Articulatory rehearsal and phonological storage in working memory

The theoretical distinction between an articulatory control process and a short-term phonological store was supported in five experiments on immediate serial recall. In Experiment 1, articulatory suppression during the presentation and recall of auditory material abolished the word length effect but not the phonemic similarity effect. In Experiment 2, the two latter effects were found to be independent with auditory presentation. In Experiment 3, the effects of irrelevant speech and word length were found to be independent with visual presentation. In Experiment 4, articulatory suppression during the presentation and recall of auditory material abolished the phonemic similarity effect with a slow presentation rate. Nevertheless, in Experiment 5, articulatory suppression with a conventional presentation rate did not reduce the effect of phonemic similarity, even when a 10-sec interval was interposed between presentation and recall. These results indicate that the encoding, maintenance, and retrieval of spoken material within the phonological store do not depend on a process of articulatory rehearsal.     

Motor movement matters: The flexible abstractness of inner speech

Inner speech is typically characterized as either the activation of abstract linguistic representations or a detailed articulatory simulation that lacks only the production of sound. We present a study of the speech errors that occur during the inner recitation of tongue-twister-like phrases. Two forms of inner speech were tested: inner speech without articulatory movements and articulated (mouthed) inner speech. Although mouthing one’s inner speech could reasonably be assumed to require more articulatory planning, prominent theories assume that such planning should not affect the experience of inner speech and, consequently, the errors that are “heard” during its production. The errors occurring in articulated inner speech exhibited the phonemic similarity effect and the lexical bias effect—two speech-error phenomena that, in overt speech, have been localized to an articulatory-feature-processing level and a lexical—phonological level, respectively. In contrast, errors in unarticulated inner speech did not exhibit the phonemic similarity effect—just the lexical bias effect. The results are interpreted as support for a flexible abstraction account of inner speech. This conclusion has ramifications for the embodiment of language and speech and for the theories of speech production.     

Articulatory and Phonological Determinants of Word Length Effects in Span Tasks

Several previous studies have shown that memory span is greater for short words than for long words. This effect is claimed to occur even when the short and long words are matched for the number of syllables and phonemes and so to provide evidence for subvocal articulation as being one mechanism that underlies memory span (Baddeley, Thomson, & Buchanan, 1975). The three experiments reported in this paper further investigate the articulatory determinants of word length effects on span tasks. Experiment 1 replicated Baddeley et al.'s finding of an effect of word length on auditory and visual span when the stimuli consist of words that differ in terms of the number of syllables. Experiments 2 and 3 showed that the effects of word length are eliminated when the words in the span task are matched for the number of syllables and phonemes but differ with respect to the duration and/or complexity of their articulatory gestures. These results indicate that it is the phonological structure of a word and not features of its actual articulation that determines the magnitude of the word length effect in span tasks.     

Speech, "inner speech," and the development of short-term memory: effects of picture labeling on recall

Three experiments explored the effect of overt speech on children's use of "inner speech' in short-term memory (STM). Experiments 1 and 2 compared recall of a series of pictured objects when 5- and 11-year-olds either labeled stimuli at presentation or remained silent. Use of inner speech was assessed by manipulating word length of the picture names (Experiment 1) or phonemic similarity (Experiment 2). Word length and phonemic similarity had greater effects in the older children and when pictures were labeled at presentation. These tendencies were such that 5-year-olds were sensitive to word length and phonemic similarity only with labeling. Experiment 3 compared labeling by the child with labeling by the experimenter in 5-year-olds. There were no significant differences with respect to overall performance or effects of word length and phonemic similarity. It is suggested that speaking or listening to speech activates and internal "articulatory loop,' and that such activation is especially important when the child's ability to use inner speech in STM has not fully developed.     

Temporal Grouping Effects in Immediate Recall: A Working Memory Analysis

The presence of temporal pauses during list presentation can markedly improve immediate memory for a sequence of verbal items. A series of experiments analysed this effect using Baddeley's (1986) model of working memory. Experiment 1 showed that the effect of temporal grouping on memory for visual sequences was removed by either articulatory suppression or reciting random digits. Experiment 2 indicated that effects of temporal grouping were insensitive to the word length of the items. Experiment 3 showed that articulatory suppression did not remove the temporal grouping effect for auditory lists. Experiment 4 showed that the temporal grouping effect was insensitive to the phonemic similarity of the items. The effects of concurrent articulation suggest that grouping influences the phonological loop component of working memory. However, the working memory model is insufficiently well specified to account for the insensitivity of grouping effects to word length and phonemic similarity. The main findings could be simulated by a connectionist model of the phonological loop, which invokes a context timing signal (Burgess & Hitch, 1992, in press), This assumed that pauses during list presentation affect the timing signal in a similar way to the pause before list presentation and made some novel predictions.     

Articulatory drift in the speech of children with articulation and phonological disorders

This study used electropalatography to identify articulatory drift in alveolar stops (/t/ and /d/) produced by 10 children with functional articulation and phonological disorders. Drift involves an abnormal change in place of articulation that occurs during stop closure. An index was used to measure drift, with higher values indicating greater drift. The results showed that drift was higher for children who produced undifferentiated gestures (articulations with increased tongue-palate contact). Drift is an important characteristic of articulation because it is believed to reflect impaired speech motor control. In addition, drift could explain some perceptually based speech errors that are frequently reported in functional disorders.     

Neural correlates in the processing of phoneme-level complexity in vowel production

We investigated how articulatory complexity at the phoneme level is manifested neurobiologically in an overt production task. fMRI images were acquired from young Korean-speaking adults as they pronounced bisyllabic pseudowords in which we manipulated phonological complexity defined in terms of vowel duration and instability (viz., COMPLEX: /ti?i/ >> MID-COMPLEX: /tiye/ >> SIMPLE: /tii/). Increased activity in the left inferior frontal gyrus (Brodmann Areas (BA) 44 and 47), supplementary motor area and anterior insula was observed for the articulation of COMPLEX sequences relative to MID-COMPLEX; this was the case with the articulation of MID-COMPLEX relative to SIMPLE, except that the pars orbitalis (BA 47) was dominantly identified in the Broca’s area. The differentiation indicates that phonological complexity is reflected in the neural processing of distinct phonemic representations, both by recruiting brain regions associated with retrieval of phonological information from memory and via articulatory rehearsal for the production of COMPLEX vowels. In addition, the finding that increased complexity engages greater areas of the brain suggests that brain activation can be a neurobiological measure of articulo-phonological complexity, complementing, if not substituting for, biomechanical measurements of speech motor activity.     

工作记忆中的语音回路对汉语阅读理解的影响

语音回路是工作记忆中一个重要的组成部分,主要负责加工和存储语音信息。采用混合实验设计,以正确数和反应时 为指标,汉语语篇为阅读材料,探讨工作记忆中的语音回路对汉语阅读理解的影响。本研究包括两个实验,实验一采用发音抑制的范式,结合错误干扰考察了语音回路中的发音复述装置对汉语阅读理解的影响;实验二采用无关言语的范式,结合错误干扰考察了语音回路中的语音存储装置对汉语阅读理解的影响。结果表明：(1)通过发音抑制和无关言语的方法证明,语音回路中的发音复述装置和语音存储装置在汉语阅读理解中起着重要作用。(2) 字音和字形都影响汉语的阅读理解,但字形比字音起着更大的作用,而且它们的作用机制也不相同,字音直接进入语音存储装置,而字形要经过字音的转换进入语音存储装置。(3) 词频与语音回路有密切关系,语音回路中的发音复述装置的作用在高频词上有明显的表现。(4) 词频与字形、字音也有密切关系,在低频词的条件下,字形的作用大于字音的作用     

Developing the theory of working memory

The theory of working memory was devised to explain the effects of a concurrent memory load in various experimental situations in terms of the operation of a central executive processor and a phonemic response buffer. It also explains the effects of phonemic similarity, articulatory suppression, word length, and unattended speech. Experiment 1 demonstrated that a concurrent memory load markedly reduced the phonemic similarity effect in immediate serial recall, which was taken to support the concept of a limited-capacity phonemic response buffer. A more detailed analysis of the results suggested that a concurrent memory load may affect the storage capacity of the central executive processor and the translation of orthographic stimuli into phonological representations, as well as the storage capacity of the phonemic response buffer. Experiment 2 showed that a concurrent free-recall task reduced the phonemic similarity effect in immediate serial recall, but only in the case of visually presented sequences of items. Moreover, unattended speech was found to have no effect upon performance in immediate free recall. These results were taken to imply that the phonemic response buffer contributes only to performance in cognitive tasks that require the accurate retention of serial-order information.     

Articulatory coding and phonological judgements on written words and pictures: The role of the phonological output buffer

Abstract

The ability of Italian subjects to make phonological judgements was investigated in three experiments. The judgements comprised initial sound similarity and stress assignment on pain of both written words and pictures. Stress assignment on both words and pictures as well as initial sound similarity on pictures required the activation of phonological lexical representations, but this was not necessarily the case for initial sound similarity judgements on word pairs. The first study assessed the effects of concurrent articulatory suppression on the judgements. Experiment 2 used a concomitant task (chewing), which shares with suppression the use of articulatory components but does not involve speech programming and production. The third experiment investigated the effects of unattended speech on the phonological judgements. The results of these three experiments showed that articulatory suppression had a significant disrupting effect on accuracy in all four conditions, while neither articulatory non-speech (chewing) or unattended auditory speech had any effect on the subjects' performance. The results suggest that these phonological judgements involve the operation of an articulatory speech output component, which is not implemented peripherally and does not require the involvement of a non-articulatory input system.     

Neuromagnetic evidence for a featural distinction of English consonants: sensor- and source-space data

Speech sounds can be classified on the basis of their underlying articulators or on the basis of the acoustic characteristics resulting from particular articulatory positions. Research in speech perception suggests that distinctive features are based on both articulatory and acoustic information. In recent years, neuroelectric and neuromagnetic investigations provided evidence for the brain's early sensitivity to distinctive features and their acoustic consequences, particularly for place of articulation distinctions. Here, we compare English consonants in a Mismatch Field design across two broad and distinct places of articulation - labial and coronal - and provide further evidence that early evoked auditory responses are sensitive to these features. We further add to the findings of asymmetric consonant processing, although we do not find support for coronal underspecification. Labial glides (Experiment 1) and fricatives (Experiment 2) elicited larger Mismatch responses than their coronal counterparts. Interestingly, their M100 dipoles differed along the anterior/posterior dimension in the auditory cortex that has previously been found to spatially reflect place of articulation differences. Our results are discussed with respect to acoustic and articulatory bases of featural speech sound classifications and with respect to a model that maps distinctive phonetic features onto long-term representations of speech sounds.     

Disruption of verbal STM by irrelevant speech, articulatory suppression, and manual tapping: Do they have a common source?

Under appropriate conditions, immediate serial verbal recall is impaired by irrelevant speech, articulatory suppression, and syncopated tapping. Interpretation of these variables in terms of the phonological loop component of working memory assumes separate phonological storage and articulatory rehearsal processes. In contrast, the Object-Oriented Episodic Record (O-OER) of Jones and the feature theory of Neath interpret these and other phenomena in terms of a unitary multimodal system. Three experiments investigate these disrupting tasks, with each experiment emphasizing one parameter. In each case, recall of phonologically similar and dissimilar letter sequences is compared as a marker of the presence or absence of phonological coding. In Experiment 1, subjects heard or articulated a single item, or tapped a single key at equal intervals. Only articulatory suppression impaired performance; it also abolished the effects of phonological similarity. Experiment 2 was identical, except that items were heard, or generated in a syncopated rhythm. Both suppression and tapping impaired performance to an equivalent extent and obliterated the effect of phonological similarity. Syncopated irrelevant speech caused a modest but significant impairment in performance. Experiment 3 was identical to Experiment 1, except that six tokens were used. Irrelevant speech and tapping had a clear impact on recall, but neither removed the phonological similarity effect. Again articulatory suppression had a major impact on performance and removed the effect of phonological similarity. We conclude that the pattern of results readily fits the phonological loop hypothesis, provided one accepts Saito's proposal that generating syncopated sequences uses common processes with speech production. It is not clear how the results can be explained by either the O-OER or the feature hypothesis.     

Unimpaired short-term memory and rhyme judgement in congenitally speechless individuals: Implications for the notion of “articulatory coding”

In normal adults, concurrent articulation impairs short-term memory, abolishing both the phonological similarity effect and the word length effect when visual presentation is used. It also interferes with ability to judge whether visually presented words rhyme. It is generally assumed that concurrent articulation impairs performance because it prevents people from recoding material into an articulatory form. If this is the explanation, then individuals who are congenitally speechless (anarthric) or speech-impaired (dysarthric) should show the same impairments as normal individuals who are concurrently articulating—i.e. they should have reduced memory spans, fail to show word length and phonological similarity effects in short-term memory, and find rhyme judgement difficult. These predictions were tested in a study of 48 cerebral palsied individuals: 12 anarthric, 12 dysarthric, and 24 controls individually matched to the speech-impaired subjects. There was no impairment of memory span in speech-impaired subjects, who showed normal phonological similarity and word-length effects in short-term memory. Speech-impaired subjects did not differ from their controls in ability to tell whether names of pairs of pictures rhymed. These results challenge the notion that “articulatory coding” is implicated in short-term memory and rhyme judgement and suggests that processes such as rehearsal and phonemic segmentation involve generation of a more abstract central phonological code.     

Similarities between the irrelevant sound effect and the suffix effect

Although articulatory suppression abolishes the effect of irrelevant sound (ISE) on serial recall when sequences are presented visually, the effect persists with auditory presentation of list items. Two experiments were designed to test the claim that, when articulation is suppressed, the effect of irrelevant sound on the retention of auditory lists resembles a suffix effect. A suffix is a spoken word that immediately follows the final item in a list. Even though participants are told to ignore it, the suffix impairs serial recall of auditory lists. In Experiment 1, the irrelevant sound consisted of instrumental music. The music generated a significant ISE that was abolished by articulatory suppression. It therefore appears that, when articulation is suppressed, irrelevant sound must contain speech for it to have any effect on recall. This is consistent with what is known about the suffix effect. In Experiment 2, the effect of irrelevant sound under articulatory suppression was greater when the irrelevant sound was spoken by the same voice that presented the list items. This outcome is again consistent with the known characteristics of the suffix effect. It therefore appears that, when rehearsal is suppressed, irrelevant sound disrupts the acoustic-perceptual encoding of auditorily presented list items. There is no evidence that the persistence of the ISE under suppression is a result of interference to the representation of list items in a postcategorical phonological store.     

Phonological and articulatory impairment in Alzheimer's disease: a case series

We demonstrate that phonological and articulatory impairments may occur at presentation or early in the course of Alzheimer's disease, contrary to claims that these aspects of language production are relatively preserved until the final stages of this disease. Six patients with pathologically confirmed Alzheimer's disease (AD) and four patients with clinically diagnosed dementia of the Alzheimer's type (DAT) presented with one of five different clinical profiles: nonfluent progressive aphasia, mixed progressive aphasia, progressive aphasia diagnosed as DAT from neuropsychological assessment, initial amnestic syndrome with prominent phonological errors, and biparietal syndrome. Analysis of their conversational speech, single-word production, and performance of highly familiar series speech tasks such as counting revealed false start errors, phonological paraphasias, and/or articulatory difficulty. Neuropathological changes were located in left perisylvian regions consistent with speech and language impairment but atypical for Alzheimer's disease.     

The phonological store of working memory: is it phonological and is it a store?

The phonological store construct of the working memory model is critically evaluated. Three experiments test the prediction that the effect of irrelevant sound and the effect of phonological similarity each survive the action of articulatory suppression but only when presentation of to-be-remembered lists is auditory, not visual. No evidence was found to support the interaction predicted among irrelevant speech, modality, and articulatory suppression. Although evidence for an interaction among modality, phonological similarity, and articulatory suppression was found, its presence could be diminished by a suffix, which is an acoustic, not a phonological factor. Coupled with other evidence--from the irrelevant sound effect and errors in natural speech--the action attributed to the phonological store seems better described in terms of a combination of auditory-perceptual and output planning mechanisms.     

The role of articulation in the parsing and retention of letter strings in tachistoscopic free recall

In Mewhort and Campbell's (1981) model of visual word recognition, a scan-parse mechanism transfer information from a character buffer to a short-term store and is largely responsible for the familiarity effects observed in tachistoscopic free recall. Although Mewhort and Campbell do not elaborate on the role of articulation in this task, they do suggest that the scan-parse mechanism acts prior to any involvement of articulatory processes (see Mewhort & Campbell, 1980). However, proponents of working memory (see Baddeley, 1986) are clear that articulation is necessary for the transfer of visual information to a phonological short-term store. In order to clarify the role of articulation in the parsing and retention of letter string, we asked subjects to undertake a tachistoscopic free-recall task, involving first- and fourth-order letter strings, with and without articulatory suppression and/or unattended speech. Unattended speech was observed to interfere with recall, but only when subjects were free to articulate the strings. This implies that subjects were retrieving information from the phonological store and that articulation is necessary for the registration of visual information in this store. The lack of interaction between order-of-approximation and suppression supports the view that the scan-parse mechanism acts independently of articulation. It appears, therefore, that letter strings are parsed at a stage preceding their transfer of the pharmacological store. Finally, the results indicate that subjects are able to draw directly on a representation of the parsed components of a letter string and may do so when phonological storage is difficult.(ABSTRACT TRUNCATED AT 250 WORDS)     

Contrasting speech patterns in apraxia of speech and phonemic paraphasia

This study was designed to determine if perceptual phonological analysis would reveal distinctions between patients with apraxia of speech and patients with phonemic paraphasic speech. Test findings from 10 Broca's aphasics with apraxia of speech were compared to findings from 10 paraphasic speakers (5 conduction and 5 Wernicke's aphasics). Several marked differences were revealed. Predominant locus of errors and relative difficulty of different classes of phonemic segments were significant discriminators. There was a nonsignificant trend for substituted phonemes to be further from target phonetically in the paraphasic patients. In addition, the two groups showed certain consistent differences in the types of errors they produced. Apraxic patients produced many errors of transitionalization, while sequencing errors were more typical of the patients with phonemic paraphasia. The findings are interpreted in relation to a neuropsychological model of speech. It is suggested that phonemic paraphasia represents a breakdown mainly in the retrieval of phonological word patterns, while apraxia of speech is characterized predominantly by a disturbance in encoding phonological patterns into appropriate speech movements.     

The role of subvocalisation in reading

A series of experiments explored the role of subvocalisation in fluent reading. Experiment I showed that when subjects were required to suppress articulation while reading, their ability to detect anomalous words or errors of word order in prose was markedly impaired although speed of reading was unaffected. Experiment II showed that this decrement was not a general effect due to performing a secondary task, since a concurrent tapping task did not impair detection accuracy. A third study explored the role of acoustic interference in reading by requiring subjects to detect errors in prose while attempting to ignore irrelevant speech, with or without articulatory suppression. Once again articulatory suppression led to a clear decrement in the subject's ability to detect errors, while unattended speech had no effect on performance. None of the manipulations influenced the speed with which the subjects performed the reading task. It is concluded that subvocalisation allows the creation of a supplementary articulatory code which is produced and utilised in parallel with other aspects of reading. Such a code seems particularly suitable for monitoring order information.     

Hearing lips in a second language: visual articulatory information enables the perception of second language sounds

We investigated the effects of visual speech information (articulatory gestures) on the perception of second language (L2) sounds. Previous studies have demonstrated that listeners often fail to hear the difference between certain non-native phonemic contrasts, such as in the case of Spanish native speakers regarding the Catalan sounds /ɛ/ and /e/. Here, we tested whether adding visual information about the articulatory gestures (i.e., lip movements) could enhance this perceptual ability. We found that, for auditory-only presentations, Spanish-dominant bilinguals failed to show sensitivity to the /ɛ/–/e/ contrast, whereas Catalan-dominant bilinguals did. Yet, when the same speech events were presented audiovisually, Spanish-dominants (as well as Catalan-dominants) were sensitive to the phonemic contrast. Finally, when the stimuli were presented only visually (in the absence of sound), none of the two groups presented clear signs of discrimination. Our results suggest that visual speech gestures enhance second language perception at the level of phonological processing especially by way of multisensory integration.