平滑运动条件下的图形颜色及形状加工特性的研究

本研究对在运动图形识别过程中,有关图形的不同特征（颜色、形状等）的加工特性、方向性效应以及不同空间位置（或时间间隔）对图形识别的影响了探讨。结果发现,视觉系统在运动信息加工时,对目标的不同特征的加工存在不均衡性,加工的难度有差异。颜色的加工难度要比形状的加工难度小。视觉系统对不同运动方向上的图形匹配反应特性也存在差异,图形匹配过程受时间或距离因素的影响,匹配的反应时随着两个比较图形之间的空间距离的增加而减少。     

认知控制对基于位置和颜色返回抑制的影响

采用带颜色的字母为靶刺激.通过操纵被试任务.考察辨别任务中认知控制对基于位置和颜色IoR的影响.结果发现:要求被试辨别带颜色的字母,没有出现基于颜色的IoR;要求被试辨别颜色.出现了基于颜色的IoR.说明.自上而下的认知控制是基于颜色IoR产生的关键因素之一.其内在机制可用抑制模型和注意资源分配理论从不同角度解释.同时,两种任务均未要求被试辨别靶刺激的位置,却都出现了基于位置的IoR,验证了Russell"注意可能存在对位置信息自动加工"的假说.     

沃尔夫假说的新证据:范畴内和范畴间颜色辨别难度相同时语言范畴也会影响注意前颜色知觉

该研究探讨了当范畴内和范畴间颜色的辨别难度相同时,语言范畴是否会影响注意前颜色知觉。实验中,采用渐变且相邻者差别阈限数相当的A、B、C、D四种颜色（前两者为绿色,后两者为蓝色）为刺激材料,并让被试接受视觉Oddball脑电测试。脑电测试分视野给被试呈现标准刺激,以及与标准刺激属同一语言范畴（即颜色词绿色或蓝色）或不同语言范畴的偏差刺激。结果发现：在左视野呈现时,范畴内偏差刺激比范畴间偏差刺激诱发了边缘显著更大的视觉失匹配负波（vMMN）,在右视野呈现时,两类偏差刺激诱发的vMMN无显著差异;范畴内偏差刺激在不同视野呈现时诱发的vMMN无显著差异,范畴间偏差刺激则在右视野呈现时诱发了显著更大的vMMN。这一结果表明,当范畴内和范畴间颜色的辨别难度相同时,语言范畴也会影响早期的、注意前颜色知觉,支持了沃尔夫假说。     

异同判断中“快同效应”的大脑机制：一项ERP研究

采用高密度的事件相关电位（ERPs）技术,记录分析了大学生被试在执行异同判断任务[包括不同颜色刺激对（DC）,不同形状刺激对（DS）和相同刺激对（Same）]时的脑内时程动态变化。行为结果表明,“同”反应的确显著快于“异”反应,表现出明显的快同效应。ERP结果显示：在280-320 ms内,DS和DC条件均比Same条件诱发一个更负的N2成分。偶极子溯源分析表明,DC和DS条件下,N2可能起源于大脑的前扣带皮层（ACC）,可能与“异”反应早期不一致信息（颜色或形状）的认知监控和调节有关;反之Same条件下,N2成分可能起源于楔前叶,主要反映了“同”反应早期知觉识别中整体特征比较加工的过程（同一性指示器）。另外,在450 ms左右, DC和DS比Same条件均诱发了一个更负的P3成分,可能反映了对刺激局部特征的比较和识别（慢速比较器）,并与选择性注意和资源分配等高级认知活动有关;并且,Same条件下P3成分的潜伏期更短,与行为结果一致。以上研究结果表明,异同判断中“同”反应和“异”反应可能有着不同的比较通道和大脑机制,支持双过程模型理论;同时表明,慢速比较器和同一性指示器可能是序列加工的。     

在亮度对比和颜色对比下立体视知觉的定量研究

研究了在亮度对比与等亮度颜色对比的条件下,受试者分辨随机点阵立体图对的立体视敏度（最小视差）．结果表明：（１）在亮度对比条件下,立体视敏度随对比度的增加而增加,１０％的对比度即可引起立体视知觉,对比度大于３０％时达到饱和;（２）在亮度对比与等亮度颜色对比两种不同的条件下,受试者的立体视敏度不存在有统计学意义的差异;（３）当双眼分别接受不同颜色的等亮度立体图刺激时,与亮度对比条件相比,受试者的立体视敏度无明显差异;（４）当受试者双眼分别接受由亮度对比和颜色对比形成的立体图刺激时,只有当颜色对比图中图形与背景间的对比度超过等亮度值３８％以上时,才能形成立体视知觉．以上结果提示,大、小细胞系统（包括斑点系统与斑点间系统）均参与立体视知觉信息的传递．     

习得的语言范畴对注意前颜色范畴知觉的影响:一项ERP研究

该研究探讨了语言范畴对注意前颜色知觉的影响依赖于语言范畴与颜色长期联结还是其即时分类颜色,同时检验了习得的语言范畴是否能因果性地改变早期颜色知觉机能。采用G1、G2、B1、B2（前两者为绿色,后两者为蓝色）4种连续变化的颜色为材料。学习组和分类组被试分别接受6次和1次色词与颜色重组训练,学习4种颜色不同的新名称,并在之后均接受视觉Oddball脑电测试。训练结果显示：学习组稳定地习得了4种颜色的新名称,分类组能以新名称将颜色分为4类。测试结果显示：学习组的颜色知觉中出现了与习得语言范畴对应的偏侧化注意前颜色范畴知觉,分类组的颜色知觉中未出现与颜色分类对应的偏侧化注意前颜色范畴知觉。研究结果表明：语言范畴对注意前颜色知觉的影响依赖于语言范畴与颜色长期联结而非其即时分类颜色;习得的语言范畴能引起偏侧化注意前颜色范畴知觉,提示习得的语言范畴能因果性地改变早期颜色知觉机能。     

复合运动刺激视觉追踪的初步研究

本实验采用多目标追踪和复合刺激研究范式,将注意追踪和知觉的整体优先性两个研究领域中存在的知觉组织规律相结合,对单一和多个复合刺激进行注意追踪研究.结果表明:在单一或多个复合刺激追踪过程中,同样遵循静态知觉组织原则;不同知觉组织形式对知觉加工有不同的影响,突出的颜色变化可以促进知觉组织加工.     

从知觉负载理论来理解选择性注意

知觉负载理论被认为解决了选择性注意研究的早选择和晚选择观点之争。当前任务对注意资源的耗用程度决定了与任务无关的干扰刺激得到多少加工,从而导致在低知觉负载下,注意资源自动溢出去加工干扰刺激（晚选择）,而在高知觉负载下,注意资源被当前任务耗尽而无法加工干扰刺激（早选择）。知觉负载理论提出后,研究者进行了一系列研究。一部分工作专注于知觉负载对选择性注意的调节作用;另外一些工作则关注其他认知过程如何影响注意资源的分配,其中知觉负载与工作记忆负载的关系是当前关注重点。     

不同类型材料混合呈现对SNARC效应的影响

采用刺激分类范式,要求被试判断呈现刺激的性质(实验一和实验三)或颜色(实验二),旨在考察随机呈现不同类型刺激材料对数字和字母SNARC效应的影响以及不同类型刺激材料加工中是否存在刺激—反应相容性效应。结果发现:(1)数字和字母性质和颜色分类任务中均未出现数字SNARC效应和字母SNARC效应。(2)数字和字母的性质和颜色分类任务中,左手对字母的反应更快,右手对数字的反应更快。数字和汉字性质分类时,左手对汉字反应更快,右手对数字反应更快,不同类型刺激分类时出现刺激—反应相客性效应。(3)本研究发现不同类型刺激分类加工中存在刺激—反应相容性效应,这种效应可以被自动激活,并具有一定的普遍性。不同类型刺激分类中的刺激—反应相容性效应对SNARC效应具有抑制作用。     

知觉或记忆条件下对连续变化刺激的相似判断

控制不同材料(图形和字母)的大小、位置和长宽比连续变化,在标准和待判断刺激同时(知觉任务)或相继呈现(记忆任务)两种条件下进行相似判断的实验研究。结论为(1)任务方式对图形的相似判断有非常显著的影响;(2)知觉任务中相似判断的反应时非常显著地长于记忆任务中的反应时;(3)对材料各种特征的相似判断和加工速度差异非常显著．某些特征在相似表征中有较重要的作用。     

Subitizing requires attention

While counting objects is typically a slow, serial process, enumerating about four or fewer objects has been considered to be a relatively effortless, parallel, and even preattentive process often referred to as subitizing. However, by combining a subitizing task with an attentional blink task, we show that subitizing is systematically affected by a closely preceding letter identification task. Vice versa, letter identification is also affected by a closely preceding subitizing task. Importantly, performance not only depended on the time between the two tasks, but also on the number of to-be-enumerated dots, even though this number fell within the subitizing range. The results imply that the processes underlying subitizing require attentional resources, suggesting that they are either serial in nature, or parallel, with capacity limited by the overall resources available.     

The attentional blink is governed by a temporary loss of control

Identification of the second of two brief targets is impaired at intertarget lags of less than about 500 msec. We compared two accounts of thisattentional blink (AB) by manipulating the number of digit distractors—and hence the lag—inserted among three letter targets in a rapid serial visual presentation stream of digit distractors. On the resource-depletion hypothesis, longer lags provide more time for processing the leading target, thus releasing resources for the trailing target. On the temporary-loss-of-control (TLC) hypothesis, intervening distractors disrupt the current attentional set, producing a trailing-target deficit. Identification accuracy for trailing targets was unimpaired not only at lag 1 (conventional lag 1 sparing) but also at later lags, if preceded by another target. The results supported the TLC hypothesis but not the resource-depletion hypothesis. We conclude that the AB is caused by a disruption in attentional set when a distractor is presented while the central executive is busy processing a leading target.     

Transient suppression of processing during rapid serial visual presentation: Acquired distinctiveness of probes modulates the attentional blink

The attentional blink is revealed in studies of rapid serial visual processing, in which observers view a stream of letters presented sequentially at the same location in a visual display. Reporting the identity of a specially marked letter (the target) amidst distractors causes a transient loss of accuracy for detection of another prespecified symbol (the probe). In two experiments, observers viewed lists of letters, identified a randomly selected letter as a target, and detected the presence of a probe from a different category (a digit or a Greek letter). After several days of training, probe detection following a target had improved markedly. Posttarget probe detection was again impaired when the distractor set included members of the probe set. These results are compatible with an explanation of the attentional blink as an act of suppression aimed at the current set of distractors, but additional mechanisms are needed to account for the effects of training.     

Does attention affect visual feature integration?

Two questions are investigated in this work: first, whether the integration of color and shape information is affected by attending to the stimulus location, and second, whether attending to a stimulus location enhances the perceptual representation of the stimulus or merely affects decision processes. In three experiments, subjects were briefly presented with colored letters. On most trials, subjects were precued to the stimulus location (valid cue); on some trials, a nonstimulus location was cued (invalid cue). Subjects were less likely to incorrectly combine colors and letter shapes following a valid cue. The attentional facilitation afforded by the cue was not limited to feature integration but also affected the registration of features. However, when the amount of feature information was strictly controlled, attention still affected feature integration. The results indicate that orienting attention to the location of the cue affects the quality of the perceptual representation for features and their integration.     

Rapid processing of letters,digits and symbols: what purely visual‐attentional deficit in developmental dyslexia?

Visual‐attentional theories of dyslexia predict deficits for dyslexic children not only for the perception of letter strings but also for non‐alphanumeric symbol strings. This prediction was tested in a two‐alternative forced‐choice paradigm with letters, digits, and symbols. Children with dyslexia showed significant deficits for letter and digit strings but not for symbol strings. This finding is difficult to explain for visual‐attentional theories of dyslexia which postulate identical deficits for letters, digits and symbols. Moreover, dyslexics showed normal W‐shaped serial position functions for letter and digit strings, which suggests that their deficit is not due to an abnormally small attentional window. Finally, the size of the deficit was identical for letters and digits, which suggests that poor letter perception is not just a consequence of the lack of reading. Together then, our results show that symbols that map onto phonological codes are impaired (i.e. letters and digits), whereas symbols that do not map onto phonological codes are not impaired. This dissociation suggests that impaired symbol‐sound mapping rather than impaired visual‐attentional processing is the key to understanding dyslexia.     

The time course of attentional capture under dual-task conditions

Several recent studies have shown that attentional capture is not an automatic process. For example, abrupt peripheral onsets do not affect the processing of targets presented subsequently at that location when participants have to concurrently perform a perceptually demanding task elsewhere. This result leaves open the question of whether peripheral onsets lose their effectiveness in capturing attention or whether, instead, the performance of a perceptually demanding task entails a faster disengagement of attention from the cued location. Here, we measured exogenous spatial attentional-orienting effects either while participants performed a concurrent perceptually demanding central-monitoring task (a rapid serial visual presentation of letters for a to-be-detected digit target; Experiments 1 and 2) or in isolation (the baseline condition in Experiment 2). The results showed that peripheral onsets captured participants' attention at both the 80- and 190-ms stimulus onset asynchronies (SOAs) in the baseline condition. Crucially, however, during concurrent central monitoring, peripheral onsets were effective in capturing attention only at an 80-ms SOA, while the orienting effect disappeared as soon as a changing letter drew participants' attention back to the central stream (at an SOA of 190 ms). These findings demonstrate that task-irrelevant abrupt onsets cannot be entirely overridden by top-down attentional control, although attentional capture effects are dramatically reduced by an ongoing perceptually demanding task.     

Types and tokens in visual letter perception

Five experiments demonstrate that in briefly presented displays, subjects have difficulty distinguishing repeated instances of a letter or digit (multiple tokens of the same type). When subjects were asked to estimate the numerosity of a display, reports were lower for displays containing repeated letters, for example, DDDD, than for displays containing distinct letters, for example, NRVT. This homogeneity effect depends on the common visual form of adjacent letters. A distinct homogeneity effect, one that depends on the repetition of abstract letter identities, was also found: When subjects were asked to report the number of As and Es in a display, performance was poorer on displays containing two instances of a target letter, one appearing in uppercase and the other in lowercase, than on displays containing one of each target letter. This effect must be due to the repetition of identities, because visual form is not repeated in these mixed-case displays. Further experiments showed that this effect was not influenced by the context surrounding the target letters, and that it can be tied to limitations in attentional processing. The results are interpreted in terms of a model in which parallel encoding processes are capable of automatically analyzing information from several regions of the visual field simultaneously, but fail to accurately encode location information. The resulting representation is thus insufficient to distinguish one token from another because two tokens of a given type differ only in location. However, with serial attentional processing multiple tokens can be kept distinct, pointing to yet another limit on the ability to process visual information in parallel.     

注意捕获效应受知觉负载及目标与干扰项距离的共同影响

研究考察了无关干扰项引发的注意捕获效应如何受到任务知觉负载以及目标与干扰项距离的共同影响。被试在视觉搜索集中搜索目标并做辨别反应。通过控制搜索集的大小来控制任务知觉负载, 同时在搜索集中存在一个用颜色标定的无关干扰项(奇异项), 该奇异项与当前的搜索目标存在一致、中性或不一致的关系, 该奇异项的位置与当前目标相邻或相距较远。结果发现, 被试在低负载条件下出现显著的干扰效应(不一致条件的反应时减中性条件的反应时), 而在高负载条件下干扰效应减小。此外, 在高负载条件下, 当目标与干扰项相距较近时没有出现干扰效应, 而当目标与干扰项相距较远时存在显著的干扰效应。干扰效应受到任务知觉负载和目标与无关干扰项距离的共同影响。这些结果说明, 与任务无关的刺激是否捕获注意取决于当前任务总体上是否存在可用的剩余注意资源, 也受到其周围临近区域的局部注意资源是否充足的影响。     

Familiarity, redundancy, and the spatial control of visual attention

Highly familiar letter sequences (English words) in noncued portions of a tachistoscopic display were shown to substantially reduce accuracy of partial report. These findings suggest that in addition to facilitating character scanning, familiarity may operate in automatically directing attentional resources to a particular spatial region of a display. Such attentional capture may be disruptive if the material to be reported is presented at another location.     

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.