工作记忆中注意焦点转换的代偿机制—— 来自聋生和发音抑制的证据

注意焦点转换是工作记忆中一项重要的执行功能。前人的研究提示视空间画板可能参与言语工作记忆中的注意转换。通过聋生和发音抑制方式探索语音回路子系统受损或受阻后, 视空间画板子系统完成注意转换任务的反应模式。采用“三计数”任务, 实验一比较了极重度耳聋学生和健听学生在工作记忆中的注意焦点转换效应。结果表明聋生与健听被试在不同记忆子项中转换的反应时间均长于不转换时间。但与健听被试相比, 聋生完成注意转换任务的正确率降低, 在转换和不转换之间的反应时差别减小, 且转换方向对反应时无影响, 转换方向和转换距离表现出显著的交互作用。下行转换时近转换快于远转换, 上行转换时近转换慢于远转换。实验二比较了发音抑制和无抑制条件下的注意转换效应, 发音抑制组在注意焦点转换中表现出与聋生组既类似又存在区别的反应模式。这些结果提示工作记忆的中枢执行系统具有高度的灵活性。当语音回路功能受阻后, 注意转换仍能借助视空间画板子系统得以完成。与暂时性抑制相比, 语音回路功能长期受损后表现出一定的功能代偿。     

The homophone effect in semantic access tasks using kanji words: its relation to the articulatory suppression effect

The present study examined whether articulatory suppression influences homophone effects in semantic access tasks using Japanese kanji words. In Experiment 1, participants were required to decide whether visually presented word pairs were synonyms. This experiment replicated the homophone effect observed in previous research that showed more false positive errors in response to nonsynonym homophone pairs than to controls. The present study found that this homophone effect was also obtained under an articulatory suppression condition. In Experiment 2, participants performed a semantic decision task, in which they had to judge whether a visually presented target word was an exemplar of a definition that was shown immediately before presentation of the target word. The homophone effect observed in previous studies was replicated--that is, longer response times and more false positive errors were associated with homophones of correct exemplars than with nonhomophone control words. This homophone effect was also obtained under an articulatory suppression conditions. These results suggest that the phonological processing that produces the homophone effects in semantic access tasks using Japanese kanji words does not include articulatory mechanisms.     

The homophone effect in semantic access tasks using kanji words: Its relation to the articulatory suppression effect

The present study examined whether articulatory suppression influences homophone effects in semantic access tasks using Japanese kanji words. In Experiment 1, participants were required to decide whether visually presented word pairs were synonyms. This experiment replicated the homophone effect observed in previous research that showed more false positive errors in response to nonsynonym homophone pairs than to controls. The present study found that this homophone effect was also obtained under an articulatory suppression condition. In Experiment 2, participants performed a semantic decision task, in which they had to judge whether a visually presented target word was an exemplar of a definition that was shown immediately before presentation of the target word. The homophone effect observed in previous studies was replicated—that is, longer response times and more false positive errors were associated with homophones of correct exemplars than with nonhomophone control words. This homophone effect was also obtained under an articulatory suppression conditions. These results suggest that the phonological processing that produces the homophone effects in semantic access tasks using Japanese kanji words does not include articulatory mechanisms.     

Movement and working memory: Patterns and positions in space

Five experiments are reported in which subjects were asked to remember short, visually presented sequences of whole body movement patterns, words, and spatial positions. The items were recalled in order in a memory span paradigm. During presentation of the items to be remembered subjects simply watched, or they carried out a concurrent activity involving articulatory suppression, movement to external spatial targets, or body-related movement. When the movement patterns to be remembered were familiar to subjects, movement span was not disrupted by articulatory suppression or movement to spatial targets but was disrupted by body-related movement. This movement suppression task, however, did not interfere with performance on a spatial span task or on verbal span. It is concluded that the memory for patterns of limb movement differs from memory for movement to spatial targets and that accounts of visuo-spatial processes in working memory involve the latter type of movement.     

A “word length effect”for sign language: Further evidence for the role of language in structuring working memory

We report a sign length effect in deaf users of American Sign Language that is analogous to the word length effect for speech. Lists containing long signs (signs that traverse relatively long distances) produced poorer memory performance than did lists of short signs (signs that do not change in location). Further, this length effect was eliminated by articulatory suppression (repetitive motion of the hands), and articulatory suppression produced an overall drop in performance. The pattern of results, together with previous findings (Wilson & Emmorey, 1997), provides evidence for a working memory system for sign language that consists of a phonological storage buffer and an articulatory rehearsal mechanism. This indicates a close equivalence of structure between working memory for sign language and working memory for speech. The implications of this equivalence are discussed.     

Word frequency,articulatory suppression and memory span

Watkins (1977) found memory span was longer when first and second halves of lists contained high- and low-frequency words, respectively, than when low-frequency words preceded high. One of the four experiments reported here failed to replicate this finding and found that articulatory suppression had a greater detrimental effect on span for high- than for low-frequency words. Another experiment showed that high-frequency words similar to those used by Watkins were easier to articulate than low-frequency words. In the third experiment articulatory suppression did not differentially affect delayed recall of high- and low-frequency words. The fourth experiment showed span for high- and low-frequency words was influenced in a similar way when encouraging subjects to maintain words from either early or late serial positions by articulatory rehearsal. It is concluded that differences in the strategies adopted to maintain words in the articulatory rehearsal loop can account for inconsistencies in the results obtained here and in previous experiments.     

Tactile Short-term Memory Revisited

In spite of a large body of empirical research demonstrating the importance of multisensory integration in cognition, there is still little research about multimodal encoding and maintenance effects in working memory. In this study we investigated multimodal encoding in working memory by means of an immediate serial recall task with different modality and format conditions. In a first non-verbal condition participants were presented with sequences of non-verbal inputs representing familiar (concrete) objects, either in visual, auditory or audio-visual formats. In a second verbal condition participants were presented with written, spoken, or bimodally presented words denoting the same objects represented by pictures or sounds in the non-verbal condition. The effects of articulatory suppression were assessed in both conditions. We found a bimodal superiority effect on memory span with non-verbal material, and a larger span with auditory (or bimodal) versus visual presentation with verbal material, with a significant effect of articulatory suppression in the two conditions.     

Deafness and immediate memory for pictures: dissociations between "inner speech" and the "inner ear"?

Born-deaf, orally trained youngsters were examined on two tasks of immediate memory for pictures of objects. The aim was to investigate the extent of speech coding for pictures in immediate memory in a developmental context. The deaf, unlike young hearing children, did not use picture-name rhyme spontaneously as a cue to recall in a paired association task. Nevertheless, they were just as sensitive as reading age-matched hearing controls to spoken word length in recalling pictures by name. This might mean that the deaf use articulatory rehearsal in some immediate memory tasks, but this leads to a paradoxical conclusion. What could "inner speech" in the deaf be for, if it fails to affect their "inner ear" by inducing rhyme sensitivity in the paired associate task? This paradox is discussed in relation to distinctions between covert and overt use of memory cues in the paired recall task and to possible sources of the word length effect in young hearing (8-9 years old) and deaf subjects.     

Does number data entry rely on the phonological loop?

Two experiments investigated effects of articulatory processing on number data entry. Participants entered four‐digit numbers presented as either words or numerals on a keyboard, either under an articulatory condition or in silence. In Experiment 1, the articulatory condition was articulatory suppression; in Experiment 2, it was vocalisation. In Experiment 1, the articulatory suppression group typed initial digits faster than the silent group, but for subsequent digits, the opposite pattern occurred at least with word stimuli. In Experiment 2, the silent group typed initial digits faster but typed subsequent digits somewhat slower than the vocalisation group. Thus, articulation of numbers, which promotes entry into the phonological loop of working memory, retards processing of initial digits but enhances processing of subsequent digits.     

Item identification time and rehearsal rate as predictors of memory span in children

According to the working memory model of Baddeley and Hitch (1974), the sensitivity of memory span to word length arises from the time taken to rehearse items in a speech-based “articulatory loop”. Alternatively, it has been suggested that the word-length effect may result from differences in the speed of perceptual processes of item identification. Changes in the speed of rehearsal and of item identification have also been claimed to contribute to the growth of memory span that is seen in development. In order to compare these two variables directly, groups of children aged 8 and 11 were assessed on memory span for words of one, two, and three syllables; span under articulatory suppression; rehearsal rate; and item identification time. Span was found to be a linear function of rehearsal rate across differences in both word length and age. The word-length effect was unrelated to item identification time and was diminished by articulatory suppression. These results show that the word-length effect reflects rehearsal and not item identification processes. However, the results also suggest that changes in item identification time contribute to developmental differences in span when articulation is suppressed. A distinction between item identification and rehearsal effects can be readily interpreted in terms of the working memory model if it is assumed that they indicate the efficiency of different subsystems involved in span.     

Working memory load in the initial learning phase facilitates relearning: a study of vocabulary learning

In this study, the effect of working memory load in the initial learning phase on the relearning phase was examined. Exp. 1 examined the effect of articulatory suppression in paired associative learning with a relearning method. In the learning phase, 28 participants (M age=21.8 yr., SD=2.1) learned all word-nonword associations under conditions of articulatory suppression or simple tapping. After a delay, they answered a cued recall task in a nonsuppressed condition and a relearning task in a simple tapping condition. The subjects who learned under the simple tapping condition in the learning phase required significantly more trials in the relearning phase. In Exp. 2, 28 participants (M age=20.8 yr., SD=1.5) participated, and the result was replicated. These results suggested that working memory load facilitates relearning. Results are best explained by contextual interference (Battig) rather than by the less-is-more hypothesis of Newport.     

Articulatory suppression and phonological codes in reading for meaning

The aim of this study was to investigate whether the phonological code that causes errors in printed sentence comprehension is affected by concurrent articulation. Forty adult subjects made speeded judgements of the acceptability of printed sentences. The critical sentences were foils that were (1) orthographi-cally unacceptable but phonologically acceptable (e.g. The palace had a thrown room), and (2) spelling controls that were orthographically and phonologically unacceptable (The palace had a thorns room). Half the subjects performed this task in silence (without concurrently articulating) and showed a marked phonological effect such that false alarms to phonologically acceptable foils were more frequent than false alarms to their spelling controls. The remaining subjects who performed this task with concurrent articulatory suppression showed an increase in false alarm rates, but no effect of phonology. In a control experiment using the same subjects, memory span for visually presented long and short words was measured under conditions of silence or concurrent articulation. The word length effect (Baddeley, Thomson, & Buchanan, 1975) disappeared under suppression, indicating that the suppression manipulation was highly effective. Thus the phonological codes that are used both in sentence comprehension and memory span are highly susceptible to articulatory suppression. We discuss possible relationships between phonological codes that mediate lexical access and those that support short-term verbal memory.     

Children's working memory: investigating performance limitations in complex span tasks

Three experiments investigated the roles of resource-sharing and intrinsic memory demands in complex working memory span performance in 7- and 9-year-olds. In Experiment 1, the processing complexity of arithmetic operations was varied under conditions in which processing times were equivalent. Memory span did not differ as a function of processing complexity. In Experiment 2, complex memory span was assessed under three conditions designed to vary both processing and intrinsic storage demands: mental arithmetic (significant attentional demands-requires storage), odd/even judgments (significant attentional demands-no storage required), and articulatory suppression (minimal attentional demands--no storage required). The highest memory spans were found in the articulatory suppression task. Span was at an intermediate level with arithmetic processing and was lowest for processing involving odd/even judgments. This difference in memory span for processing tasks involving arithmetic processing and odd/even judgments was eliminated in Experiment 3 when the pacing requirements of the arithmetic and odd/even processing tasks were equated. The results are consistent with the view that complex memory span performance is disrupted by processing activities that divert attentional resources from storage.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

Developmental and individual differences in visual memory span

The effects of chronological age (5+, 7+, 10+, and adult), articulatory suppression and spatial ability were assessed on three measures (recognition memory, partial recall, and free recall) of visual memory span for patterns, using a procedure devised by Wilson, Scott & Power (1987). Although span increased into adulthood for all three tasks, concurrent articulatory suppression acted to reduce span for the 10-year-old and adult subjects. The ability to generate accurate visuo-spatial representations at retrieval is perfectly well developed by 7 years of age. Speed of response was lengthened for the youngest age group, but was immune to the effects of concurrent articulatory suppression. Good spatial ability was associated with higher span estimates on all tasks, regardless of age. Whilst the data support the existence of a system for representing visual patterns, which increases in capacity with increasing chronological age, the system (or processes accessing it at retrieval) is not immune to verbal recoding strategies. The independent association of spatial ability with span is taken to imply that nonverbal encoding and/or maintenance strategies can act to boost visual span from at least 5 years of age.     

Contribution of articulatory rehearsal to short-term memory: evidence from a case of selective disruption.

We describe a brain-damaged patient with disturbed articulatory rehearsal in whom all predictions derived from a working memory model were fulfilled. The patient showed a reduced verbal span, no word-length effect on immediate recall in both the visual or the auditory modalities, no phonological similarity effect in the visual modality, and no effect of articulatory suppression. A slowed overt articulation rate provided independent evidence for disrupted articulatory rehearsal. The other components of working memory, the visuospatial scratch-pad, phonological storage system, and central executive, were functional. The selectivity of the deficit can be taken as evidence for the specific role of articulatory rehearsal in working memory.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

How grammar can cope with limited short-term memory: simultaneity and seriality in sign languages

It is known that in American Sign Language (ASL) span is shorter than in English, but this discrepancy has never been systematically investigated using other pairs of signed and spoken languages. This finding is at odds with results showing that short-term memory (STM) for signs has an internal organization similar to STM for words. Moreover, some methodological questions remain open. Thus, we measured span of deaf and matched hearing participants for Italian Sign Language (LIS) and Italian, respectively, controlling for all the possible variables that might be responsible for the discrepancy: yet, a difference in span between deaf signers and hearing speakers was found. However, the advantage of hearing subjects was removed in a visuo-spatial STM task. We attribute the source of the lower span to the internal structure of signs: indeed, unlike English (or Italian) words, signs contain both simultaneous and sequential components. Nonetheless, sign languages are fully-fledged grammatical systems, probably because the overall architecture of the grammar of signed languages reduces the STM load. Our hypothesis is that the faculty of language is dependent on STM, being however flexible enough to develop even in a relatively hostile environment.     

A visuospatial “phonological loop” in working memory: Evidence from American Sign Language

In two experiments, the question of whether working memory could support an articulatory rehearsal loop in the visuospatial domain was investigated. Deaf subjects fluent in American Sign Language (ASL) were tested on immediate serial recall. In Experiment 1, using ASL stimuli, evidence for manual motoric coding (worse recall under articulatory suppression) was found, replicating findings of ASL-based phonological coding (worse recall for phonologically similar lists). The two effects did not interact, suggesting separate components which both contribute to performance. Stimuli in Experiment 2 were namable pictures, which had to be recoded for ASL-based rehearsal to occur. Under these conditions, articulatory suppression eliminated the phonological similarity effect. Thus, an articulatory process seems to be used in translating pictures into a phonological code for memory maintenance. These results indicate a configuration of components similar to the phonological loop for speech, suggesting that working memory can develop a language-based rehearsal loop in the visuospatial modality.     

A chronometric study of mental addition in profoundly deaf children

In attempting to account for inferior mathematical attainment among deaf children of all ages, some researchers have proposed that observed deficits may be partly the result of an absence of vocalization and subvocalization in the acquisition and execution of arithmetic by the deaf. When performing mental arithmetic, hearing children, it is claimed, rely on covert counting mechanisms based on internalized speech, while their deaf counterparts, due to a lack of articulatory prowess, are unable to utilize such mechanisms and instead are forced to adopt other less effective methods based on associative retrieval of arithmetical facts from long-term memory. The present study sought to throw light on these assertions. Ten prelingually profoundly deaf 12-13-year-olds, and 10 hearing controls were required to solve the 100 simple addition combinations. Analysis of response times revealed strong similarities between the two groups, with all children appearing to employ mechanisms based on covert counting. Implications of the present results are discussed in the light of previous findings.