记忆系统中图形不同特征的提取

在长时记忆中,图形的颜色、形状和质地等三个特征可以分开表征。那么,图形的不同特征以何种方式提取?在提取过程中,图形的这些特征被激活的程度是否存在着差异?本研究通过对不同提取线索再认成绩的比较,试图对上述问题进行了探讨。结果表明,长时记忆中,图形的形状、颜色和质地的相对痕迹问无差异,而绝对痕迹不同,形状最强,颜色最弱,质地居中。当然,当图形特征数量增加时,它们之问的相互作用是不可避免的,所以,进一步的研究还应考虑到不同特征组合的提取特点,图形的其他特征(如大小、位置等)的提取特点。     

三维图形的客体和空间工作记忆存储机制

采用单探测变化检测范式,通过两个实验探讨了三维双特征图形在视空间工作记忆中的存储方式。实验一的记忆材料为由颜色和形状两种基本特征组成的三维图形,实验二的材料为由基本特征和细节特征组成的三维图形。被试为60名大学本科生（实验1、2各30名,年龄在19~24岁之间,平均21.25岁和21.71岁）。两个实验的结果均显示：特征交换变化条件下的记忆成绩与单一特征变化条件下最小的平均检测正确率无显著差异。这表明,由两种异质特征组成的三维图形在视觉客体和视觉空间工作记忆中均能以整合的单元进行存储。     

两维特征图形的客体和空间工作记忆存储研究

研究采用单探测变化检测范式,考察了两维特征图形在视觉客体和视觉空间工作记忆中的存储机制,并对其容量进行测定。40名被试(平均年龄20.56±1.73岁)随机分为两个等组,分别完成实验一和实验二。实验一的刺激图形由颜色和形状两基本特征组成,实验二的刺激为由不同颜色和开口朝向组成的兰道环。两个实验结果均显示:(1)特征交换变化条件下的记忆成绩与单特征变化条件下最差的记忆成绩差异不显著;(2)空间工作记忆任务的成绩显著优于客体工作记忆任务;(3)被试在视觉工作记忆中能存储2~3个客体和3~4个空间位置。这表明,由两种不同维度特征组成的图形在视觉客体和视觉空间工作记忆中均以整合方式进行存储,空间工作记忆的容量大于客体工作记忆。     

图形的信息编码与表征

图形的信息加工有别于其他视觉信息,主要体现在编码与表征两个方面。图形信息的编码方式和编码时间取决于图形的特征及其复杂性,在此基础上,研究者们分别提出了细节编码模型和范畴编码模型。图形信息表征的几种水平反映了图形信息的编码特性。图形的颜色和形状既可以联合表征,也可以分开表征,这取决于任务的要求。图形其他特征的表征形式还有待于进一步研究。     

客体在视觉工作记忆中的存储机制

采用变化觉察范式,通过两个实验对不同类型视觉信息在工作记忆中的存储机制进行了探讨。实验一中要求记忆的客体由颜色和形状两基本特征构成;实验二中的客体为具有不同颜色及开口朝向的兰道环。通过观察检测项变化方式对记忆绩效的影响,获得以下结论:（1）对颜色和形状两基本特征的存储以整合客体为单位;（2）兰道环的颜色与开口朝向信息难以以整合客体方式存储。笔者推测,视觉工作记忆中存储的整合客体并非如现有理论假设的,是在集中注意参与下创建的,而是由并行加工阶段所获信息构成;客体中所含需集中注意提取的细节特征信息难以与其基本特征信息整合于该客体表征     

视觉客体工作记忆中图形特征存储与捆绑时程

采用单探测变化检测范式,考察了形状和颜色客体在工作记忆中的表征方式、特征检测类型及初始刺激呈现时间对工作记忆表征的影响。结果表明:(1)视觉客体工作记忆的表征包括两个水平,首先是对客体的特征进行加工存储,其次才是对特征的捆绑;(2)不同特征的加工时间不同,颜色的加工完成的较早,记忆效果好,而形状的加工完成的较晚,记忆效果也差,表现出颜色的子系统优势;(3)特征的捆绑不是必需的,只有在任务需要时才进行,并且捆绑的过程符合特征捆绑的双阶段理论。     

颜色、形状和大小相似性与变化性对儿童归纳推理的影响

设计了两个实验任务,探讨了颜色、大小和形状对68名8～10岁儿童归纳推理的影响。结果发现,在相似性任务中,当测试图片分别与两组前提图片在大小和形状(颜色)上一致时,儿童认为测试图形与大小一致图形具有相同属性;当测试图片分别与前提图片在形状和颜色上一致时,儿童倾向于选择形状一致图形具有的属性。在变化性任务中,当两组前提图片分别在大小和形状上变化,而测试图形与前提组图形不同时,儿童认为测试图形与大小变化图形具有相同属性;当两组前提图片分别在颜色和大小(形状)上变化时,儿童的选择没有显著差异;这一结果与同时变化每组前提图片的两个特征差异不显著,表明单独变化颜色、大小和形状来构成推理任务是比较合理的。     

视觉工作记忆中特征绑定关系的记忆机制

弱客体理论认为, 视觉工作记忆系统是由众多特征存储的子系统组成, 不同纬度的特征独立存储在相应的有限容量的子系统中, 相互之间不会竞争记忆资源。而对于特征之间绑定关系的记忆存在不同的观点。一种观点认为绑定关系的记忆需要注意维持, 因此绑定关系的记忆会占用到特征记忆的资源; 另一种观点认为绑定关系的记忆是自动发生的, 不需要注意的维持。本实验的目的是探究特征绑定关系的记忆是否是自动发生的。在实验中, 我们设计了两种任务, 一种任务是只记忆颜色, 另一种任务是记忆颜色跟位置及其之间的绑定关系, 并测试分析视觉工作记忆相关的ERP成分CDA。结果发现两种任务条件下的CDA波幅之间没有显著差异, 说明视觉工作记忆中的特征绑定是自动发生的。     

视觉工作记忆离线态表征的生成机制

视觉工作记忆在人类理解动态变化的视界过程中发挥着重要作用。根据工作记忆状态模型,视觉工作记忆表征可以被存储在在线态或离线态,并可依据任务需求在这两种存储态之间灵活切换。然而,目前还不清楚离线态记忆表征如何由在线态表征转换生成。本研究将通过实验检验两种可能的转换加工假设:巩固假设和衰减假设。研究通过采用序列呈现提取范式来有效引导记忆表征分别被存储在两个不同的表征状态中,并在此基础上对状态转换过程相关的刺激间隔时间和呈现时间进行调控。结果显示,当与状态转换过程相关的时间不足时,会导致记忆表征状态的转换过程与新刺激的在线加工过程叠加,从而发生资源竞争。这一结果符合记忆表征状态转换的巩固假设,即工作记忆的离线态表征通过记忆项目的在线态表征巩固进入离线态而形成。     

表征在视觉工作记忆中的存储单位:特征、客体或二者并存?（英文）

传统视觉工作记忆(VWM)的研究认为视觉客体以特征或客体方式存储。最近研究者提出特征和客体可能在VWM中并存,但尚未有研究直接对其检验。本研究采用变化觉察范式,以三个实验对该问题进行了探讨。实验中要求被试记忆有颜色的线条的朝向而忽略颜色。结果发现,无关维度颜色得到加工,但并不影响朝向特征的高相似效应(特征间相似性越高,记忆绩效越高);同时颜色与朝向的绑定关系存在。该结果支持特征与客体同时在VWM存储的假设。     

Binding in short-term visual memory

The integration of complex information in working memory, and its effect on capacity, shape the limits of conscious cognition. The literature conflicts on whether short-term visual memory represents information as integrated objects. A change-detection paradigm using objects defined by color with location or shape was used to investigate binding in short-term visual memory. Results showed that features from the same dimension compete for capacity, whereas features from different dimensions can be stored in parallel. Binding between these features can occur, but focused attention is required to create and maintain the binding over time, and this integrated format is vulnerable to interference. In the proposed model, working memory capacity is limited both by the independent capacity of simple feature stores and by demands on attention networks that integrate this distributed information into complex but unified thought objects.     

The representation of color and form in long-term memory

Color and form are elementary stimulus encoding dimensions that have effects on the representation of visual stimuli at early processing stages. Little is known, however, about their effects on visual long-term memory. In three experiments we investigated whether color is part of the memory representation, whether color and form are bound in the memory representation, and the effect of color context on memory performance. Experimental results suggest that color is part of the memory representation and that color and form can be represented separately in memory and accessed independently. We suggest that the binding of color and form is a deliberate strategic act that requires focal attention, not a natural consequence of processing visual stimuli. We compare our results with the predictions of two computational memory models regarding feature binding. The effect of color context was not straightforward; however, results are consistent with the encoding specificity principle.     

Retrospective cues based on object features improve visual working memory performance in older adults

Research with younger adults has shown that retrospective cues can be used to orient top-down attention toward relevant items in working memory. We examined whether older adults could take advantage of these cues to improve memory performance. Younger and older adults were presented with visual arrays of five colored shapes; during maintenance, participants were presented either with an informative cue based on an object feature (here, object shape or color) that would be probed, or with an uninformative, neutral cue. Although older adults were less accurate overall, both age groups benefited from the presentation of an informative, feature-based cue relative to a neutral cue. Surprisingly, we also observed differences in the effectiveness of shape versus color cues and their effects upon post-cue memory load. These results suggest that older adults can use top-down attention to remove irrelevant items from visual working memory, provided that task-relevant features function as cues.     

Multidimensional visual statistical learning

Recent studies of visual statistical learning (VSL) have demonstrated that statistical regularities in sequences of visual stimuli can be automatically extracted, even without intent or awareness. Despite much work on this topic, however, several fundamental questions remain about the nature of VSL. In particular, previous experiments have not explored the underlying units over which VSL operates. In a sequence of colored shapes, for example, does VSL operate over each feature dimension independently, or over multidimensional objects in which color and shape are bound together? The studies reported here demonstrate that VSL can be both object-based and feature-based, in systematic ways based on how different feature dimensions covary. For example, when each shape covaried perfectly with a particular color, VSL was object-based: Observers expressed robust VSL for colored-shape sub-sequences at test but failed when the test items consisted of monochromatic shapes or color patches. When shape and color pairs were partially decoupled during learning, however, VSL operated over features: Observers expressed robust VSL when the feature dimensions were tested separately. These results suggest that VSL is object-based, but that sensitivity to feature correlations in multidimensional sequences (possibly another form of VSL) may in turn help define what counts as an object.     

视觉工作记忆中基于客体的存储机制：来自ERPs的证据

该研究以简单形状和颜色构成的客体为材料,采用延迟匹配范式,通过记录事件相关电位,以反映工作记忆表征与知觉输入间冲突的N270为指标,就视觉工作记忆中的客体存储机制进行了探讨。结果发现,无关维度特征变化与目标维度特征变化均可诱发N270。该结果表明,视觉工作记忆对客体目标特征进行存储时,无关特征亦自动得到选择加工,支持基于客体的存储说。     

Object-based representations govern both the storage of information in visual short-term memory and the retrieval of information from it

Interest is growing in how information is retained in visual short-term memory (VSTM). We describe an experiment that assesses VSTM within the context of multidimensional signal detection theory. On every trial, participants were presented with a 250-ms display containing four colored shapes. They were then probed 900 ms later with a colored shape and made separate old/new judgments about the color and the shape. In any particular trial, one, both, or neither of the probed features had been presented. Performance differed according to whether both probed features belonged to a single object or to two different objects. When both probed features belonged to the same object, featural retrieval was better than would be predicted by independent feature storage. When both probed features belonged to two different objects, featural retrieval was worse than would be predicted by independent feature storage. We conclude that storage in and retrieval from VSTM operate on the basis of object-based representations.     

Pitch as a phonemic cue

Three experiments that were designed to determine how pitch information is represented in auditory memory are reported. A same-different reaction time was used in all three experiments. Previous experiments have interpreted the finding of faster “same” responses to acoustically identical pairs than to pairs that are phonemically identical but acoustically distinct as indicating that there is a memory that preserves auditory information. It has been assumed that this can be used to match “same” pairs only if the formant frequencies of the members of the pair are the same. In the first experiment, the size of this matching advantage for pairs with identical formant frequencies was not altered when the members of the pair were on different pitches. This indicates that pitch is represented separately from the formants at the auditory level. The second and third experiments used a bigger pitch difference when the pairs were on a different pitch, which, for one of the stimulus sets, resulted in a change in vowel quality but not in the identity of the consonant. In the other stimulus set, both phonemes of the syllable remained the same when presented on different pitches. The matching advantage was reduced when the stimuli were on different pitches for both stimulus sets. This indicates that a difference in pitch can prevent matching at the auditory level under some circumstances. An additional finding, a reduced residual matching advantage when the syllable changes, indicates that at least a syllable-length representation is held in auditory memory. The results are discussed with respect to how the representation in auditory memory might be used in the perception of speech produced by different speakers.     

How retaining objects containing multiple features in visual working memory regulates the priority for access to visual awareness

The content of visual working memory influences the access to visual awareness. Thus far, research has focused on retention of a single feature, whereas memoranda in real life typically contain multiple features. Here, we intermixed a delayed match-to-sample task to manipulate VWM content, and a breaking Continuous Flash Suppression (b-CFS) task to measure prioritization for visual awareness. Observers memorized either the color (Exp. 1), the shape (Exp. 2) or both the features (Exp. 3) of an item and indicated the location of a suppressed target. We observed that color-matching targets broke suppression faster than color-mismatching targets both when color was memory relevant or irrelevant. Shape only impacted priority for visual awareness through an interaction with color. We conclude that: (1) VWM can regulate the priority of visual information to access visual awareness along a single feature dimension; (2) different features of a memorandum vary in their potency to impact access to visual awareness, and the more dominant feature may even suppress the effect of the less dominant feature; (3) even stimuli that match an irrelevant feature dimension of the memorandum can be prioritized for visual awareness.