工作记忆中“组块”概念的演化及理论模型

在Miller提出“神奇的数字7±2”之后,“块”被很多理论作为个体工作记忆加工过程中具有稳定结构并可用于衡量记忆容量的单位。但随着研究者对“组块”研究的深入,他们对组块的定义也在发生着改变。与此同时,不少研究发现个体的年龄阶段与其主要采用的组块层级相对应,但尚不清楚组块层级的转换是否存在固定的年龄区间,且对组块机制的解释仍存在分歧。因此本文针对组块定义的发展与演变、年龄阶段特征及其机制三方面展开综合讨论。未来的研究可以更多探讨长时记忆在工作记忆组块运行机制中的作用,完善不同年龄阶段个体的组块特征,以及怎样发挥复述策略和“少即是多”原则在组块过程中的优势等问题。     

Distinct modes of executing movement sequences: reacting, associating, and chunking

Responding to individual key-specific stimuli in entirely unfamiliar keying sequences is said to involve a reaction mode. With practice, short keying sequences can be executed in the chunking mode. This is indicated by the first stimulus sufficing for rapid execution of the entire sequence. The present study explored whether an associative mode develops also in participants who practice short keying sequences. This associative mode would involve priming by earlier events of responses to external stimuli, and is believed to be responsible for skill in the Serial Reaction Time task. In the present study participants practiced two discrete 6-key sequences. In the ensuing test phase, participants were prevented from using the chunking mode by including two deviant stimuli in most sequences. The results from the remaining - unchanged - familiar sequences confirmed that participants no longer used the chunking mode, but as predicted by associative learning these sequences were executed faster than unfamiliar sequences.     

高功能孤独症幼儿空间工作记忆的组块加工缺陷

孤独症谱系障碍者存在空间工作记忆加工缺陷,其具体受损环节尚不明确。组块是一种有效的策略性信息编码方式,是空间工作记忆的关键环节。高度结构化的刺激容易形成高水平组块,因此,刺激结构化程度对记忆效果的影响能够反映个体的组块加工能力。研究采用Sternberg空间工作记忆任务、Corsi空间广度任务,加入刺激结构化因素,考察高功能孤独症幼儿是否存在组块加工缺陷,并探讨组块加工是否直接影响到空间工作记忆容量。实验1采用Sternberg空间工作记忆任务,结果表明,ASD幼儿存在明显的组块加工缺陷。在易于组块的高结构化条件下,健康幼儿的记忆成绩明显较高,而ASD幼儿在高、低结构化条件下的记忆成绩并无显著差异。实验2采用Corsi空间广度任务,结果显示,不论高、低结构化条件,ASD幼儿的空间工作记忆容量均显著低于健康幼儿。但ASD幼儿由于存在组块加工缺陷,在高、低结构化条件下的记忆成绩差异较健康幼儿小。因此,ASD幼儿的组块能力一定程度上影响了空间工作记忆容量。此外,记忆存储器的异常可能也是ASD幼儿空间工作记忆容量不足的重要原因。研究表明,ASD幼儿的空间组块缺陷主要由于弱中央统合的认知风格,他们缺乏自上而下的组块加工动机,难以主动对刺激形成高水平组块编码,从而影响记忆效果。     

Statistically Induced Chunking Recall: A Memory-Based Approach to Statistical Learning

The computations involved in statistical learning have long been debated. Here, we build on work suggesting that a basic memory process, chunking, may account for the processing of statistical regularities into larger units. Drawing on methods from the memory literature, we developed a novel paradigm to test statistical learning by leveraging a robust phenomenon observed in serial recall tasks: that short-term memory is fundamentally shaped by long-term distributional learning. In the statistically induced chunking recall (SICR) task, participants are exposed to an artificial language, using a standard statistical learning exposure phase. Afterward, they recall strings of syllables that either follow the statistics of the artificial language or comprise the same syllables presented in a random order. We hypothesized that if individuals had chunked the artificial language into word-like units, then the statistically structured items would be more accurately recalled relative to the random controls. Our results demonstrate that SICR effectively captures learning in both the auditory and visual modalities, with participants displaying significantly improved recall of the statistically structured items, and even recall specific trigram chunks from the input. SICR also exhibits greater test–retest reliability in the auditory modality and sensitivity to individual differences in both modalities than the standard two-alternative forced-choice task. These results thereby provide key empirical support to the chunking account of statistical learning and contribute a valuable new tool to the literature.     

Coherence and recurrency: maintenance,control and integration in working memory

Working memory (WM), including a ‘central executive’, is used to guide behavior by internal goals or intentions. We suggest that WM is best described as a set of three interdependent functions which are implemented in the prefrontal cortex (PFC). These functions are maintenance, control of attention and integration. A model for the maintenance function is presented, and we will argue that this model can be extended to incorporate the other functions as well. Maintenance is the capacity to briefly maintain information in the absence of corresponding input, and even in the face of distracting information. We will argue that maintenance is based on recurrent loops between PFC and posterior parts of the brain, and probably within PFC as well. In these loops information can be held temporarily in an active form. We show that a model based on these structural ideas is capable of maintaining a limited number of neural patterns. Not the size, but the coherence of patterns (i.e., a chunking principle based on synchronous firing of interconnected cell assemblies) determines the maintenance capacity. A mechanism that optimizes coherent pattern segregation, also poses a limit to the number of assemblies (about four) that can concurrently reverberate. Top-down attentional control (in perception, action and memory retrieval) can be modelled by the modulation and re-entry of top-down information to posterior parts of the brain. Hierarchically organized modules in PFC create the possibility for information integration. We argue that large-scale multimodal integration of information creates an ‘episodic buffer’, and may even suffice for implementing a central executive.     

基于概念复杂度的加工容量观

探讨了一个认知科学的概念——容量,主要是介绍一种基于概念维度的加工容量观.这种观点认为加工容量最好以进入某一特定运算过程的独立维度来定义,容量的增长意味着可以表征更多的维度,而概念的组块与分割是常用的表征策略.个体差异通过表征的清晰度和有效性的差异来表现,而认知的发展则是成熟与经验相互作用的结果.     

Interleaving reading and acting while following procedural instructions

Memory for an interactive procedure acquired from written instructions is improved if the procedure can be carried out while the instructions are being read. The size of the read-act cycle was manipulated in Experiments 1 and 2 by comparing chunked instruction-following, in which 3 or 4 steps are read then performed with single-step conditions. In both experiments, enforced chunking improved subsequent unaided performance of the procedure. In Experiment 3, participants were allowed to manage the interleaving of reading and acting. The imposition of a small behavioral cost (a single mouse point-and-click operation) on the switch between instructions and device encouraged more chunking and better subsequent test performance. The authors concluded that the interleaving of reading and acting is an important practical concern in the design of interactive procedures and that more effective chunk-based strategies can quite readily be encouraged.     

洗掉不愉快的经历，留住幸福的时刻——回忆情绪事件对人们清洗/保留倾向的影响

基于道德与清洗的联系,我们假设,人们可能在经历非道德范畴的负效价事件后也会引发出“清洗”的倾向,而在经历正效价事件后则会引发“保留”的倾向。三个实验来验证这个假设,结果表明,被试在回忆道德或非道德范畴的负效价事件时,都会更多地选择具有清洗功能的物品,表现出“清除”负效价事件的倾向;相反,被试回忆正效价事件时,则会倾向选择具有保留功能的物品,表现出将正效价事件“保留”的倾向。     

The best of all possibleworlds

The Argument from Inferiority holds that our world cannot be the creation of an omnipotent and omnibenevolent being; for if it were, it would be the best of all possible worlds, which evidently it is not. We argue that this argument rests on an implausible principle concerning which worlds it is permissible for an omnipotent being to create: roughly, the principle that such a being ought not to create a non-best world. More specifically, we argue that this principle is plausible only if we assume that there is a best element in the set of all possible worlds. However, as we show, there are conceivable scenarios in which that assumption does not hold.     

学习材料组块方式对相似词长时记忆的影响

已有关于材料相似性影响短时记忆的研究提示, 不相似材料组块相比于相似材料组块可能促进记忆。为验证该假设, 该研究采用学习-测查范式, 通过4个实验考察了学习材料组块方式对相似词长时记忆的影响及机制。结果发现：1)与相似词组块相比, 不相似词组块促进了相似词记忆; 2)不相似词组块的促进效应是通过增强相似词表共同词根的记忆而实现的; 3)不相似词组块的促进效应可能依赖于语音相似性。该结果说明不相似词组块可能是促进相似词汇记忆的有效途径之一。     

对变化/分割模型的检验(I)

用两个实验对变化／分割模型进行了检验。实验１控制目标时距和该时距内的填充数字系列,操纵数字系列的分割段数;实验２控制目标时距内的填充数字系列的间距,操纵目标时距及其中填充数字系列的分割段数,要求被试用再现法和多数估计法分别复制目标时距,并进行立即估计和延迟估计。结果显示：与存储容量模型和加工时间模型相比较,变化／分割模型对时间估计的解释具有更高的预测效度     

Processing capacity defined by relational complexity: implications for comparative, developmental, and cognitive psychology

Working memory limits are best defined in terms of the complexity of the relations that can be processed in parallel. Complexity is defined as the number of related dimensions or sources of variation. A binary relation has one argument and one source of variation; its argument can be instantiated in only one way at a time. A binary relation has two arguments, two sources of variation, and two instantiations, and so on. Dimensionality is related to the number of chunks, because both attributes on dimensions and chunks are independent units of information of arbitrary size. Studies of working memory limits suggest that there is a soft limit corresponding to the parallel processing of one quaternary relation. More complex concepts are processed by "segmentation" or "conceptual chunking." In segmentation, tasks are broken into components that do not exceed processing capacity and can be processed serially. In conceptual chunking, representations are "collapsed" to reduce their dimensionality and hence their processing load, but at the cost of making some relational information inaccessible. Neural net models of relational representations show that relations with more arguments have a higher computational cost that coincides with experimental findings on higher processing loads in humans. Relational complexity is related to processing load in reasoning and sentence comprehension and can distinguish between the capacities of higher species. The complexity of relations processed by children increases with age. Implications for neural net models and theories of cognition and cognitive development are discussed.     

Shedding light on insight: Priming bright ideas

Previous research has characterized insight as the product of internal processes, and has thus investigated the cognitive and motivational processes that immediately precede it. In this research, however, we investigate whether insight can be catalyzed by a cultural artifact, an external object imbued with learned meaning. Specifically, we exposed participants to an illuminating lightbulb - an iconic image of insight - prior to or during insight problem-solving. Across four studies, exposing participants to an illuminating lightbulb primed concepts associated with achieving an insight, and enhanced insight problem-solving in three different domains (spatial, verbal, and mathematical), but did not enhance general (non-insight) problem-solving.     

Chunking mechanisms in human learning

Pioneering work in the 1940s and 1950s suggested that the concept of 'chunking' might be important in many processes of perception, learning and cognition in humans and animals. We summarize here the major sources of evidence for chunking mechanisms, and consider how such mechanisms have been implemented in computational models of the learning process. We distinguish two forms of chunking: the first deliberate, under strategic control, and goal-oriented; the second automatic, continuous, and linked to perceptual processes. Recent work with discrimination-network computational models of long- and short-term memory (EPAM/CHREST) has produced a diverse range of applications of perceptual chunking. We focus on recent successes in verbal learning, expert memory, language acquisition and learning multiple representations, to illustrate the implementation and use of chunking mechanisms within contemporary models of human learning.     

In defense of abstract conceptual representations

An extensive program of research in the past 2 decades has focused on the role of modal sensory, motor, and affective brain systems in storing and retrieving concept knowledge. This focus has led in some circles to an underestimation of the need for more abstract, supramodal conceptual representations in semantic cognition. Evidence for supramodal processing comes from neuroimaging work documenting a large, well-defined cortical network that responds to meaningful stimuli regardless of modal content. The nodes in this network correspond to high-level “convergence zones” that receive broadly crossmodal input and presumably process crossmodal conjunctions. It is proposed that highly conjunctive representations are needed for several critical functions, including capturing conceptual similarity structure, enabling thematic associative relationships independent of conceptual similarity, and providing efficient “chunking” of concept representations for a range of higher order tasks that require concepts to be configured as situations. These hypothesized functions account for a wide range of neuroimaging results showing modulation of the supramodal convergence zone network by associative strength, lexicality, familiarity, imageability, frequency, and semantic compositionality. The evidence supports a hierarchical model of knowledge representation in which modal systems provide a mechanism for concept acquisition and serve to ground individual concepts in external reality, whereas broadly conjunctive, supramodal representations play an equally important role in concept association and situation knowledge.     

Stimulus and response chunking in the Hebb Digits task

Using the Hebb Digits task, an incidental sequential learning paradigm, the effects of chunking of both the presentation and response phases of performance were examined. In the first experiment, consistent stimulus chunking increased learning, and performance was at an equivalent level to this when consistent chunking of both stimuli and responses was present. Consistent chunking of the responses alone did not significantly improve learning over a baseline condition where neither stimuli nor responses were chunked. The disruption of response organization in a second experiment, through a random response condition, failed to impact learning in non-chunked and stimulus chunked conditions. A third experiment found that response chunking did benefit learning in a condition where stimuli were presented in random chunks. A final experiment suggested extended processing of the digits could not account for performance gains in the stimulus chunking condition. Overall, the results suggest that the enhanced effects of chunking on learning were stimulus-driven rather than response-driven, except under conditions that constrained a consistent pattern of stimulus organization.     

Chunking During Learning of Visuomotor Sequences with Spatial and Arbitrary Rules: Preliminary Findings

Visuomotor sequence learning requires participants to learn a two-fold process of learning the correct visuomotor transformation (spatial or arbitrary rules) and learning the correct order of performing the sequence. A motor sequence is performed with a specific timing pattern by grouping a number of elementary movements into chunks. The present research extends previous findings examining whether chunking phenomenon is observable for visuo-motor sequences with arbitrary transformations in addition to spatially defined targets. This research tests for dominant chunking patterns and individual variability.     

Infants hierarchically organize memory representations

Throughout development, working memory is subject to capacity limits that severely constrain short‐term storage. However, adults can massively expand the total amount of remembered information by grouping items into chunks. Although infants also have been shown to chunk objects in memory, little is known regarding the limits of this ability. In particular, it remains unknown whether infants can create more complex memory hierarchies, binding representations of chunks into still larger chunks in recursive fashion. Here we tested the limits of early chunking, first measuring the number of items infants can bind into a single chunk and the number of chunks infants can maintain concurrently, and then, critically, whether infants can embed chunked representations into larger units. We tested 14‐month‐old infants' memory for hidden objects using a manual search task in which we manipulated memory load (the number of objects infants saw hidden) and the chunking cues provided. We found that infants are limited in the number of items they can chunk and in the number of chunks they can remember. However, we also found that infants can bind representations of chunks into ‘superchunks’. These results suggest that hierarchically organizing information strongly affects working memory, starting in infancy.     

Learning a keying sequence you never executed: Evidence for independent associative and motor chunk learning

A substantial amount of research has addressed how people learn and control movement sequences. Recent results suggested that practice with discrete key pressing sequences results in two types of sequence learning: associative learning and motor chunk development (Verwey & Abrahamse, 2012). In the present study, we addressed whether in keying sequences of limited length associative learning develops also when the use of the chunking mode is prevented by introducing during practice random deviants. In line with the notion of two different learning mechanisms, the present results indicate that associative sequence learning develops when motor chunks cannot be developed during practice. This confirms the notion that motor chunks do not rely on these associations. In addition, experience with a particular execution mode during the practice phase seems to benefit subsequent use of that mode with unfamiliar and random sequences. Also, participants with substantial video-gaming experience were faster in executing discrete keying sequences in the chunking mode. These last two results may point to the development of a general ability to produce movement sequences in the chunking mode.     

Sequence learning by action and observation: Evidence for separate mechanisms

In the Serial Reaction Time (SRT) task, participants respond to a set of stimuli the order of which is apparently random, but which consists of repeating sub‐sequences. Participants can become sensitive to this regularity, as measured by an indirect test of reaction time, but can remain apparently unaware of the sequence, as measured by direct tests of prediction or recognition. Some researchers have claimed that this learning may take place by observation alone. We suggest that observational learning may be due to explicit acquired knowledge of the sequence, and is not mediated by the same processes which give rise to learning by action. In Expt 1, we show that it is very difficult to acquire explicit sequence knowledge under dual task conditions, even when participants are told that a regular sequence exists. In Expt 2, we use the same conditions to compare actors, who respond to the sequence during learning, and observers, who merely watch the stimuli. Furthermore, we manipulate the salience of the sequence, in order to encourage learning. There is no evidence of observational learning in these conditions, despite the usual effects of learning being demonstrated by actors. In Expt 3, we show that observational learning does occur, but only when observers have no secondary task and even then only reliably for a sequence which has been made salient by chunking subcomponents. We conclude that sequence learning by observation is mediated by explicit processes, and is eliminated under conditions which support learning by action, but make it difficult to acquire explicit knowledge.