Short-term memory errors for spoken syllables are affected by the linguistic structure of the syllables

Exploring the necessary conditions for phonological interference in serial recall

This paper explores the impact of phonological overlap amongst items on short term memory recall performance by manipulating the type, number and syllabic position of shared phonemes between words in a serial recall task. Roodenrys et al [Roodenrys, S., Miller., L. M., & Josifoski, N. (2022b). Phonemic interference in short-term memory contributes to forgetting but it is not due to overwriting. Journal of Memory and Language, 122, 104301. https://doi.org/10.1016/j.jml.2021.104301] demonstrated that when the phonemes of a target word also occur in words earlier in the list, recall of the target word is impaired. Two experiments are reported that further examine the nature of this interference effect. Experiment 1 varied the type and number of phonemes shared with the single syllable target word by other list words and found a single shared vowel impaired target word recall performance as much as two shared consonants. Experiment 2 altered the syllabic position of the overlapping phonemes and found shared syllabic position was necessary to impair recall of the target word. It is argued these results show that not all phonological overlap is equally detrimental and specific psycholinguistic conditions are necessary to produce interference that impairs recall performance.

Taxonomic Interference Associated with Phonemic Paraphasias in Agrammatic Primary Progressive Aphasia

Phonemic paraphasias are thought to reflect phonological (post-semantic) deficits in language production. Here we present evidence that phonemic paraphasias in non-semantic primary progressive aphasia (PPA) may be associated with taxonomic interference. Agrammatic and logopenic PPA patients and control participants performed a word-to-picture visual search task where they matched a stimulus noun to 1 of 16 object pictures as their eye movements were recorded. Participants were subsequently asked to name the same items. We measured taxonomic interference (ratio of time spent viewing related vs. unrelated foils) during the search task for each item. Target items that elicited a phonemic paraphasia during object naming elicited increased taxonomic interference during the search task in agrammatic but not logopenic PPA patients. These results could reflect either very subtle sub-clinical semantic distortions of word representations or partial degradation of specific phonological word forms in agrammatic PPA during both word-to-picture matching (input stage) and picture naming (output stage). The mechanism for phonemic paraphasias in logopenic patients seems to be different and to be operative at the pre-articulatory stage of phonological retrieval. Glucose metabolic imaging suggests that degeneration in the left posterior frontal lobe and left temporo-parietal junction, respectively, might underlie these different patterns of phonemic paraphasia.

Working Memory in the Acquisition of Vocabulary and Syntax: Putting Language in Good Order

This paper argues that working memory is heavily involved in language acquisition as (a) a major part of language learning is the learning of sequences, (b) working memory allows short-term maintenance of sequence information, and (c) short-term rehearsal of sequences promotes the consolidation of long-term memories of language sequences. It first reviews evidence supporting this position. Next it presents an experiment that demonstrates that subjects encouraged to rehearse foreign language (FL) utterances are better than both silent controls and subjects who are prevented from rehearsal by articulatory suppression at (a) learning to comprehend and translate FL words and phrases, (b) explicit metalinguistic knowledge of the detailed content of grammatical regularities, (c) acquisition of the FL forms of words and phrases, (d) accuracy in FL pronunciation, and (e) some aspects of productive (but not receptive) grammatical fluency and accuracy. Finally, it describes possible mechanisms underlying these effects.

Orthographic Rime Priming

Three experiments are described, each using a partial priming technique in which a target word was briefly preceded by a masked trigram. The relative strength of priming effects was assessed by comparing the difference in target word naming times between unprimed and primed trials in different priming conditions. Experiment 1 replicated previous work in demonstrating stronger priming when the target word was primed by the orthographic rime than when the prime constituted otherwise comparable word-final trigrams that do not constitute orthographic rimes. Experiment 2 compared orthographic, phonological rime, and control primes. Only orthographic rime primes reliably increased target word naming speed, although the priming effect was less selective with longer prime durations. In Experiment 3 priming was observed for both orthographic rime and phonological rime primes shown for 150 msec. However, stronger priming was observed with orthographic rime primes. These experiments demonstrate that orthographic rime priming effects do not simply reflect the activation of an intact subunit of the target word articulation program.

Language repetition and short-term memory: an integrative framework

Short-term maintenance of verbal information is a core factor of language repetition, especially when reproducing multiple or unfamiliar stimuli. Many models of language processing locate the verbal short-term maintenance function in the left posterior superior temporo-parietal area and its connections with the inferior frontal gyrus. However, research in the field of short-term memory has implicated bilateral fronto-parietal networks, involved in attention and serial order processing, as being critical for the maintenance and reproduction of verbal sequences. We present here an integrative framework aimed at bridging research in the language processing and short-term memory fields. This framework considers verbal short-term maintenance as an emergent function resulting from synchronized and integrated activation in dorsal and ventral language processing networks as well as fronto-parietal attention and serial order processing networks. To-be-maintained item representations are temporarily activated in the dorsal and ventral language processing networks, novel phoneme and word serial order information is proposed to be maintained via a right fronto-parietal serial order processing network, and activation in these different networks is proposed to be coordinated and maintained via a left fronto-parietal attention processing network. This framework provides new perspectives for our understanding of information maintenance at the non-word-, word- and sentence-level as well as of verbal maintenance deficits in case of brain injury.

A semantic contribution to nonword recall? Evidence for intact phonological processes in semantic dementia

Patients with semantic dementia make numerous phonological errors in their immediate serial recall of words that they understand poorly. Previous studies have argued that these errors result from a reduction in the normal contribution made by semantics to the coherence of items in the phonological system. It is possible, however, that the errors might reflect additional subtle phonological deficits. Six patients with semantic dementia were tested on a variety of phonological processing and short-term memory tasks, in order to explore these possibilities. For the most part, the patients showed normal performance in phonological awareness and discrimination tasks and normal effects of phonological similarity and word length in immediate serial recall. The more severely impaired patients, however, showed some weakness on tests of nonword repetition and recall. Every patient showed better recall of words that were still relatively well understood, compared with words that were more semantically degraded. This difference extended to nonwords that were phonologically similar to the known and degraded words, suggesting that the patients' semantic deficits could account for their impairments in nonword recall. The recall advantage for semantically known over degraded items also extended to a nonverbal delayed picture copying task, suggesting that the patients' immediate serial recall impairments were underpinned by a central semantic deficit, and not by a separable lexical deficit.

Strong and long: Effects of word length on phonological binding in verbal short-term memory

This study examined the effects of item length on the contribution of linguistic knowledge to immediate serial recall (ISR). Long words are typically recalled more poorly than short words, reflecting the greater demands that they place on phonological encoding, rehearsal, and production. However, reverse word length effects—that is, better recall of long than short words—can also occur in situations in which phonological maintenance is difficult, suggesting that long words derive greater support from long-term lexical knowledge. In this study, long and short words and nonwords (containing one vs. three syllables) were presented for immediate serial recall in (a) pure lists and (b) unpredictable mixed lists of words and nonwords. The mixed-list paradigm is known to disrupt the phonological stability of words, encouraging their phonemes to recombine with the elements of other list items. In this situation, standard length effects were seen for nonwords, while length effects for words were absent or reversed. A detailed error analysis revealed that long words were more robust to the mixed-list manipulation than short words: Their phonemes were less likely to be omitted and to recombine with phonemes from other list items. These findings support an interactive view of short-term memory, in which long words derive greater benefits from lexical knowledge than short words—especially when their phonological integrity is challenged by the inclusion of nonwords in mixed lists.

Understanding Phoneme Segmentation Performance by Analyzing Abilities and Word Properties

Several studies have demonstrated the relationship between phoneme segmentation ability and early reading performance, but so far it is unclear which abilities are involved, and which word properties contribute to the difficulty level of a segmentation task. Using a sample of 596 Dutch children, we investigated the abilities involved in segmenting the phonemes of 45 pseudowords that differed with respect to several properties. First, we found that a combination of short-term memory and speech perception explained variation in segmentation performance. Second, we found that a limited number of word property effects explained the difficulty level of pseudowords rather well. Finally, we constructed a high-reliability scale for measuring segmentation ability.

Neural representations and mechanisms for the performance of simple speech sequences

Speakers plan the phonological content of their utterances before their release as speech motor acts. Using a finite alphabet of learned phonemes and a relatively small number of syllable structures, speakers are able to rapidly plan and produce arbitrary syllable sequences that fall within the rules of their language. The class of computational models of sequence planning and performance termed competitive queuing models have followed K. S. Lashley [The problem of serial order in behavior. In L. A. Jeffress (Ed.), Cerebral mechanisms in behavior (pp. 112-136). New York: Wiley, 1951] in assuming that inherently parallel neural representations underlie serial action, and this idea is increasingly supported by experimental evidence. In this article, we developed a neural model that extends the existing DIVA model of speech production in two complementary ways. The new model includes paired structure and content subsystems [cf. MacNeilage, P. F. The frame/content theory of evolution of speech production. Behavioral and Brain Sciences, 21, 499-511, 1998 ] that provide parallel representations of a forthcoming speech plan as well as mechanisms for interfacing these phonological planning representations with learned sensorimotor programs to enable stepping through multisyllabic speech plans. On the basis of previous reports, the model's components are hypothesized to be localized to specific cortical and subcortical structures, including the left inferior frontal sulcus, the medial premotor cortex, the basal ganglia, and the thalamus. The new model, called gradient order DIVA, thus fills a void in current speech research by providing formal mechanistic hypotheses about both phonological and phonetic processes that are grounded by neuroanatomy and physiology. This framework also generates predictions that can be tested in future neuroimaging and clinical case studies.

The relation between content and structure in language production: an analysis of speech errors in semantic dementia

In order to explore the impact of a degraded semantic system on the structure of language production, we analysed transcripts from autobiographical memory interviews to identify naturally-occurring speech errors by eight patients with semantic dementia (SD) and eight age-matched normal speakers. Relative to controls, patients were significantly more likely to (a) substitute and omit open class words, (b) substitute (but not omit) closed class words, (c) substitute incorrect complex morphological forms and (d) produce semantically and/or syntactically anomalous sentences. Phonological errors were scarce in both groups. The study confirms previous evidence of SD patients' problems with open class content words which are replaced by higher frequency, less specific terms. It presents the first evidence that SD patients have problems with closed class items and make syntactic as well as semantic speech errors, although these grammatical abnormalities are mostly subtle rather than gross. The results can be explained by the semantic deficit which disrupts the representation of a pre-verbal message, lexical retrieval and the early stages of grammatical encoding.

Visual speech primes open-set recognition of spoken words

Visual speech perception has become a topic of considerable interest to speech researchers. Previous research has demonstrated that perceivers neurally encode and use speech information from the visual modality, and this information has been found to facilitate spoken word recognition in tasks such as lexical decision (Kim, Davis, & Krins, 2004). In this paper, we used a cross-modality repetition priming paradigm with visual speech lexical primes and auditory lexical targets to explore the nature of this priming effect. First, we report that participants identified spoken words mixed with noise more accurately when the words were preceded by a visual speech prime of the same word compared with a control condition. Second, analyses of the responses indicated that both correct and incorrect responses were constrained by the visual speech information in the prime. These complementary results suggest that the visual speech primes have an effect on lexical access by increasing the likelihood that words with certain phonetic properties are selected. Third, we found that the cross-modality repetition priming effect was maintained even when visual and auditory signals came from different speakers, and thus different instances of the same lexical item. We discuss implications of these results for current theories of speech perception.

Lexical coherence in short-term memory: strategic reconstruction or "semantic glue"?

This study explores the foundation of lexical/semantic phoneme binding effects in verbal short-term memory (STM). The immediate serial recall of pure lists of words and nonwords was compared with the recall of mixed lists that had either a predictable, alternating structure (e.g., wnwnwn) or an unpredictable structure (i.e., the serial positions of the words/nonwords could not be known in advance). The study provides evidence for two separate mechanisms by which long-term linguistic knowledge contributes to STM. First, there was evidence for automatic lexical/semantic binding effects that were independent of knowledge of lexical status. The nonwords in both types of mixed list damaged word recall and encouraged the phonological elements of words to migrate. In both alternating and unpredictable mixed lists, the phonemes of words were more likely than the phonemes of nonwords to be recalled together as a coherent item, suggesting that lexical/semantic knowledge encourages the phonological elements of words to emerge together in immediate serial recall, even when lexical status is unknown. Secondly, there was evidence for "strategic redintegration", which was dependent on prior knowledge of the lexical status of the items in mixed lists. When participants recalled items that they knew to be words in advance, they were able to use this knowledge to constrain their responses so that they were more likely to be lexically appropriate. These findings motivate modifications to current theories of the interaction between linguistic knowledge and verbal short-term memory.

Multisyllabic nonwords: more than a string of syllables

Nonword repetition is closely associated with the learning of the phonological form of novel words. Several factors influence nonword repetition performance such as short-term memory, phonotactic probability, lexical knowledge, and prosodic factors. The present study examined the influence of list duration, coarticulation, and prosody on nonword repetition by comparing naturally articulated multisyllabic nonwords to multisyllabic nonwords formed by concatenating syllables produced in isolation and serial lists (experiment 1), to multisyllabic forms that incorporated either valid or invalid coarticulatory information (experiment 2), and to multisyllabic forms either with or without common English within-word stress patterns (experiment 3). Results revealed superior recall for naturally articulated nonwords compared to lists of matched duration or sequences with invalid coarticulatory cues. Within-word stress patterns also conveyed a repetition advantage. The findings clearly establish that the coarticulatory and prosodic cues of naturally articulated multisyllabic forms support retention.

Verbal working memory and language production: Common approaches to the serial ordering of verbal information

Verbal working memory (WM) tasks typically involve the language production architecture for recall; however, language production processes have had a minimal role in theorizing about WM. A framework for understanding verbal WM results is presented here. In this framework, domain-specific mechanisms for serial ordering in verbal WM are provided by the language production architecture, in which positional, lexical, and phonological similarity constraints are highly similar to those identified in the WM literature. These behavioral similarities are paralleled in computational modeling of serial ordering in both fields. The role of long-term learning in serial ordering performance is emphasized, in contrast to some models of verbal WM. Classic WM findings are discussed in terms of the language production architecture. The integration of principles from both fields illuminates the maintenance and ordering mechanisms for verbal information.

Investigating the roles of phonological and semantic memory in sentence recall

The mechanisms underlying short-term sentence recall have been the subject of recent investigations. While both semantic and phonological information have been found to play a role in sentence recall, this has been established using different paradigms in previous research. As a result, it is not clear whether the contributions of semantic and phonological information are equivalent subject only to specific experimental conditions. The present study used a common paradigm with equally plausible lures to systematically compare the roles of semantic and phonological information in short-term sentence recall. The lure intrusion paradigm was used with three different lures that were all equally plausible in the context of the sentence: semantic, onset, and rhyme. Further, no contextual cues were provided in the sentence to bias the participant. The findings indicate that there were significantly more semantic and onset intrusions compared to rhyme intrusions. This is interpreted in light of models incorporating lexical information during sentence production.

The functional unit in phonological encoding: evidence for moraic representation in native Japanese speakers

Speech production studies have shown that the phonological form of a word is made up of phonemic segments in stress-timed languages (e.g., Dutch) and of syllables in syllable-timed languages (e.g., Chinese). To clarify the functional unit of mora-timed languages, the authors asked native Japanese speakers to perform an implicit priming task (A. S. Meyer, 1990, 1991). In Experiment 1, participants could speed up their production latencies when initial consonant and vowel (CV) of a target word were known in advance but failed to do so when the vowel was unknown. In Experiment 2, prior knowledge of the consonant and glide (Cj) produced no significant priming effect. However, in Experiment 3, significant effects were found for the consonant-vowel coupled with a nasal coda (CVN) and the consonant with a diphthong (CVV), compared with the consonant-vowel alone (CV). These results suggest that the implicit priming effects for Japanese are closely related to the CV-C and CV-V structure, called the mora. The authors discuss cross-linguistic differences in the phonological representation involved in phonological encoding, within current theories of word production.

Lexical and semantic influences on item and order memory in immediate serial recognition: evidence from a novel task

Previous studies have reported that, in contrast to the effect on immediate serial recall, lexical/semantic factors have little effect on immediate serial recognition. This has been taken as evidence that linguistic knowledge contributes to verbal short-term memory in a redintegrative process at recall. Contrary to this view, we found that lexicality, frequency, and imageability all influenced matching span. The standard matching span task, requiring changes in item order to be detected, was less susceptible to lexical/semantic factors than was a novel task involving the detection of phoneme order and hence item identity changes. Therefore, in both immediate recognition and immediate serial recall, lexical/semantic knowledge makes a greater contribution to item identity than to item order memory. Task sensitivity, and not the absence of overt recall, may have underpinned previous failures to show effects of these variables in immediate recognition. We also compared matching span for pure and unpredictable mixed lists of words and nonwords. Lexicality had a larger impact on immediate recognition for pure than for mixed lists, in line with findings for immediate serial recall. List composition affected the detection of phoneme but not item order changes in matching span; similarly, in recall, mixed lists produce more frequent word phoneme migrations but not migrations of entire items. These results point to strong similarities between immediate serial recall and recognition. Lexical/semantic knowledge may contribute to phonological stability in both tasks.

The influence of phoneme position overlap on the phonemic similarity effect in nonword recall

The current research examined the predictions that short-term memory models generate for the phonological similarity effect, when similarity was defined in different ways. Three serial recall experiments with consonant–vowel–consonant (CVC) nonwords are reported, where the position of the phonemes that list items shared was manipulated (i.e., shared vowel and final consonant [_VC; Experiment 1], initial consonant and vowel [CV_; Experiment 2], or the two consonants [C_C; Experiment 3]. The results show that the position of common phonemes in nonwords has differential effects on order and item information. The findings are discussed in relation to previous research into the effect of phonemic similarity on nonword recall, and modifications to current short-term memory models are proposed.

Rhyming words and onset–rime constituents: An inquiry into structural breaking points and emergent boundaries in the syllable

Geudens and Sandra, in their 2003 study, investigated the special role of onsets and rimes in Dutch-speaking children's explicit phonological awareness. In the current study, we tapped implicit phonological knowledge using forced-choice similarity judgment (Experiment 1) and recall of syllable lists (Experiment 2). In Experiment 1, Dutch-speaking prereaders judged rime-sharing pseudowords (/fas/-/mas/) to sound more similar than pseudowords sharing an equally sized nonrime unit (/fas/-/fak/). However, in a syllable recall task (/tepsilonf/, /ris/, /nal/), Dutch-speaking prereaders were as likely to produce recombination errors that broke up the rime (/tepsilons/) as to produce errors that retained the rime (/repsilonf/). Thus, a rime effect was obtained in a task that highlighted the phonological similarity between items sharing their rimes, but this effect disappeared in tasks without repetition of rime units. We conclude that children's sensitivity to rimes depends on similarity relations and might not reflect a fixed perceived structure of spoken syllables.

When does word meaning affect immediate serial recall in semantic dementia?

Patients with semantic dementia can show superior immediate recall of words that they still understand relatively well, as compared with more semantically degraded words, suggesting that conceptual knowledge makes a major contribution to phonological short-term memory. However, a number of studies have failed to show such a recall difference, challenging this view. We examined the effect of several methodological factors on the recall of known and degraded words in 4 patients with semantic dementia, in order to investigate possible reasons for this discrepancy. In general, our patients did exhibit poorer recall of the degraded words and made more phonological errors on these items. In addition, set size affected the magnitude of the recall advantage for known words. This finding suggests that semantic degradation influenced the rate of learning in the immediate recall task when the same items were presented repeatedly. The methods used to select known and degraded items also impacted on the recall difference. List length, however, did not affect the advantage for known words. The coherence of items in phonological short-term memory was affected by their semantic status, but not by the length of the material to be retained. The implications of these findings for the role of semantic and phonological representations in verbal short-term memory are discussed.

Unlimited capacity and processibility of sequence information: prerequisites for a system of biological chains

Both genetic chains in a cell and phonological chains in a human phonological working memory simultaneously store and process sequence information. Unlimited capacity and processibility of sequence information are two prerequisites for such a system of biological chains. It is demonstrated that information chains (I-chains) and conformation chains (C-chains) satisfy these two prerequisites. Namely, in both kinds of chains constant efficiency and precision of intra- and inter-sequence interactions are guaranteed irrespective of the chain length. Nucleic acids and proteins are I-chains and C-chains of genetic chains, respectively. A 'molecular' model of a phonological chain is formulated based on the properties of phonological working memory. It is proposed that prose and verse are I-chains and C-chains of phonological chains, respectively. The correspondence between a system of genetic chains and a system of phonological chains is explored in detail. A critical difference between systems of biological chains and artificial information-processing systems is attributed to the existence of C-chains.

Influence of onset density on spoken-word recognition

Previous research has suggested that the initial portion of a word activates similar sounding words that compete for recognition. Other research has shown that the number of similar sounding words that are activated influences the speed and accuracy of recognition. Words with few neighbors are processed more quickly and accurately than words with many neighbors. The influences of the number of lexical competitors in the initial part of the word were examined in a shadowing and a lexical-decision task. Target words with few neighbors that share the initial phoneme were responded to more quickly than target words with many neighbors that share the initial phoneme. The implications of onset-density effects for models of spoken-word recognition are discussed.

The development of phonological awareness: effects of spoken language experience and orthography

Phonological awareness, the ability to analyze spoken language into small sound units, has been shown to be affected by the individual's early orthographic experience (alphabetic vs. non-alphabetic). Past studies, however, have not differentiated the effect of script alphabeticity from that of spoken language experience, which covaries strongly with the phonological properties of the language. The present study compares younger, pre-reading to older, literate children from different linguistic backgrounds on their phonological awareness. Hong Kong and Guangzhou subjects both spoke Cantonese. The latter subjects had early experience with Pinyin (alphabetic) in addition to their logographic Chinese reading; the former read only logographic Chinese. New Zealand subjects spoke English and read the Roman alphabet. Results showed that: (1) the Hong Kong and Guangzhou pre-readers performed very similarly at all levels of phonological awareness; (2) the New Zealand pre-readers outperformed their Hong Kong and Guangzhou counterparts on onset, rime, and coda analyses; (3) the Guangzhou reading children outperformed their Hong Kong counterparts on onset and coda analyses. Whereas finding (3) reflects an effect of alphabeticity in the first learned script, finding (2) in combination with finding (1) indicates an effect of early spoken language experience independent of orthography. The fact that orthographic and spoken language experience both impact on the development of phonological skills implies a mediating function of phonological awareness in integrating sound information derived from reading and perceiving speech.

Does the medial temporal lobe bind phonological memories?

The medial temporal lobes play a central role in the consolidation of new memories. Medial temporal lesions impair episodic learning in amnesia, and disrupt vocabulary acquisition. To investigate the role of consolidation processes in phonological memory and to understand where and how, in amnesia, these processes begin to fail, we reexamined phonological memory in the amnesic patient HM. While HM's word span performance was normal, his supraspan recall was shown to be markedly impaired, with his recall characterized by a distinctive pattern of phonological errors, where he recombined phonemes from the original list to form new response words. These were similar to errors observed earlier for patients with specifically semantic deficits. Amnesic Korsakoff's patients showed a similar, though much less marked, pattern. We interpret the data in terms of a model of lexical representation where temporal lobe damage disrupts the processes that normally bind semantic and phonological representations.

The role of phonology in a letter detection task

In two experiments, we investigated whether onsets and rimes have a role in the processing of written English. In both experiments, participants detected letter targets (e.g., t) in nonwords like vult faster than in nonwords like vust. This finding is consistent with Selkirk's (1982) view that sonorants (e.g., the /l/ of vult) cohere with preceding short vowels and are part of the vowel nucleus. In contrast, the /t/ of vust is part of the syllable's coda st and so is harder to isolate. Experiment 2 demonstrated that the time required for one to detect single-member codas following vowel digraphs (e.g., the t in veet) was similar to the time to detect the same target letter following a postvocalic sonorant (e.g., the t in vult). No evidence was found for onsets. The results provide support for a phonological organization among letters of printed rimes.

Universal and Language-Specific Aspects of Word-Memory Processes: Japanese, Chinese, and English

The universal and language-specific features of word-memory processes were investigated. In Exp. 1, word lists in Japanese Kanji, Chinese, and English and two types of nonsense words (CV–CV and CVC–CVC) were presented auditorily or visually to native speakers of those languages for immediate recall, with or without suppression of the phonological loop by secondary digit memory tasks. English words were also presented to Japanese subjects. We found that phonological loop suppression in all the languages was associated with significant reduction in recall in every condition. When recalling meaningful words, English and Chinese subjects had superior recall with auditory presentation; however, Japanese subjects showed no significant differences between the two modalities and showed higher recall with visual presentation when English words were presented. When recalling nonsense words, all groups of subjects showed either higher recall with visual presentation or no differences between the modalities. Moreover, as the differences between the syllable structures of the subjects' native languages and the stimuli to be remembered increased, they were likely to rely on visual memory. In Exp. 2, lists of Kanji and Kana words were presented in the two modalities only to Japanese speakers. Auditory presentation was superior to visual presentation only for Kana words.

Vocabulary acquisition and verbal short-term memory: computational and neural bases

In this paper, we explore the hypothesis that human vocabulary acquisition processes and verbal short-term memory abilities utilize a common cognitive and neural system. We begin by reviewing behavioral evidence for a shared set of processes. Next, we examine what the computational bases of such a shared system might be and how vocabulary acquisition and verbal short-term memory might be related in mechanistic terms. We examine existing computational models of vocabulary acquisition and of verbal short-term memory, concluding that they fail to adequately relate these two domains. We then propose an alternative model which accounts not only for the relationship between word learning and verbal short-term memory, but also for a wide range of phenomena in verbal short-term memory. Furthermore, this new account provides a clear statement of the relationship between the proposed system and mechanisms of language processing more generally. We then consider possible neural substrates for this cognitive system. We begin by reviewing what is known of the neural substrates of speech processing and outline a conceptual framework within which a variety of seemingly contradictory neurophysiological and neuropsychological findings can be accommodated. The linkage of the shared system for vocabulary acquisition and verbal short-term memory to neural areas specifically involved in speech processing lends further support to our functional-level identification of the mechanisms of vocabulary acquisition and verbal short-term memory with those of language processing. The present work thus relates vocabulary acquisition and verbal short-term memory to each other and to speech processing, at a cognitive, computational, and neural level.

In defense of an onset-rime syllable structure for English

Many linguists and psycholinguists have suggested that English syllables have an onset-rime structure. Pierrehumbert and Nair (1995) have recently argued against this view and in favor of the idea that syllables have a moraic structure. We show that the results of word game experiments reported by Pierrehumbert and Nair are consistent with the onset-rime theory and that there are problems with their idea of output templates. Although people may learn about the phonological structure of a word game's output when they have a chance to do so, they tend to divide syllables at the boundary between the onset and the rime even when they do not have the opportunity to memorize a model. Moreover, the results of our recent statistical study of the distributions of phonemes in English syllables suggest that the rime is a domain for particularly close dependencies among phonemes. We conclude that Pierrehumbert and Nair's rejection of the onset-rime model was overly hasty and was based on a limited set of data. When a broad range of data is considered, the evidence supports the idea that English syllables have an onset-rime structure.

The sequential curing effect in speech production

How are the sounds of words represented in plans for speech production? In Experiment 1, subjects produced sequences of four CVCs as many times as possible in 8s. We varied the number of repetitions of the initial consonant, vowel, final consonant, CV, rhyme, and whole CVC each sequence required, and measured subjects' speaking rate. Subjects produced more CVCs when the final consonant or whole word was repeated, but were slowed when only initial sounds or CVs were repeated. Two other experiments replicate the location-based effects and extended them to bisyllabic words. We attribute the locational effects to competition between words that are formally similar, and specifically, to competition between discrepant phonemes in the two words to occupy a particular wordframe position. The fact that only discrepant initial, but not final sounds slow production suggests that phonemes are activated sequentially, from left to right.

Syllabification of bisyllabic nonwords: evidence from short-term memory errors

Do errors in short-term memory for spoken stimuli sometimes combine one syllable from one to-be-remembered item with one syllable from another to-be-remembered item? If so, can the errors shed light on how the stimuli are syllabified? We report three experiments in which college students tried to recall five-item lists containing two CVCVC (consonant-vowel-consonant-vowel-consonant) nonwords and three filler digits. When the second vowel of the nonword was stressed, recombination errors tended to blend the initial CV of one nonword with the final CVC of another, especially if the middle consonant was an obstruent. When the first vowel was stressed, the error pattern depended on the type of vowel. CV/CVC recombinations were more common for tense vowels than for lax vowels. In general, CV/CVC recombinations tended to be more frequent relative to CVC/VC recombinations when the middle consonant was an obstruent than when it was a sonorant. The findings are discussed in relation to linguistic theories of syllabification and the results of previous experiments using metalinguistic tasks.

The Impact of Semantic Memory Loss on Phonological Representations

Three patients with semantic dementia, involving progressive deterioration of semantic memory, performed immediate serial recall of short sequences of familiar words. On the basis of their performance in other tasks of word comprehension and production, the stimuli were selected individually for each patient as either known or unknown words. All patients showed a marked advantage in recall of known as compared to familiar but now unknown words. Errors consisted primarily of incorrect combinations of correct phoneme sequences in the stimulus string, with a large number of errors preserving onsethime syllable structure (e.g., mint, rug reproduced as “rint, mug”). Discussion focuses on the implication of these errors for the structure of phonological representations, and in particular on a hypothesis that meaning plays a crucial role in binding the elements of phonological word forms.

Orthographic onsets and rimes as functional units of reading

Three experiments are described in which a partial identity priming procedure was used to investigate the hypothesis that orthographic onsets and rimes serve as units of visual word recognition. In Experiment 1, partial identity priming using word-final trigrams was observed only when the bigram corresponded to the orthographic rime unit. Nonrime primes were again ineffective primes. In Experiment 3, partial identity priming using word-initial bigrams was observed only when the bigram corresponded to the orthographic onset unit. Non-onset bigrams were ineffective primes. These differential priming outcomes cannot be explained by graphemic priming, prime frequency, or practice effects. They are consistent with the hypothesis that syllable onset and rime units serve as functional units of reading.