Strategies for Generating Multiple Instances of Common and Ad Hoc Categories

Three experiments explored word/name homographs (GARLAND-musical star/ wreath of flowers) to determine the extent to which presenting them for study as surnames or as content words affected memory on immediate retest. Implicit and explicit measures were taken. Implicit memory occurred reliably on all variants of this task. Names were better remembered than words when the forename was presented as a cue and subjects were asked to generate a surname. This finding conforms with the suggestion (Bredart, Valentine, Calder, & Gassi, 1995) that there is a dedicated name-output stage in the memory system, and suggests that this can be activated under some implicit memory conditions. Further experiments showed that this name advantage was not upheld under other (word but not name) cued-recall conditions. Under these conditions, implicit memory is sensitive to the perceptual rather than the contextual conditions of presentation.     

Implicit statistical learning in language processing: Word predictability is the key

Fundamental learning abilities related to the implicit encoding of sequential structure have been postulated to underlie language acquisition and processing. However, there is very little direct evidence to date supporting such a link between implicit statistical learning and language. In three experiments using novel methods of assessing implicit learning and language abilities, we show that sensitivity to sequential structure – as measured by improvements to immediate memory span for structurally-consistent input sequences – is significantly correlated with the ability to use knowledge of word predictability to aid speech perception under degraded listening conditions. Importantly, the association remained even after controlling for participant performance on other cognitive tasks, including short-term and working memory, intelligence, attention and inhibition, and vocabulary knowledge. Thus, the evidence suggests that implicit learning abilities are essential for acquiring long-term knowledge of the sequential structure of language – i.e., knowledge of word predictability – and that individual differences on such abilities impact speech perception in everyday situations. These findings provide a new theoretical rationale linking basic learning phenomena to specific aspects of spoken language processing in adults, and may furthermore indicate new fruitful directions for investigating both typical and atypical language development.     

Processing resource capacity and the comprehension of garden path sentences

Three experiments explored the relationship between verbal working memory capacity and the comprehension of garden path sentences. In Experiment 1, subjects with high, medium, and low working memory spans made acceptability judgments about garden path and control sentences under whole sentence and rapid serial visual presentation (RSVP) conditions. There were no significant differences between subjects with different working memory spans in the comprehension of garden path sentences in either condition. In Experiments 2A and 2B, subjects with high and low working memory spans were tested on the same materials at three RSVP rates. There were no significant differences between subjects with different working memory spans in the magnitude of the effect of garden path sentences at any presentation rate. The results suggest that working memory capacity, as measured by the Daneman and Carpenter (1980) reading span task, is not a major determinant of individual differences in the processing of garden path sentences.     

Environmental context-dependent homophone spelling

Two experiments provided evidence of environmental context-dependent memory using a homophone spelling test (e.g., Jacoby & Witherspoon, 1982), an implicit, indirect measure of memory (Richardson-Klavehn & Bjork, 1988). Context reinstatement significantly increased priming in both experiments. The finding of environmental context reinstatement effects with this implicit memory test and others (Garberg & Radtke, 1986; Graf, 1988) indicates that the effect can be found reliably using a test that does not encourage subjects to generate their own context cues from memory.     

Operating characteristics of the implicit learning system supporting serial interception sequence learning

The memory system that supports implicit perceptual-motor sequence learning relies on brain regions that operate separately from the explicit, medial temporal lobe memory system. The implicit learning system therefore likely has distinct operating characteristics and information processing constraints. To attempt to identify the limits of the implicit sequence learning mechanism, participants performed the serial interception sequence learning (SISL) task with covertly embedded repeating sequences that were much longer than most previous studies: ranging from 30 to 60 (Experiment 1) and 60 to 90 (Experiment 2) items in length. Robust sequence-specific learning was observed for sequences up to 80 items in length, extending the known capacity of implicit sequence learning. In Experiment 3, 12-item repeating sequences were embedded among increasing amounts of irrelevant nonrepeating sequences (from 20 to 80% of training trials). Despite high levels of irrelevant trials, learning occurred across conditions. A comparison of learning rates across all three experiments found a surprising degree of constancy in the rate of learning regardless of sequence length or embedded noise. Sequence learning appears to be constant with the logarithm of the number of sequence repetitions practiced during training. The consistency in learning rate across experiments and conditions implies that the mechanisms supporting implicit sequence learning are not capacity-constrained by very long sequences nor adversely affected by high rates of irrelevant sequences during training.     

内隐序列学习与中央执行功能的关系

内隐序列学习与一般认知的关系一直处于争议之中。近年来,越来越多的研究显示内隐序列学习与工作记忆（尤其是中央执行功能）存在显著关联。基于此,本研究通过两个实验来探测两者的相关及机制。实验1从行为与脑电两个角度探讨经典位置序列学习与中央执行功能的相关,发现经典位置序列学习的内隐习得量与中央执行功能的抑制、刷新功能的强度呈负相关,与转换功能没有显著相关,脑电结果也支持了这一结论。实验2在内隐序列学习中加入认知冲突来增加中央执行功能的负荷。结果发现在高抑制功能负荷任务条件下,内隐习得量与抑制功能强度的相关性发生了反转,进一步证明内隐序列学习与中央执行功能的抑制子成分在脑功能上的关系：不同条件下呈现竞争、协作等不同状态。     

Hebb learning, verbal short-term memory, and the acquisition of phonological forms in children

Recent work using the Hebb effect as a marker for implicit long-term acquisition of serial order has demonstrated a functional equivalence across verbal and visuospatial short-term memory. The current study extends this observation to a sample of five- to six-year-olds using verbal and spatial immediate serial recall and also correlates the magnitude of Hebb learning with explicit measures of word and nonword paired-associate learning. Comparable Hebb effects were observed in both domains, but only nonword learning was significantly related to the magnitude of Hebb learning. Nonword learning was also independently related to individuals' general level of verbal serial recall. This suggests that vocabulary acquisition depends on both a domain-specific short-term memory system and a domain-general process of learning through repetition.     

序列位置内隐学习产生机制的实验研究

内隐学习是当今认知和学习领域继内隐记忆之后又一重要的研究课题。该研究利用序列反应时研究程式,通过两个实验,对序列位置内隐学习产生的机制进行了探讨。结果表明：（１）在序列反应时任务程式中,随着反应一刺激间隔的延长,序列位置内隐学习的学习量逐渐减少;（２）异形同模式迁移组和异形异模式迁移组被试间内隐学习量无显著差异,被试未能内隐地习得抽象的序列模式。说明序列位置内隐学习产生的基础是水平联结,在该实验条件下没有发现垂直联结存在的证据。     

Phonological and semantic strategies in immediate serial recall

It has been suggested that certain theoretically important anomalous results in the area of verbal short-term memory could be attributable to differences in strategy. However there are relatively few studies that investigate strategy directly. We describe four experiments, each involving the immediate serial recall of word sequences under baseline control conditions, or preceded by instruction to use a phonological or semantic strategy. Two experiments varied phonological similarity at a presentation rate of one item every 1 or 2 seconds. Both the control and the phonologically instructed group showed clear effects of similarity at both presentation rates, whereas these were largely absent under semantic encoding conditions. Two further experiments manipulated word length at the same two rates. The phonologically instructed groups showed clear effects at both rates, the control group showed a clear effect at the rapid rate which diminished with the slower presentation, while the semantically instructed group showed a relatively weak effect at the rate of one item per second, and a significant reverse effect with slower presentation. The latter finding is interpreted in terms of fortuitous differences in inter-item rated associability between the two otherwise matched word pools, reinforcing our conclusion that the semantically instructed group were indeed encoding semantically. Implications for controlling strategy by instruction are discussed.     

Phonological and semantic strategies in immediate serial recall

It has been suggested that certain theoretically important anomalous results in the area of verbal short-term memory could be attributable to differences in strategy. However there are relatively few studies that investigate strategy directly. We describe four experiments, each involving the immediate serial recall of word sequences under baseline control conditions, or preceded by instruction to use a phonological or semantic strategy. Two experiments varied phonological similarity at a presentation rate of one item every 1 or 2 seconds. Both the control and the phonologically instructed group showed clear effects of similarity at both presentation rates, whereas these were largely absent under semantic encoding conditions. Two further experiments manipulated word length at the same two rates. The phonologically instructed groups showed clear effects at both rates, the control group showed a clear effect at the rapid rate which diminished with the slower presentation, while the semantically instructed group showed a relatively weak effect at the rate of one item per second, and a significant reverse effect with slower presentation. The latter finding is interpreted in terms of fortuitous differences in inter-item rated associability between the two otherwise matched word pools, reinforcing our conclusion that the semantically instructed group were indeed encoding semantically. Implications for controlling strategy by instruction are discussed.     

The role of working memory capacity in implicit and explicit sequence learning of children: Differentiating movement speed and accuracy

This study investigated the role of working memory capacity on implicit and explicit motor sequence learning in young children. To this end, a task was utilized that required a gross motor response (flexing the elbow) and that could differentiate between movement speed (i.e., reaction time and movement time) and movement accuracy. Children aged 7–9 years practiced a serial reaction time task that involved the production of a fixed sequence of elbow flexions of prescribed magnitude across two consecutive days. Children in the explicit group were informed about the presence of the sequence and were shown this sequence, while children in the implicit group were not made aware of the sequence. Additionally, children's verbal and visuospatial working memory capacity was assessed. Results of day 1 regarding movement speed revealed no evidence of sequence learning for either group, but movement accuracy results suggested that sequence learning occurred for the implicit group. For both groups, only improvements in movement accuracy were consolidated on day 2, indicating both general and sequence specific learning. Working memory capacity did not correlate with learning in either of the groups. Children in the explicit group accumulated more sequence knowledge compared to children in the implicit group, but this knowledge did not translate to more or better sequence learning. The minimal differences found between the implicit and explicit condition and the absence of a role for working memory capacity add to the increasing evidence that the observed differences between implicit and explicit sequence learning in adults may be less distinct in children.     

Nonword repetition in specific language impairment: More than a phonological short-term memory deficit

The possible role of phonological short-term memory in the nonword repetition deficit of children with specific language impairment (SLI) was investigated in a study comparing serial recall and nonword repetition of sequences of auditorily presented CV syllables. The SLI group showed impairments in both serial recall and nonword repetition relative to typically developing children of the same age, however the SLI deficit in nonword repetition was greater and persisted even when differences on an independent measure of short-term memory were taken into account. These findings cannot be readily explained in terms of a sole deficit in short-term memory, and point instead to differences between the serial recall and nonword repetition paradigms as potential factors contributing to this disorder of learning.     

Individual differences in working memory capacity and learning: Evidence from the serial reaction time task

High and low working memory (WM) capacity individuals performed the serial reaction time task under both incidental and intentional learning conditions to determine the role of WM capacity in the learning of sequential information. WM capacity differences emerged in conditions of intentional but not incidental learning, indicating that individual differences in WM capacity occur in tasks requiring some form of control, with little difference appearing on tasks that required relatively automatic processing. Furthermore, an index of learning was significantly related to a measure of general fluid intelligence under intentional conditions only. Thus, the degree of learning was significantly related to higher order cognition, but only when intentional processing was emphasized.     

Implicit visual learning and the expression of learning

Although the existence of implicit motor learning is now widely accepted, the findings concerning perceptual implicit learning are ambiguous. Some researchers have observed perceptual learning whereas other authors have not. The review of the literature provides different reasons to explain this ambiguous picture, such as differences in the underlying learning processes, selective attention, or differences in the difficulty to express this knowledge. In three experiments, we investigated implicit visual learning within the original serial reaction time task. We used different response devices (keyboard vs. mouse) in order to manipulate selective attention towards response dimensions. Results showed that visual and motor sequence learning differed in terms of RT-benefits, but not in terms of the amount of knowledge assessed after training. Furthermore, visual sequence learning was modulated by selective attention. However, the findings of all three experiments suggest that selective attention did not alter implicit but rather explicit learning processes.     

The consequences of reduced memory span for the comprehension of semantic versus syntactic information

Aphasic patients with restricted memory spans were assessed on their comprehension of syntactically simple sentences varying in numbers of content words and on their comprehension of sentences matched in content words but varying in syntactic complexity. Three different presentation modes were used: unlimited visual presentation, limited visual presentation, and auditory presentation. The difference between performance in the unlimited and limited modes was used as a measure of the extent to which memory decrements caused comprehension failure. These difference scores were related to memory span in order to assess whether the memory involved in sentence processing overlaps that assessed by a memory span task. For the sentences varying in number of content words, performance was worse for the limited presentation modes than the unlimited mode, and the difference between unlimited and limited presentation modes was highly related to memory span. For the sentences varying in syntactic complexity, there was no clear reduction in performance for limited presentation modes, and the difference scores did not relate to memory span. The results support the view that the processing of sentences with many content words draws on the short-term memory capacity assessed by memory span, while the processing of syntactic complexity does not.     

Serial reaction time learning in preschool- and school-age children

Visuomotor sequence learning was assessed in 4- to 10-year-old children using a serial reaction time (SRT) task with both random and sequenced trials. One-half of the children received exposure to the sequence prior to performing the reaction time (RT) task. In Experiment 1, 7- and 10-year-old children demonstrated sequence-specific decreases in RT. As in the adult SRT literature, participants with explicit awareness of the sequence at the end of the session showed larger sequence-specific reaction time decrements than those without explicit awareness. Contrary to expectation, preexposure to the sequence did not reliably predict the level of awareness attained. Results from Experiment 2 indicate that 4-year-olds also demonstrate significant sequence learning on a variant of the SRT task. This article provides preliminary data regarding developmental changes in sequential learning and the development and use of implicit and explicit knowledge. Age-related differences emerged primarily in explicit rather than implicit knowledge.     

Recall of letters from the left and right visual half-fields under unilater and bilateral presentation.

Bilateral presentation in the visual half-field greatly increases superiority of the right visual half-field in tachistoscopic recognition of words when fixation is controlled using a center digit. Two experiments explored left-right asymmetry with bilateral presentation on a visual half-field short-term memory task, with fixation controlled by a sequence of letters at fixation. A total of 40 subjects served in the two experiments, which compared recall under unilateral versus bilateral presentation to the visual half-field. Bilateral presentation increased over-all recall from the last serial position but did not alter asymmetry of the visual half-field. As in previous experiments, the superiority of the right visual half-field was greatest from the initial serial positions. It was concluded that asymmetry of the visual half-field on this recall task with controlled fixation depends primarily on masking and short-term memory but is independent of unilateral-bilateral presentation.     

Fringe consciousness in sequence learning: the influence of individual differences

We first describe how the concept of “fringe consciousness” ([Mangan, 1993a], [Mangan, 1993b], [Mangan, 2001] and [Mangan, 2003]) can characterise gradations of consciousness between the extremes of implicit and explicit learning. We then show that the NEO-PI-R personality measure of openness to feelings, chosen to reflect the ability to introspect on fringe feelings, influences both learning and awareness in the serial reaction time (SRT) task under conditions that have previously been associated with implicit learning ([Destrebecqz and Cleeremans, 2001] and [Destrebecqz and Cleeremans, 2003]). This provides empirical evidence for the proposed phenomenology and functional role of fringe consciousness in so-called implicit learning paradigms (Mangan, 1993b). Introducing an individual difference variable also helped to identify possible limitations of the exclusion task as a measure of conscious sequence knowledge. Further exploration of individual differences in fringe awareness may help to avoid polarity in the implicit learning debate, and to resolve apparent inconsistencies between previous SRT studies.     

Processing strategies and secondary memory in very rapid forgetting

When a memory test is unexpected, recall performance is quite poor at retention intervals as short as 2–4 seconds. Orienting tasks that change encoding conditions are known to affect forgetting in such “very rapid forgetting” paradigms where people are misled to believe that recall will not be required. We evaluated the hypothesis that differences in forgetting among orienting tasks are attributable to contributions of secondary memory during encoding in two experiments. In Experiment 1, short-term recall performance was inversely related to task demands during encoding, although long-term memory performance was not. Task demands were assessed by making the duration of stimulus presentation dependent on the time required to perform three different orienting tasks. In Experiment 2, we compared performance of that variable-length stimulus presentation to the fixed-length presentation used in most prior research. The results suggested that additional encoding or rehearsal time does not have an appreciable impact on short-term performance. Thus, differences in forgetting appeared to be a function of the contribution of secondary memory rather than a function of the time available to engage in primary memory rehearsal strategies.     

不同负载条件对序列位置内隐学习的影响

序列反应时任务是继人工语法学习和复杂系统控制任务之后又一研究内隐学习的重要程式 ,该研究采用这种程式 ,比较了不同负载条件对序列位置内隐学习的影响。被试为华南师范大学本科生 6 0名。 3种负载条件分别为无负载、数字串记忆负载和反向反应负载。结果发现 ,数字记忆负载组被试与无负载组被试间内隐学习量差异显著 ,但对于不会破坏学习序列组织的反向负载组被试 ,其内隐学习量与无负载组差异不显著 ,却与数字记忆负载组间差异显著。这一结果说明序列反应时任务程式中的内隐学习不受加工容量的影响