation. Forward “integration” masking selectively impaired object individuation, whereas backward “interruption” masking only affected identification and the consolidation of information into visual working memory. We therefore conclude that the inherent temporal dynamics of visual information processing are an essential component in creating the capacity limits in object individuation and visual working memory.     

Substituting objects from consciousness: A review of object substitution masking

Object substitution masking (OSM) occurs when a sparse (e.g., four-dot), temporally trailing mask obscures the visibility of a briefly presented target. Here, we review theories of OSM: those that propose that OSM reflects the interplay between feedforward and feedback/reentrant neural processes, those that predict that feedforward processing alone gives rise to the phenomenon, and theories that focus on cognitive explanations, such as object updating. We discuss how each of these theories accommodates key findings from the OSM literature. In addition, we examine the relationship between OSM and other visual-cognitive phenomena, including object correspondence through occlusion, change blindness, metacontrast masking, backward masking, and visual short-term memory. Finally, we examine the level of processing at which OSM impairs target perception. Collectively, OSM appears to reflect the conditions under which the brain confuses two visual events for one when they are encoded with low spatiotemporal resolution, due to processing resources being otherwise occupied.     

A comparison of masking by visual and transcranial magnetic stimulation: implications for the study of conscious and unconscious visual processing

Visual stimuli as well as transcranial magnetic stimulation (TMS) can be used: (1) to suppress the visibility of a target and (2) to recover the visibility of a target that has been suppressed by another mask. Both types of stimulation thus provide useful methods for studying the microgenesis of object perception. We first review evidence of similarities between the processes by which a TMS mask and a visual mask can either suppress the visibility of targets or recover such suppressed visibility. However, we then also point out a significant difference that has important implications for the study of the time course of unconscious and conscious visual information processing and for theoretical accounts of the processes involved. We present evidence and arguments showing: (a) that visual masking techniques, by revealing more detailed aspects of target masking and target recovery, support a theoretical approach to visual masking and visual perception that must take into account activities in two separate neural channels or processing streams and, as a corollary, (b) that at the current stage of methodological sophistication visual masks, by acting in more highly specifiable ways on these pathways, provide information about the microgenesis of form perception not available with TMS masks.     

ERP evidence for temporal independence of set size and object updating in object substitution masking

To keep track of dynamically changing objects in one’s environment, it is necessary to individuate them from other objects, both temporally and spatially. Spatially, objects can be selected from nearby distractors using selective attention. Temporally, object updating processes incorporate new information into existing representations over time. Both of these processes have been implicated in a type of visual masking called object-substitution masking (OSM). Previous studies have found that the number of distractors (impacting selective attention) interacts with the strength of OSM. However, it has been suggested that this interaction is an artifact of ceiling performance at low set sizes, rather than necessitating a failure of attention during masking. Using event-related potentials (ERPs), we examined whether set size and masking interact as measured by markers of selective attention (N2pc) and visual working memory consolidation/maintenance (SPCN). Set size was found to affect the N2pc (200–350 ms) and late SPCN (500–650 ms), reflecting increased demands on selective attention and unnecessary storage respectively. An early window of the SPCN (350–500 ms) was affected by masking, suggesting that OSM influences object consolidation processes in this window, independent of the number of distractors. Overall, it was found that selective attention and visual awareness are dissociable neural processes in OSM, and that they are independently affected by set size and masking manipulations. Moreover, we found that the early SPCN may reflect disruptions to object consolidation, potentially revealing a neural mechanism supporting an object individuation-through-updating account of OSM.     

Deeper attentional masking by lateral objects in children with autism

Autism spectrum disorder (ASD) is often associated with a detail-oriented perception and overselective attention in visual tasks, such as visual search and crowding. These results were obtained manipulating exclusively the spatial properties of the stimuli: few is known about the spatio-temporal dynamics of visual processing in ASD. In this study we employed an attentional masking (AM) paradigm comparing children with ASD and IQ-matched typically developing (TD) controls. The AM effect refers to an impaired identification of a target followed by a competitive masking object at different proximities in space and time. We found that ASD and TD groups did not differ in the AM effect provoked by the competitive object displayed in the same position of the target. In contrast, children with ASD showed a deeper and prolonged interference than the TD group when the masking object was displayed in the lateral position. These psychophysical results suggest that the inefficient attentional selection in ASD depends on the spatio-temporal interaction between competitive visual objects. These evidence are discussed in the light of the ASD altered neural connectivity hypothesis and the reentrant theory of perception.     

Variations in backward masking with different masking stimuli: I. Local interaction versus attentional switch

The types of stimuli used as targets and masks considerably change the masking functions in a way that requires us to abandon any single mechanism of masking as the sole explanation of backward masking. In the first of two reports in which the problem of the mask-dependence of masking is addressed, we explore the role of the relative spatial positioning of targets and masks in order to differentiate between local interaction and attentional models. If single letters were masked by double-letter masks then the relative spatial arrangement of the letters, which was changed in order to vary the involvement of metacontrast-like processes, had an effect at shorter SOAs, but not at longer SOAs where strong masking still persisted. This poses difficulties for proposing local contour interaction as the main mechanism of masking. Similarly, crowding effects alone cannot explain the results. Backward masking also involves attention being directed to working-memory processing of the succeeding object while abandoning the preceding object.     

The effect of smoking on sensory and attentional masking

This study examined the influence of smoking on low-level sensory and higher level visual cognitive abilities. Three groups (nonsmokers, deprived smokers, and nondeprived smokers) of 22 observers were tested using a visual target discrimination task. To assess sensory and visual cognitive differences, a masking task developed by Enns and Di Lollo (1997) was used. In the task, the target was masked by either a contour mask (contour masking) or an object mask (attentional masking by object substitution). The strongest masking effects were found in the group of nondeprived smokers, for both sensory and attentional masking. This pattern of results as well as results in the deprived smokers indicated changes in transient visual processing channels due to the acute actions of nicotine, not mediated by withdrawal relief.     

Visual masking during the attentional blink: tests of the object substitution hypothesis

When 2 masked targets are presented in a rapid sequence, correct identification of the 1st hinders identification of the 2nd. Visual masking of the 2nd target plays a critical role during this 2nd-target deficit, or "attentional blink" (AB). The object substitution hypothesis (B. Giesbrecht & V. Di Lollo, 1998) predicts that late-stage visual processes involved in object substitution mediate masking of the 2nd target during AB, whereby stronger masking should produce a more severe deficit. Six experiments are presented, together testing this hypothesis. Although masking by object substitution was observed, it did not interact with the AB. An alternative hypothesis is proposed stating that mostly early-stage visual processes mediate the masking effects that are critical to the AB.     

Selective storage and maintenance of an object’s features in visual working memory

It has been shown that we have a highly capacity-limited representational space with which to store objects in visual working memory. However, most objects are composed of multiple feature attributes, and it is unknown whether observers can voluntarily store a single attribute of an object without necessarily storing all of its remaining features. In this study, we used a masking paradigm to measure the efficiency of encoding, and neurophysiological recordings to directly measure visual working memory maintenance while subjects viewed multifeature objects and were required to remember only a single feature or all of the features of the objects. We found that measures of both encoding and maintenance varied systematically as a function of which object features were task relevant. These experiments show that individuals can control which features of an object are selectively stored in working memory.