三维图形的视空间工作记忆容量研究

采用三维几何图形为材料,通过单探测变化觉察范式来测定视觉工作记忆的存储容量,并比较客体工作记忆和空间工作记忆容量的差异。实验1、2的材料分别为由颜色和形状两个基本特征组成的三维图形和由一个基本特征和一个细节特征组成的三维图形。两个实验结果显示,被试能在视觉工作记忆中存储约2-3个客体和4个空间位置,空间工作记忆容量显著大于客体工作记忆容量。进一步的比较发现,被试对由两个基本特征组成的三维图形的存储容量大于由一个基本特征和一个细节特征组成的三维图形。这表明,组成三维图形的特征类型对视空间工作记忆的存储容量有显著影响。     

体感游戏训练对生物运动工作记忆容量的影响

传递生物体运动信息的生物运动在工作记忆中有着独立于一般视觉客体的存储空间。尽管研究发现电子游戏训练可提高工作记忆(如一般视觉客体)容量,但尚未有研究探讨游戏训练对生物运动工作记忆容量的影响。本研究采用Kinect体感游戏训练,首次对该问题进行探讨。实验中控制组被试与实验组被试均先后做两次生物运动记忆实验,但实验组在第一次实验后进行为期14天的体感游戏训练。结果发现,尽管生物运动工作记忆绩效在后测时较前测有显著上升,但是游戏训练并未显著提高实验组的记忆绩效,说明生物运动工作记忆并不受体感交互游戏训练影响。     

图形规则性对客体和空间工作记忆存储的影响

采用单探测变化检测范式,考察了单维度特征图形在视觉客体和视觉空间工作记忆中的存储机制,并对这两种视觉工作记忆的容量进行测定。结果显示,在客体工作记忆中,规则图形的记忆成绩显著高于不规则图形,但在空间工作记忆中,这两种图形的记忆成绩无显著差异;空间工作记忆的存储容量显著大于客体工作记忆容量,分别为4-5个位置和3-4个客体。这表明,图形规则性影响了客体工作记忆的存储但不影响空间工作记忆的存储,由单维度特征组成的图形在客体工作记忆中是以特征为单元储存,而在空间工作记忆中是以整合方式储存。     

客体复杂度影响工作记忆可存储的客体数目

采用变化觉察范式,以对侧延迟活动（contralateral delay activity,CDA）的幅值为指标,通过操纵记忆刺激的复杂程度,对视觉工作记忆中可存储的客体数目（即工作记忆容量）问题进行了探讨。结果表明,2个复杂客体条件下的CDA幅值与4个复杂客体条件无显著差异,而4个简单客体条件的CDA幅值显著高于2个简单客体条件,即CDA的幅值受客体复杂度的调节。基于该结果推论：并非视觉工作记忆总能存储4个客体,其可存储的客体数目受客体复杂度影响。     

知觉表征精度对工作记忆中抑制干扰能力的影响

工作记忆的容量十分有限,需要选择性地抑制与目标无关信息的干扰,工作记忆容量高的个体,其抑制干扰的能力也更强。本研究采用带有不同形状干扰刺激的色块颜色回忆任务考察干扰对工作记忆容量和表征精度的影响,结果发现,当负荷超出工作记忆容量范围时,干扰减少了记忆所能表征客体的个数;当负荷在工作记忆容量范围内时,干扰降低了记忆中表征客体的精度。更进一步,研究采用独立的知觉任务来测量知觉表征的精度,并探讨作为信息加工的初始阶段的知觉表征如何影响工作记忆加工过程中抑制干扰的能力。将实验中收集的48名有效被试按照知觉表征精度的高低平均分为两组,结果发现上述干扰效应主要表现在知觉表征精度较低的组中,并且该组中知觉表征精度越高的个体,其工作记忆抑制干扰的能力也越强。本研究为实践中通过知觉训练来提升工作记忆的抑制干扰能力提供了理论指导。     

工作记忆广度与汉语句子语境效应的关系

采用计算机快速系列视觉呈现技术,以反应时为指标,利用命名法,从工作记忆容量个体差异的角度,探讨汉语句子阅读中的语境效应。本研究将句子的语境效应分为两个来源：一个是自动激活扩散的词汇之间的语义启动,另一个是相互作用的句子水平的主题启动。结果表明：词汇间的语义启动不受工作记忆容量的影响,并且不易受到无关记忆任务的干扰。句子水平的主题启动会受到工作记忆容量的影响：工作记忆广度较高的读者能出现主题水平的语境效应,但是在无关记忆任务的干扰下,句子主题水平的语境效应消失;低广度的读者在无外部记忆负荷和有外部记忆负荷两种条件下都没有出现主题水平的语境效应。工作记忆容量对那些需要较多认知资源的加工过程产生显著的影响,实验结果符合工作记忆容量限制理论     

基于空间方位信息的构型对视觉工作记忆绩效的影响

通过考察构成视觉客体构型的两种因素在视觉工作记忆任务中的影响, 探讨了构型对视觉工作记忆绩效的作用机制。采用变化觉察实验范式, 在构型朝向不变和旋转两种条件下, 系统地控制构型中的客体相对方位和整体几何形态两种因素的变化, 考察其对视觉工作记忆绩效的影响。实验结果显示, 无论构型朝向不变还是旋转, 只要客体相对方位保持一致, 工作记忆绩效就可以维持较高水平, 而几何形态没有表现出显著作用。上述发现提示构型客体相对方位是构型影响视觉工作记忆绩效的主要因素。     

空间距离对视觉工作记忆巩固的影响

以往研究发现,个体对不同类型的视觉信息进行视觉工作记忆巩固的模式存在差异,如对于方向信息,一次只能有一个项目被巩固进入视觉工作记忆系统,而对于颜色信息,个体则可以一次巩固两个项目进入视觉工作记忆系统。但对于视觉信息的巩固模式是否会受其他因素的影响,目前仍然没有明确的定论。本研究将探讨视觉信息的巩固模式是否可能受到记忆项目空间距离因素的影响。研究采用变化觉察范式、序列-同时呈现操作及控制记忆项目呈现间距的方法,通过3个实验考察记忆项目之间的空间距离是否能够影响个体对颜色信息和方向信息的巩固模式。在三种空间距离水平上序列呈现或同时呈现两个记忆项目,实验结果一致发现记忆项目之间的空间距离会对视觉工作记忆巩固模式产生明显影响,个体在同时呈现条件下的正确率会随着空间距离的增大而降低。这些结果表明对同一类视觉信息进行巩固的过程中所存在的项目数量限制并不是固定的,个体可以采用序列模式或有限容量的并行模式对同一类信息进行巩固,巩固的模式可能与视觉空间注意的分配以及视觉信息所能获得的注意资源有关。     

网格对工作记忆中视觉客体空间位置编码的影响

为探究网格在工作记忆中对视觉客体位置编码的影响,本研究采用n-back范式,通过客体位置的确定性和网格出现的不同认知加工阶段,探索了网格线在空间工作记忆视觉客体位置记忆中的作用机制.实验1的结果表明,被试将依据客体的位置确定性强弱来选择类别编码或坐标编码.实验2的结果显示,网格在识记阶段可能有利于位置记忆,而在提取阶段可能有干扰作用.     

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。     

The effects of categorical similarity and feature-space proximity on visual working memory processing

Two patterns of data predict that similarity has a positive effect and a negative effect on visual working memory (VWM) processing. We assume that these two empirical outcomes do not distinguish categorical similarity from feature-space proximity, resulting in this divergence. To investigate how categorical similarity and feature-space proximity modulate VWM, we tested memory for an array of pictures drawn from either mixed categories or a single category in which feature-space proximity varied along a morph continuum in a change-detection task. We found that memory under the mixed-category condition was better than that under the single-category condition, whereas memory under high feature-space proximity was superior to that under low feature-space proximity. These patterns were unaffected by manipulations of stimulus type (faces or scenes), encoding duration (limited or self-paced), and presentation format (simultaneous or sequential). These results are consistent with our hypotheses that categorical similarity inhibits VWM, whereas feature-space proximity facilitates VWM. We also found that memory for items with low feature-space proximity benefited more from mixed-category encoding than that for items with high feature-space proximity. Memory for faces benefited more from mixed-category encoding than scenes, whereas memory for scenes benefited more from feature-space proximity than faces. These results suggest that centre-surround inhibition organization might underlie similarity effects in VWM. Centre-surround inhibition organization for complex real-world objects could have both categorical level and feature-space level. The feature-space level might differ by category.     

Understanding age-related reductions in visual working memory capacity: Examining the stages of change detection

Visual working memory (VWM) capacity is reduced in older adults. Research has shown age-related impairments to VWM encoding, but aging is likely to affect multiple stages of VWM. In the present study, we recorded the event-related potentials (ERPs) of younger and older adults during VWM maintenance and retrieval. We measured encoding-stage processing with the P1 component, maintenance-stage processing with the contralateral delay activity (CDA), and retrieval-stage processing by comparing the activity for old and new items (old–new effect). Older adults showed lower behavioral capacity estimates (K) than did younger adults, but surprisingly, their P1 components and CDAs were comparable to those of younger adults. This remarkable dissociation between neural activity and behavior in the older adults indicated that the P1 and CDA did not accurately assess their VWM capacity. However, the neural activity evoked during VWM retrieval yielded results that helped clarify the age-related differences. During retrieval, younger adults showed early old–new effects in frontal and occipital areas and a late central–parietal old–new effect, whereas older adults showed a late right-lateralized parietal old–new effect. The younger adults’ early old–new effects strongly resembled an index of perceptual fluency, suggesting that perceptual implicit memory was activated. The activation of implicit memory could have facilitated the younger adults’ behavior, and the lack of these early effects in older adults may suggest that they have much lower-resolution memory than do younger adults. From these data, we speculated that younger and older adults store the same number of items in VWM, but that younger adults store a higher-resolution representation than do older adults.     

Effects of semantic context in the naming of pictures and words

Two experiments investigated whether lexical retrieval for speaking can be characterized as a competitive process by assessing the effects of semantic context on picture and word naming in German. In Experiment 1 we demonstrated that pictures are named slower in the context of same-category items than in the context of items from various semantic categories, replicating findings by Kroll and Stewart (Journal of Memory and Language, 33 (1994) 149). In Experiment 2 we used words instead of pictures. Participants either named the words in the context of same- or different-category items, or produced the words together with their corresponding determiner. While in the former condition words were named faster in the context of same-category items than of different-category items, the opposite pattern was obtained for the latter condition. These findings confirm the claim that the interfering effect of semantic context reflects competition in the retrieval of lexical entries in speaking.     

The effects of direction similarity in visual working memory: Behavioural and event-related potential studies

Object similarity can improve visual working memory (VWM) performance in the change-detection task, but impair the recognition performance when it occurs at retrieval of VWM in the recognition task. The effect of direction similarity is an issue that has not been well resolved. Furthermore, electrophysiological evidence in support of the mechanisms that underlie the effects of similarity is still scarce. In the current study, we conducted three behavioural experiments to examine the effects of direction similarity on memory performance with regard to both the encoding and retrieval phases of VWM and one event-related potential (ERP) experiment to explore the neural signatures of direction similarity in VWM. Our behavioural studies indicated that direction similarity improved performance when it occurred at the encoding phase but impaired performance when it occurred at the retrieval phase. Moreover, the ERP experiment showed that the amplitude of the contralateral delay activity (CDA) increased with the increasing set size for similar but not dissimilar directions. In addition, the CDA amplitude for similar directions was lower than that for dissimilar directions at set size 2. Taken together, these findings suggest that direction similarity at encoding has a positive effect on VWM performance and at retrieval has a negative effect. Given that VWM capacity depends on information load and the number of objects, the positive effect of similarity may be attributed to reduced information load of memory objects.     

多特征刺激在视觉工作记忆中的存储模式

使用事件相关电位技术, 采用变化觉察范式, 以双色块和单色块为刺激材料, 通过两个实验探讨了多特征刺激在视觉工作记忆中的存储模式。实验1通过对双色块和单色块的比较来考察特征数量对视觉工作记忆资源分配的影响, 通过操控双色方块的变化幅度来考察精度需求对资源分配的影响。结果发现, 特征数量的增加诱发了更强的对侧延迟活动(CDA), 而精度需求的提高并没有引起对侧延迟活动上的差异, 却诱发了指示自上而下的控制的晚期正成分(LPC)的增强。实验2通过在测验阶段加入指示可能变化的部分的提示符, 发现提示符并未能促进变化觉察的行为反应。整个研究表明, 特征数量影响视觉工作记忆资源的分配, 而精度需求并不起作用, 同时多特征刺激在视觉工作记忆中的存储单位并不是单个的独立特征, 而是整合的客体。     

Reward-priming impacts visual working memory maintenance: Evidence from human electrophysiology

Reward can benefit visual processing of reward-associated objects in a non-strategic way. Recent studies have suggested that such influence extends also to visual working memory (VWM) representations of reward-associated stimuli. However, it is not clear yet which mechanisms underlie the behavioural effects in VWM tasks: reward could directly impact on our ability to maintain representations in VWM or it could influence memory indirectly via priming of attentional selection. To distinguish between these alternatives we measured event-related potential indices of selective attention – the N2pc – and VWM maintenance – the CDA (contralateral delay activity) – while participants completed a VWM task. Results show that reward outcome in one trial caused similarly coloured targets to be strongly represented in VWM in subsequent trials, as expressed in a larger-amplitude CDA This was not preceded by a corresponding effect on attentional selection, in so far as our key manipulation had no impact on the N2pc. In a second experiment, we found that reward priming produced a behavioural benefit that emerged over time, suggesting that the representations of reward-associated items stored in VWM are more resistant to interference and decay. We conclude that when the task stresses VWM maintenance, it is at this representational level that reward will have impact.     

样例呈现方式对概念训练类别表征的影响

以往研究发现训练形式会影响类别学习的表征方式。实验采用学习-迁移范式,探究概念训练中样例的呈现方式对类别表征的影响。实验中被试通过不同呈现方式来学习类别知识,在学习3个block之后对其进行测验。实验结果表明:(1)学习单样例和同一类别比较学习的被试在测验阶段的成绩与学习阶段之间没有差异;(2)学习不同类别比较学习的被试在测验阶段的成绩大幅度下降。因此得出结论,在概念训练中,不同类别比较学习导致被试形成类别间信息的表征。     

Adapting to test structure: Letting testing teach what to learn

We propose that we encode and store information as a function of the particular ways we have used similar information in the past. More specifically, we contend that the experience of retrieval can serve as a powerful cue to the most effective ways to encode similar information in comparable future learning episodes. To explore these ideas, we did two studies in which all participants went through study–test cycles of single category lists while we manipulated the nature of the recognition tests. The recognition tests either included only same-category lures or only different-category lures. The experience of repeated testing leads participants to avoid conceptual-based strategies but only when conceptual knowledge was poorly diagnostic for recognition (i.e., in the same-category lures condition). In a second study with a similar manipulation, we showed that repeated testing with lures from the same category as study items improved performance in a final recall surprise test compared to conditions in which different-category lures were used. Such a difference is akin to the one obtained when encoding instructions focus on distinctive item features compared to cases in which the focus is on relational processing. We suggest that testing requirements lead to adaptive changes at encoding.     

Beyond slots and resources: Grounding cognitive concepts in neural dynamics

Research over the past decade has suggested that the ability to hold information in visual working memory (VWM) may be limited to as few as three to four items. However, the precise nature and source of these capacity limits remains hotly debated. Most commonly, capacity limits have been inferred from studies of visual change detection, in which performance declines systematically as a function of the number of items that participants must remember. According to one view, such declines indicate that a limited number of fixed-resolution representations are held in independent memory “slots.” Another view suggests that such capacity limits are more apparent than real, but emerge as limited memory resources are distributed across more to-be-remembered items. Here we argue that, although both perspectives have merit and have generated and explained impressive amounts of empirical data, their central focus on the representations—rather than processes—underlying VWM may ultimately limit continuing progress in this area. As an alternative, we describe a neurally grounded, process-based approach to VWM: the dynamic field theory. Simulations demonstrate that this model can account for key aspects of behavioral performance in change detection, in addition to generating novel behavioral predictions that have been confirmed experimentally. Furthermore, we describe extensions of the model to recall tasks, the integration of visual features, cognitive development, individual differences, and functional imaging studies of VWM. We conclude by discussing the importance of grounding psychological concepts in neural dynamics, as a first step toward understanding the link between brain and behavior.