Working memory binding of visual object features in older adults

Accurate mental representation of visual stimuli requires retaining not only the individual features but also the correct relationship between them. This associative process of binding is mediated by working memory (WM) mechanisms. The present study re-examined reports of WM-related binding deficits with aging. In Experiment 1, 31 older and 31 younger adults completed a visual change detection task with feature–location relations presented either simultaneously or sequentially; the paradigm was also designed specifically to minimize the impact of lengthy retention intervals, elaborative rehearsal, and processing demands of multi-stimulus probes. In Experiment 2, 38 older and 42 younger adults completed a modified task containing both feature–location relations and feature–feature conjunctions. In Experiment 1 although feature–location binding was more difficult with sequential compared with simultaneous presentation, the effect was independent of age. In Experiment 2 while older adults were overall slower and less accurate than young adults, there were no age-specific deficits in WM binding. Overall, after controlling for methodological factors, there was no evidence of an age-related visual WM binding deficit for surface or location features. However, unlike younger adults, older adults appeared less able to restrict processing of irrelevant features, consistent with reported declines with age in strategic capacities of WM.     

注意在视觉特征捆绑中的作用

通过两项视觉特征捆绑实验,探讨注意的作用及机制。实验1采用双任务范式,考察不同注意分散水平下的错觉性结合(IC)差异。实验2采用空间提示范式,考察集中注意和分散注意条件下的IC差异。两个实验结果都表明,注意在视觉特征捆绑中起重要作用,集中注意能有效地减少IC的出现。同时,注意对特征捆绑的调节作用表现出距离效应,即近距离比远距离的IC错误多,提示注意的作用机制可能与空间距离信息有关。     

视觉特征捆绑的认知机制研究

以大学生为被试,探讨视觉特征捆绑的认知机制。实验采用空间提示范式,要求被试完成字母形状和颜色的辨别任务,考察集中注意和分散注意条件下的IC差异。结果表明,注意在视觉特征捆绑中起重要作用,集中注意能有效地减少IC的出现。同时注意对特征捆绑的调节作用表现出距离效应,即近距离比远距离的IC错误多,提示了注意的作用机制有可能与空间距离信息有关。     

Visual memory for feature bindings: The disruptive effect of responding to new perceptual input

In the current study, we examined how short-term memory for location–identity feature bindings is influenced by subsequent cognitive and perceptual processing demands. Previous work has shown that memory performance for feature bindings can be disrupted by the presentation of subsequent visual information, particularly when this information is similar to that held in memory. The present study demonstrates that memory performance for feature bindings can be profoundly disrupted by also requiring a response to visual information presented subsequent to the visual memory array. Across five experiments, memory for a location–identity binding was substantially impaired following a localization response to a following item that matched the location but mismatched the identity of the memory target. The results point to an important role for action in the episodic integration processes that control short-term visual memory performance.     

Selective working memory disables inhibition of visual features

Recent research suggests that information held in working memory can facilitate subsequent attentional processing. Here, we explore the negative corollary of this conception: Under which circumstances does information in working memory disrupt subsequent processing? Seventy participants performed visual discriminations in a dual-task paradigm. They were asked to judge colors or shapes in an online attention task under three different working-memory conditions: Same, Switch, or Unknown. In the Same condition, participants selectively maintained one visual feature in working memory, from the same dimension as in the online attention task. In the Switch condition, participants selectively maintained one visual feature in working memory, but had to focus on another visual dimension in the online attention task. In the Unknown condition, participants could not predict which visual feature would be relevant for the working-memory task. We found that irrelevant features in the online attention task were particularly difficult to ignore in the Switch condition, that is, when the irrelevant features belong to a visual dimension that is simultaneously prioritized in selective working memory. The findings are consistent with accounts in terms of neural overlap between working-memory and attention circuits, and suggest that mechanisms of selection, rather than resource limitations, critically determine the extent of visual interference.     

顶叶在特征捆绑中的作用--对一例典型双侧顶叶损伤病人的研究

本实验以一例典型双侧顶叶损伤患者为研究对象,以数字和几何形状为材料,采用形状和颜色特征识别任务,主要考察了顶叶及空间信息是否影响视觉特征捆绑。结果显示,患者在特征捆绑任务上操作成绩较差,错觉性结合错误远远多于特征错误,且正确反应及错觉性结合受刺激间的距离及呈现方式的影响,表现出距离和位置效应。这些结果表明,顶叶在视觉特征捆绑中起重要作用,这种影响作用很可能与空间注意有关。本研究进一步为特征整合理论提供了神经心理学的证据。     

Evidence for auditory feature integration with spatially distributed items

Recent auditory research using sequentially presented, spatially fixed tones has found evidence that, as in vision for simultaneous, spatially distributed objects, attention appears to be important for the integration of perceptual features that enable the identification of auditory events. The present investigation extended these findings to arrays of simultaneously presented, spatially distributed musical tones. In the primary tasks, listeners were required to search for specific cued conjunctions of values for the features of pitch and instrument timbre. In secondary tasks, listeners were required to search for a single cued value of either the pitch or the timbre feature. In the primary tasks, listeners made frequent errors in reporting the presence or absence of target conjunctions. Probability modeling, derived from the visual search literature, revealed that the error rates in the primary tasks reflected the relatively infrequent failure to correctly identify pitch or timbre features, plus the far more frequent illusory conjunction of separately presented pitch and timbre features. Estimates of illusory conjunction rate ranged from 23% to 40%. Thus, a process must exist in audition that integrates separately registered features. The implications of the results for the processing of isolated auditory features, as well as auditory events defined by conjunctions of features, are discussed.     

Feature similarity and feature bias in identification of visually presented letters

Reaction time IRT) to correct identification (ID) was measured for pairs of different letters presented on a memory drum. There were two types of lists. In Type I, visual and name similarity varied orthogonally at two levels. In Type II, one feature was constant at one level, while the other varied at two levels of similarity. For both types of lists, RT is a function of the feature that is more easily extracted from the stimulus. Relative vivaal and name modality biases were estimated, and name bias is relatively more salient than visual bias under these experimental conditions. Specific letters differ in the amount of feature processing required for correct ID and in the relative contribution of visual and name feature effects on this processing.     

两种视觉特征提示对儿童错误记忆发展的影响

采用DRM研究范式,实验一使用示意图提示,探讨特异性视觉特征对于8岁、10岁和12岁儿童错误记忆的影响及其随年龄而产生的变化;实验二使用位置提示,探讨非特异性视觉特征对8岁、10岁和12岁儿童错误记忆的影响及其随年龄增长而产生的变化。实验结果说明:(1)特异性视觉特征提示会显著减少错误记忆,而非特异性视觉提示则会显著增加错误记忆。(2)8～12岁儿童错误记忆随着年龄的增长而增长,这可能是由于儿童随年龄增长不断地发展其形成要义痕迹表征和要义连接的能力所致。(3)特异性视觉特征提示对8岁儿童错误记忆的影响不显著,对10岁和12岁儿童有显著削弱作用,但这种影响在10岁和12岁儿童间没有显著性地增长。(4)非特异性视觉特征提示对8岁儿童错误记忆不产生显著影响,对10岁和12岁儿童有显著的增强作用,且这种影响从8岁至12岁呈显著性增长。     

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。     

Is Posner's "beam" the same as Treisman's "glue"?: On the relation between visual orienting and feature integration theory

In the present study we investigated whether the visually allocated "beam" studied by Posner and others is the same visual attentional resource that performs the role of feature integration in Treisman's model. Subjects were cued to attend to a certain spatial location by a visual cue, and performance at expected and unexpected stimulus locations was compared. Subjects searched for a target letter (R) with distractor letters that either could give rise to illusory conjunctions (PQ) or could not (PB). Results from three separate experiments showed that orienting attention in response to central cues (endogenous orienting) showed similar effects for both conjunction and feature search. However, when attention was oriented with peripheral visual cues (exogenous orienting), conjunction search showed larger effects of attention than did feature search. It is suggested that the attentional systems that are oriented in response to central and peripheral cues may not be the same and that only the latter performs a role in feature integration. Possibilities for future research are discussed.     

Feature binding across different visual dimensions

The human brain represents different kinds of visual feature dimensions in different ways. For example, surface features exhibit some properties that are very different from contour features, and some feature dimensions may be represented more extensively in either the dorsal or the ventral visual stream. Given such differences, we investigated feature binding across different feature dimensions and whether some feature dimensions might be more easily bound together than others. In Experiment 1, we looked at cross-dimension bindings for all combinations of color, orientation, and shape dimensions, while at the same time controlling for feature discriminability. Rates of correct binding, illusory conjunctions, and feature errors were equivalent in all cases. There was no bias so that some feature dimensions were easier to combine than others. In Experiment 2, we manipulated the difficulty of feature discrimination for the key, target-defining feature and the report feature. Rates of binding errors increased with difficulty of the key feature, but not with that of the report feature. The accuracy of feature discrimination could be dissociated from the accuracy of binding the feature to an object. Across both experiments, the accuracy of feature binding was independent of specific feature dimensions or perceptibility. These findings are discussed in relation to both feature integration and multiple-stage accounts of visual feature integration.     

Feature mislocalizations and misjudgments of intercharacter distance

Summary Three experiments were conducted to gather evidence for Wolford's (1975) feature perturbation model and claims derived from it. The first experiment found that perturbation or mislocalization of features toward the foveal center predominated when a distinctive standard for localization was presented and short-term memory factors were minimized. The second experiment found that foveal mislocalizations do seem to cause two figures in the visual field to be reported as closer to one another than they actually are presented. The final experiment provided no support for the notion that interference between figures in the visual field is caused by foveal mislocalizations making features from the figures appear to be at the same location. A distinction between mislocalizations of figures due to feature perturbations and errors due to figures which were correctly localized but not reported in the instructed order was possible in the last two experiments.     

A Place for Every Event and Every Event in Its Place: Memory for Locations and Activities by 4-Year-Old Children

Episodic memories are of specific events and experiences associated with particular times and places. Whereas memory for the temporal aspects of past events has been a focus of research attention, memory for the location in which events were experienced has been less fully investigated. The limited developmental research suggests that preschool-age children, in particular, may have difficulty remembering the location in which they experienced specific events. In 2 experiments, 4-year-old children engaged in 4 unique activities in 4 unique locations in and around a laboratory suite. In Experiment 1, the children had high levels of recall of the activities, the locations, and the conjunctions of activities and locations, implying that they had formed memory representations that featured activities bound in locations. In Experiment 2, we tested whether 1 element of the bound representation—the location of an activity—served as a reliable cue to recall of the other element—the activity itself. The test was positive, providing further evidence that 4-year-old children form mnemonic conjunctions of activities and locations. The results imply that important elements of episodic memory are available to young children.     

Dissociations between featural versus conjunction-based texture processing in infancy: analyses of three potential contributing factors

Many models of object perception posit that adults encode individual features in visual scenes before processing the conjunction relations among these features to generate holistic representations. Prior research suggests that infants detect textural discrepancies based on individual features more readily than those based on feature conjunctions. While these results suggest adult-like qualitative differences in infants' processing of features versus conjunctions, there are potential alternative explanations. We examined three such explanations: (1) failure to process one of the features that constitute the conjunction, (2) failure to encode and remember conjunction information that is necessary to detect conjunction-based textural discrepancies, and (3) the fact that conjunction-based discrepancies involve stimuli that are more similar to original stimuli than those involving feature-based discrepancies. None of these factors could explain 5.5-month-olds' superior processing of featural than conjunction-based textural discrepancies. Thus, in infancy, as in adulthood, features and conjunction relations appear to be processed by qualitatively different mechanisms.     

客体和空间工作记忆中三维图形的特征加工时程

采用单探测变化觉察范式，对三维图形的特征在客体和空间工作记忆中的加工时程进行了探讨。实验一的材料是由不同颜色和形状组成的规则立体图形。实验二的材料是由不同颜色和图案组成的六棱柱。实验结果显示：（1）客体和空间工作记忆绩效均随识记项目数的增加而显著下降；（2）随着刺激呈现时间的延长，客体工作记忆绩效显著提高，空间工作记忆绩效无明显增加；且在三种呈现时间条件下，空间工作记忆绩效均高于客体工作记忆；（3）三维图形中颜色特征的检测绩效优于形状、图案和特征捆绑。这些结果表明，视觉工作记忆中三维图形的特征加工存在显著的时程效应，空间位置加工最早完成，其次是颜色加工，然后是形状与颜色-形状的捆绑，最后是图案与颜色-图案的捆绑。     

The temporal dynamics of visual search: evidence for parallel processing in feature and conjunction searches

Feature and conjunction searches have been argued to delineate parallel and serial operations in visual processing. The authors evaluated this claim by examining the temporal dynamics of the detection of features and conjunctions. The 1st experiment used a reaction time (RT) task to replicate standard mean RT patterns and to examine the shapes of the RT distributions. The 2nd experiment used the response-signal speed-accuracy trade-off (SAT) procedure to measure discrimination (asymptotic detection accuracy) and detection speed (processing dynamics). Set size affected discrimination in both feature and conjunction searches but affected detection speed only in the latter. Fits of models to the SAT data that included a serial component overpredicted the magnitude of the observed dynamics differences. The authors concluded that both features and conjunctions are detected in parallel. Implications for the role of attention in visual processing are discussed.     

Understanding the object benefit in visual short-term memory: the roles of feature proximity and connectedness

Past research has identified visual objects as the units of information processing in visual short-term memory (VSTM) and has shown that two features from the same object can be remembered in VSTM as well (or almost as well) as one feature of that object and are much better remembered than the same two features from two spatially separated objects. It is not clear, however, what drives this object benefit in VSTM. Is it the shared spatial location (proximity), the connectedness among features of an object, or both? In six change detection experiments, both location/proximity and connectedness were found to be crucial in determining the magnitude of the object benefit in VSTM. Together, these results indicate that location/proximity and connectedness are essential elements in defining a coherent visual object representation in VSTM.     

When do letter features migrate? A boundary condition for feature-integration theory

Feature-integration theory postulates that a lapse of attention will allow letter features to change position and to recombine as illusory conjunctions (Treisman & Paterson, 1984). To study such errors, we used a set of uppercase letters known to yield illusory conjunctions in each of three tasks. The first, a bar-probe task, showed whole-character mislocations but not errors based on feature migration and recombination. The second, a two-alternative forced-choice detection task, allowed subjects to focus on the presence or absence of subletter features and showed illusory conjunctions based on feature migration and recombination. The third was also a two-alternative forced-choice detection task, but we manipulated the subjects' knowledge of the shape of the stimuli: In the case-certain condition, the stimuli were always in uppercase, but in the case-uncertain condition, the stimuli could appear in either upper- or lowercase. Subjects in the case-certain condition produced illusory conjunctions based on feature recombination, whereas subjects in the case-uncertain condition did not. The results suggest that when subjects can view the stimuli as feature groups, letter features regroup as illusory conjunctions; when subjects encode the stimuli as letters, whole items may be mislocated, but subletter features are not. Thus, illusory conjunctions reflect the subject's processing strategy, rather than the architecture of the visual system.     

Feature binding in visual short-term memory is unaffected by task-irrelevant changes of location,shape, and color

Three experiments used a change detection paradigm across a range of study–test intervals to address the respective contributions of location, shape, and color to the formation of bindings of features in sensory memory and visual short-term memory (VSTM). In Experiment 1, location was designated task irrelevant and was randomized between study and test displays. The task was to detect changes in the bindings between shape and color. In Experiments 2 and 3, shape and color, respectively, were task irrelevant and randomized, with bindings tested between location and color (Experiment 2) and location and shape (Experiment 3). At shorter study–test intervals, randomizing location was most disruptive, followed by shape and then color. At longer intervals, randomizing any task-irrelevant feature had no impact on change detection for bindings between features, and location had no special role. Results suggest that location is crucial for initial perceptual binding but loses that special status once representations are formed in VSTM, which operates according to different principles, than do visual attention and perception.