Speech Production

Infants (from Latin infans, speechless) are human beings who cannot speak. It took most of us the whole first year of our lives to overcome this infancy and to produce our first few meaningful words, but we were not idle as infants. We worked, rather independently, on two basic ingredients of word production. On the one hand, we established our primary notions of agency, interactancy, the temporal and causal structures of events, object permanence and location. This provided us with a matrix for the creation of our first lexical concepts, concepts flagged by way of a verbal label. Initially, these word labels were exclusively auditory patterns, picked up from the environment. On the other hand, we created a repertoire of babbles, a set of syllabic articulatory gestures. These motor patterns normally spring up around the seventh month. The child carefully attends to their acoustic manifestations, leading to elaborate exercises in the repetition and concatenation of these syllabic patterns. In addition, these audiomotor patterns start resonating with real speech input, becoming more and more tuned to the mother tongue (De Boysson-Bardies & Vihman 1991; Elbers 1982). These exercises provided us with a protosyllabary, a core repository of speech motor patterns, which were, however, completely meaningless.

In this article the author proposes an episodic theory of spoken word representation, perception, and production. By most theories, idiosyncratic aspects of speech (voice details, ambient noise, etc.) are considered noise and are filtered in perception. However, episodic theories suggest that perceptual details are stored in memory and are integral to later perception. In this research the author tested an episodic model (MINERVA 2; D. L. Hintzman, 1986) against speech production data from a word-shadowing task. The model predicted the shadowing-response-time patterns, and it correctly predicted a tendency for shadowers to spontaneously imitate the acoustic patterns of words and nonwords. It also correctly predicted imitation strength as a function of ' 'abstract'' stimulus properties, such as word frequency. Taken together, the data and theory suggest that detailed episodes constitute the basic substrate of the mental lexicon.

This positron emission tomography study used a correlational design to investigate neural activity during speech perception in six normal subjects and two aphasic patients. The normal subjects listened either to speech or to signal-correlated noise equivalents; the latter were nonspeech stimuli, similar to speech in complexity but not perceived as speechlike. Regions common to the auditory processing of both types of stimuli were dissociated from those specific to spoken words. Increasing rates of presentation of both speech and nonspeech correlated with cerebral activity in bilateral transverse gyri and adjacent superior temporal cortex. Correlations specific to speech stimuli were located more anteriorly in both superior temporal sulci. The only asymmetry in normal subjects was a left lateralized response to speech in the posterior superior temporal sulcus, corresponding closely to structural asymmetry on the subjects' magnetic resonance images. Two patients, who had left temporal infarction but performed well on single word comprehension tasks, were also scanned while listening to speech. These cases showed right superior temporal activity correlating with increasing rates of hearing speech, but no significant left temporal activation. These findings together suggest that the dorsolateral temporal cortex of both hemispheres can be involved in prelexical processing of speech.

Magnetic resonance imaging was used to quantify the vocal tract morphology of 129 normal humans, aged 2-25 years. Morphometric data, including midsagittal vocal tract length, shape, and proportions, were collected using computer graphic techniques. There was a significant positive correlation between vocal tract length and body size ͑either height or weight͒. The data also reveal clear differences in male and female vocal tract morphology, including changes in overall vocal tract length and the relative proportions of the oral and pharyngeal cavity. These sex differences are not evident in children, but arise at puberty, suggesting that they are part of the vocal remodeling process that occurs during puberty in males. These findings have implications for speech recognition, speech forensics, and the evolution of the human speech production system, and provide a normative standard for future studies of human vocal tract morphology and development.

Gestures that spontaneously accompany speech convey information coordinated with the concurrent speech. There has been considerable theoretical disagreement about the process by which this informational coordination is achieved. Some theories predict that the information encoded in gesture is not influenced by how information is verbally expressed. However, others predict that gestures encode only what is encoded in speech. This paper investigates this issue by comparing informational coordination between speech and gesture across different languages. Narratives in Turkish, Japanese, and English were elicited using an animated cartoon as the stimulus. It was found that gestures used to express the same motion events were influenced simultaneously by (1) how features of motion events were expressed in each language, and (2) spatial information in the stimulus that was never verbalized. From this, it is concluded that gestures are generated from spatio-motoric processes that interact on-line with the speech production process. Through the interaction, spatio-motoric information to be expressed is packaged into chunks that are verbalizable within a processing unit for speech formulation. In addition, we propose a model of speech and gesture production as one of a class of frameworks that are compatible with the data.

Priming or nonconscious activation of social knowledge structures has produced a plethora of rather amazing findings over the past 25 years: priming a single social concept such as aggressive can have multiple effects across a wide array of psychological systems, such as perception, motivation, behavior, and evaluation. But we may have reached childhood's end, so to speak, and need now to move on to research questions such as how these multiple effects of single primes occur (the generation problem); next, how these multiple simultaneous priming influences in the environment get distilled into nonconscious social action that has to happen serially, in real time (the reduction problem). It is suggested that models of complex conceptual structures (Lakoff & Johnson, 1980), language use in real-life conversational settings (Clark, 1996), and speech production (Dell, 1986) might hold the key for solving these two important 'second-generation' research problems.

The evolution of speech can be studied independently of the evolution of language, with the advantage that most aspects of speech acoustics, physiology and neural control are shared with animals, and thus open to empirical investigation. At least two changes were necessary prerequisites for modern human speech abilities: (1) modification of vocal tract morphology, and (2) development of vocal imitative ability. Despite an extensive literature, attempts to pinpoint the timing of these changes using fossil data have proven inconclusive. However, recent comparative data from nonhuman primates have shed light on the ancestral use of formants (a crucial cue in human speech) to identify individuals and gauge body size. Second, comparative analysis of the diverse vertebrates that have evolved vocal imitation (humans, cetaceans, seals and birds) provides several distinct, testable hypotheses about the adaptive function of vocal mimicry. These developments suggest that, for understanding the evolution of speech, comparative analysis of living species provides a viable alternative to fossil data. However, the neural basis for vocal mimicry and for mimesis in general remains unknown. tel: ϩ1 617 496 6575 fax: ϩ1 617 496 8355 References 1 Ralls, K. et al. (1985) Vocalizations and vocal mimicry in captive harbor seals: 6 Corballis, M. (1992) On the evolution of language and generativity. Cognition 44, 197-226 7 Jackendoff, R. (1999) Possible stages in the evolution of the language capacity. Trends Cognit. Sci. 3, 272-279 8 Ghazanfar, A.A. and Hauser, M.D. (1999) The neuroethology of primate vocal communication: substrates for the evolution of speech.

Lexical access in object naming involves the activation of a set oflexical candidates, the selection of the appropriate (or target) item, and the phonological encoding of that item. Two views of lexical access in naming are compared. From one view, the 2-stage theory, phonological activation follows selection of the target item and is restricted to that item. From the other view, which is most explicit in activation-spreading theories, all activated lexical candidates are phonologically activated to some extent. A series of experiments is reported in which subjects performed acoustic lexical decision during object naming at different stimulus-onset asynchronies. The experiments show semantic activation of lexical candidates and phonological activation of the target item, but no phonological activation of other semantically activated items. This supports the 2-stage view. Moreover, a mathematical model embodying the 2-stage view is fully compatible with the lexical decision data obtained at different stimulus-onset asynchronies.

The study reported in this article aimed to investigate the way working memory capacity (WMC) interacts with careful online planning—a task-based implementation variable—to affect second language (L2) speech production. This issue is important to teachers, because it delves into one of the possible task-based implementation variables and thus could assist them in making empirically informed decisions in the classroom. It also bears significance for second language acquisition (SLA) researchers, in that it could help them test claims regarding the nature of interlanguages as well as the validity of speech production models that are essential in discussing the role and psycholinguistic functioning of planning in L2 performance and L2 acquisition (Ellis, 2005, 2009).

After describing the importance of visual information in speech perception and sketching the history of visual speech synthesis, we consider a number of theories of coarticulation in human speech. An implementation of Lo .. fqvist's (1990) gestural theory of speech production is described for visual speech synthesis along with a description of the graphically controlled development system. We conclude with some plans for future work.

The perception of action is associated with increased activity in motor regions, implicating such regions in the recognition, understanding and imitation of actions. We examined the possibility that perception of speech, both auditory and visual, would also result in changes in the excitability of the motor system underlying speech production. Transcranial magnetic stimulation was applied to the face area of primary motor cortex to elicit motor-evoked potentials in the lip muscles. The size of the motor-evoked potentials was compared under the following conditions: listening to speech, listening to non-verbal sounds, viewing speech-related lip movements, and viewing eye and brow movements. Compared to control conditions, listening to and viewing speech enhanced the size of the motor-evoked potential. This effect was only seen in response to stimulation of the left hemisphere; stimulation of the right hemisphere produced no changes in motor-evoked potentials in any of the conditions. In a control experiment, the size of the motor-evoked potentials elicited in the muscles of the right hand did not differ among conditions, suggesting that speech-related changes in excitability are specific to the lip muscles. These results provide evidence that both auditory and visual speech perception facilitate the excitability of the motor system involved in speech production.

Over time, both the functional and anatomical boundaries of 'Wernicke's area' have become so broad as to be meaningless. We have re-analysed four functional neuroimaging (PET) studies, three previously published and one unpublished, to identify anatomically separable, functional subsystems in the left superior temporal cortex posterior to primary auditory cortex. From the results we identified a posterior stream of auditory processing. One part, directed along the supratemporal cortical plane, responded to both non-speech and speech sounds, including the sound of the speaker's own voice. Activity in its most posterior and medial part, at the junction with the inferior parietal lobe, was linked to speech production Abbreviations: HG ϭ Heschl's gyrus; PT ϭ planum temporale; rCBF ϭ regional cerebral blood flow; SCN ϭ signal correlated noise; SPM99 ϭ statistical parametric mapping software (1999 version); STG ϭ superior temporal gyrus; STS ϭ superior temporal sulcus

In a series of picture-word interference experiments, Catalan-Spanish bilinguals named pictures in Catalan with distractor words printed either in Catalan (same-language pairs) or in Spanish (differentlanguage pairs). Naming was facilitated when the distractor was the name of the picture in both same-[e.g., taula-taula (table in Catalan)] and different-language pairs [e.g., taula-mesa (table in Spanish)]. We also found that the facilitation effect was larger for same-language pairs and that semantically related distractors in the same-vs different-language conditions were similarly interfering. These results are interpreted within a lexical model that assumes that only words of the target language are considered for lexical selection and can, therefore, compete for selection. Converging evidence from several experiments indicates that the facilitation asymmetry for same name distractors arises because same-language distractors can activate target phonemes via nonlexical, graphemephoneme conversion processes. Facilitation was obtained with phonologically related distractors for both same-and different-language conditions but not for their translations. The results suggest that nonlexical phonological processes contribute to the phonological facilitation effect.

This paper describes two electromagnetic midsagittal articulometer (EMMA) systems that were developed for transducing articulatory movements during speech production. Alternating magnetic fields are generated by transmitter coils that are mounted in an assembly that fits on the head of a speaker. The fields induce alternating voltages in a number of small transducer coils that are attached to articulators in the midline plane, inside and outside the vocal tract. The transducers are connected by fine lead wires to receiver electronics whose output voltages are processed to yield measures of transducer locations as a function of time. Measurement error can arise with this method, because as the articulators move and change shape, the transducers can undergo a varying amount of rotational misalignment with respect to the transmitter axes; both systems are designed to correct for transducer misalignment. For this purpose, one system uses two transmitters and biaxial transducers; the other uses three transmitters and single-axis transducers. The systems have been compared with one another in terms of their performance, human subjects compatibility, and ease of use. Both systems can produce useful midsagittal-plane data on articulator movement, and each one has a specific set of advantages and limitations. (Two commercially available systems are also described briefly for comparison purposes.) If appropriate experimental controls are used, the three-transmitter system is preferable for practical reasons. Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 216.165.127.12 On: Thu, 06 Aug 2015 22:04:53 FIG. 4. A schematic diagram of a biaxial transducer. The "tilt-detecting" winding is designated by T and the "distance-detecting" winding is designated by D. • indicates lines of magnetic flux; d is the distance from a transmitter. Ti, Tw, and Ro are orthogonal axes passing through the center of the transducer. 13 is the angle of transducer tilt. 3080

& Several behavioral and brain imaging studies have demonstrated a significant interaction between speech perception and speech production. In this study, auditory cortical responses to speech were examined during self-production and feedback alteration. Magnetic field recordings were obtained from both hemispheres in subjects who spoke while hearing controlled acoustic versions of their speech feedback via earphones. These responses were compared to recordings made while subjects listened to a tape playback of their production. The amplitude of tape playback was adjusted to match the amplitude of self-produced speech. Recordings of evoked responses to both self-produced and tape-recorded speech were obtained free of movement-related artifacts. Responses to self-produced speech were weaker than were responses to tape-recorded speech. Responses to tones were also weaker during speech production, when compared with responses to tones recorded in the presence of speech from tape playback. However, responses evoked by gated noise stimuli did not differ for recordings made during selfproduced speech versus recordings made during taperecorded speech playback. These data suggest that during speech production, the auditory cortex (1) attenuates its sensitivity and (2) modulates its activity as a function of the expected acoustic feedback. &

The dominant view in the field of lexical access in speech production maintains that selection of a word becomes more difficult as the levels of activation of nontarget words increase-selection by competition. The authors tested this prediction in two sets of experiments. First, the authors show that participants are faster to name pictures of objects (e.g., "bed") in the context of semantically related verb distractors (e.g., sleep) compared with unrelated verb distractors (e.g., shoot). In the second set of experiments, the authors show that target naming latencies (e.g., "horse") are, if anything, faster for within-category semantically close distractor words (e.g., zebra) than for within-category semantically far distractor words (e.g., whale). In the context of previous research, these data ground a new empirical generalization: As distractor words become semantically closer to the target concepts-all else being equal-target naming is facilitated. This fact means that lexical selection does not involve competition, and consequently, that the semantic interference effect does not reflect a lexical level process. This conclusion has important implications for models of lexical access and interpretations of Stroop-like interference effects.

The age at which a child receives a cochlear implant seems to be one of the more important predictors of his or her speech and language outcomes. However, understanding the association between age at implantation and child outcomes is complex because a child's age, length of device use, and age at implantation are highly related. In this study, we investigate whether there is an added value to earlier implantation or whether advantages observed in child outcomes are primarily attributable to longer device use at any given age.

This study reports an activation likelihood estimation (ALE) meta-analysis of imaging studies of chronic developmental stuttering in adults. Two parallel meta-analyses were carried out: (1) stuttered production in the stutterers; (2) fluent production in the control subjects. The control subjects' data replicated previous analyses of single-word reading, identifying activation in primary motor cortex, premotor cortex, supplementary motor area, Rolandic operculum, lateral cerebellum, and auditory areas, among others. The stuttering subjects' analysis showed that similar brain areas are involved in stuttered speech as in fluent speech, but with some important differences. Motor areas were over-activated in stuttering, including primary motor cortex, supplementary motor area, cingulate motor area, and cerebellar vermis. Frontal operculum, Rolandic operculum, and anterior insula showed anomalous rightlaterality in stutterers. Auditory activations, due to hearing one's own speech, were essentially undetectable in stutterers. The phenomenon of efference copy is proposed as a unifying account of the pattern activation revealed within this ALE meta-analysis. This provides the basis for a stuttering system model that is testable and should help to advance the understanding and treatment of this disorder. Hum Brain Mapp 25: 105-117, 2005.

The DIVA model of speech production provides a computationally and neuroanatomically explicit account of the network of brain regions involved in speech acquisition and production. An overview of the model is provided along with descriptions of the computations performed in the different brain regions represented in the model. The latest version of the model, which contains a new right-lateralized feedback control map in ventral premotor cortex, will be described, and experimental results that motivated this new model component will be discussed. Application of the model to the study and treatment of communication disorders will also be briefly described.

Primary progressive aphasia is a clinical syndrome defined by progressive deficits isolated to speech and/or language, and can be classified into non-fluent, semantic and logopenic variants based on motor speech, linguistic and cognitive features. The connected speech of patients with primary progressive aphasia has often been dichotomized simply as 'fluent' or 'non-fluent', however fluency is a multidimensional construct that encompasses features such as speech rate, phrase length, articulatory agility and syntactic structure, which are not always impacted in parallel. In this study, our first objective was to improve the characterization of connected speech production in each variant of primary progressive aphasia, by quantifying speech output along a number of motor speech and linguistic dimensions simultaneously. Secondly, we aimed to determine the neuroanatomical correlates of changes along these different dimensions. We recorded, transcribed and analysed speech samples for 50 patients with primary progressive aphasia, along with neurodegenerative and normal control groups. Patients were scanned with magnetic resonance imaging, and voxel-based morphometry was used to identify regions where atrophy correlated significantly with motor speech and linguistic features. Speech samples in patients with the non-fluent variant were characterized by slow rate, distortions, syntactic errors and reduced complexity. In contrast, patients with the semantic variant exhibited normal rate and very few speech or syntactic errors, but showed increased proportions of closed class words, pronouns and verbs, and higher frequency nouns, reflecting lexical retrieval deficits. In patients with the logopenic variant, speech rate (a common proxy for fluency) was intermediate between the other two variants, but distortions and syntactic errors were less common than in the non-fluent variant, while lexical access was less impaired than in the semantic variant. Reduced speech rate was linked with atrophy to a wide range of both anterior and posterior language regions, but specific deficits had more circumscribed anatomical correlates. Frontal regions were associated with motor speech and syntactic processes, anterior and inferior temporal regions with lexical retrieval, and posterior temporal regions with phonological errors and several other types of disruptions to fluency. These findings demonstrate that a multidimensional quantification of connected speech production is necessary to characterize the differences between the speech patterns of each primary progressive aphasic variant adequately, and to reveal associations between particular aspects of connected speech and specific components of the neural network for speech production.

In the present study, we tested the hypothesis that bilingualism may cause a linguistic disadvantage in lexical access even for bilinguals' first and dominant language. To this purpose, we conducted a picture naming experiment comparing the performance of monolinguals and highly-proficient, L1-dominant bilinguals. The results revealed that monolinguals name pictures faster than bilinguals, both when bilinguals perform picture naming in their first and dominant language and when they do so in their weaker second language. This is the first time it has been demonstrated that bilinguals show a naming disadvantage in their L1 in comparison to monolingual speakers.

Speakers with autism spectrum disorders (ASD) show difficulties in suprasegmental aspects of speech production, or prosody, those aspects of speech that accompany words and sentences and create what is commonly called “tone of voice.” However, little is known about the perception of prosody, or about the specific aspects of prosodic production that result in the perception of “oddness.” The present study examined the perception and production of a range of specific prosodic elements in an experimental protocol involving natural speech among speakers with ASD between 14 and 21 years of age, in comparison with a typical control group. Results revealed ceiling effects limiting interpretation of findings for some aspects of prosody. However, there were significant between-group differences in aspects of stress perception and production. The implications of these findings for understanding prosodic deficits is speakers with autism spectrum disorders, and for future research in this area, are discussed.

When synthetic fricative noises from a [∫]-[s] continuum are followed by [a] or [u] (with appropriate formant transitions), listeners perceive more instances of [s] in the context of [u] than in the context of [a]. Presumably, this reflects a perceptual adjustment for the coarticulatory effect of rounded vowels on preceding fricatives. In Experiment 1, we found that varying the duration of the fricative noise leaves the perceptual context effect unchanged, whereas insertion of a silent interval following the noise reduces the effect substantially. Experiment 2 suggested that it is temporal separation rather than the perception of an intervening stop consonant that is responsible for this reduction, in agreement with recent, analogous observations on anticipatory coarticulation. In Experiment 3, we showed that the vowel context effect disappears when the periodic stimulus portion is synthesized so as to contain no formant transitions. To dissociate the contribution of formant transitions from contextual effects due to vowel quality per se, Experiment 4 employed synthetic fricative noises followed by periodic portions excerpted from naturally produced [∫a], [sa], [∫u], and [su]. The results showed strong and largely independent effects of formant transitions and vowel quality on fricative perception. In addition, we found a strong speaker (male vs. female) normalization effect. All three influences on fricative perception were reduced by temporal separation of noise and periodic stimulus portions. Although no single hypothesis can explain all of our results, they are generally supportive of the view that some knowledge of the dynamics of speech production has a role in speech perception.

We investigated the brain systems engaged during propositional speech (PrSp) and two forms of nonpropositional speech (NPrSp): counting and reciting overlearned nursery rhymes. Bilateral cerebral and cerebellar regions were involved in the motor act of articulation, irrespective of the type of speech. Three additional, left-lateralized regions, adjacent to the Sylvian sulcus, were activated in common: the most posterior part of the supratemporal plane, the lateral part of the pars opercularis in the posterior inferior frontal gyrus and the anterior insula. Therefore, both NPrSp and PrSp were dependent on the same discrete subregions of the anatomically ill-de®ned areas of Wernicke and Broca. PrSp was also dependent on a predominantly left-lateralized neural system distributed between multi-modal and amodal regions in posterior inferior parietal, anterolateral and medial temporal and medial prefrontal cortex. The lateral prefrontal and paracingulate cortical activity observed in previous studies of cued word retrieval was not seen with either NPrSp or PrSp, demonstrating that normal brainlanguage representations cannot be inferred from explicit metalinguistic tasks. The evidence from this study indicates that normal communicative speech is dependent on a number of left hemisphere regions remote from the classic language areas of Wernicke and Broca. Destruction or disconnection of discrete left extrasylvian and perisylvian cortical regions, rather than the total extent of damage to perisylvian cortex, will account for the qualitative and quantitative differences in the impaired speech production observed in aphasic stroke patients.

Speakers employ acoustic cues (pitch accents) to indicate that a word is important, but may also use visual cues (beat gestures, head nods, eyebrow movements) for this purpose. Even though these acoustic and visual cues are related, the exact nature of this relationship is far from well understood. We investigate whether producing a visual beat leads to changes in how acoustic prominence is realized in speech, and whether it leads to changes in how prominence is perceived by observers. For Experiment I (''making beats'') we use an original experimental paradigm in which speakers are instructed to realize a target sentence with different distributions of acoustic and visual cues for prominence. Acoustic analyses reveal that the production of a visual beat indeed has an effect on the acoustic realization of the co-occurring speech, in particular on duration and the higher formants (F 2 and F 3 ), independent of the kind of visual beat and of the presence and position of pitch accents. In Experiment II (''hearing beats''), it is found that visual beats have a significant effect on the perceived prominence of the target words. When a speaker produces a beat gesture, an eyebrow movement or a head nod, the accompanying word is produced with relatively more spoken emphasis. In Experiment III (''seeing beats''), finally, it is found that when participants see a speaker realize a visual beat on a word, they perceive it as more prominent than when they do not see the beat gesture.

Ten fluent speakers and nine developmental stutterers speakers but was silent in stutterers. On the other hand, suppression of motor cortical 20-Hz rhythm, reflecting read isolated nouns aloud in a delayed reading paradigm. task-related neuronal processing, occurred bilaterally Cortical activation sequences were mapped with a wholein both groups. Moreover, the suppression was head magnetoencephalography system. The stutterers right-hemisphere dominant in stutterers, as opposed to were mostly fluent in this task. Although the overt left-hemisphere dominant in fluent speakers. Accordingly, performance was essentially identical in the two groups, the right frontal cortex of stutterers was highly active the cortical activation patterns showed clear differences, during speech production but did not generate both in the evoked responses, time-locked to word synchronous time-locked responses. The speech-related presentation and mouth movement onset, and in task-20-Hz suppression concentrated in the mouth area in related suppression of 20-Hz oscillations. Within the first fluent speakers, but was evident in both the hand and 400 ms after seeing the word, processing in fluent speakers mouth areas in stutterers. These findings may reflect advanced from the left inferior frontal cortex (articulatory imprecise functional connectivity within the right frontal programming) to the left lateral central sulcus and dorsal cortex and incomplete segregation between the adjacent premotor cortex (motor preparation). This sequence was hand and mouth motor representations in stutterers reversed in the stutterers, who showed an early left motor during speech production. A network including the left cortex activation followed by a delayed left inferior inferior frontal cortex and the right motor/premotor frontal signal. Stutterers thus appeared to initiate motor cortex, likely to be relevant in merging linguistic and programmes before preparation of the articulatory code. affective prosody with articulation during fluent speech, During speech production, the right motor/premotor thus appears to be partly dysfunctional in developmental stutterers. cortex generated consistent evoked activation in fluent

Word retrieval ability is commonly assessed with a semantic verbal fluency task, in which subjects must produce a list of exemplars of a category (e.g., animals). The order in which exemplars are produced is not random; rather, subjects tend to produce "clusters" of semantically related items (e.g., cow, pig, sheep) and occasionally "switch" to other clusters (e.g., lion, tiger, bear).

To what extent do bilinguals have a single, integrated representation of syntactic information? According to . Is syntax separate or shared between languages? Cross-linguistic syntactic priming in Spanish-English bilinguals. Psychological Science, 15, 409-414.], bilinguals represent syntactic information in terms of links between lexical representations and combinatorial nodes that specify syntactic structure, in a single cross-linguistic network. We describe predictions of this account and test them in two pairs of syntactic priming experiments with Dutch-English bilinguals. In Experiments 1 and 2, we tested priming in English (L2) production. Experiment 1 showed priming within English, and found that this priming was boosted by lexical repetition. Experiment 2 showed priming from Dutch to English, and found that this priming was boosted when prime and target used translation-equivalent verbs. However, this boost was weaker than the lexical boost in Experiment 1. In Experiments 3 and 4, we tested priming in Dutch (L1) production. Experiment 3 showed priming within Dutch, again boosted by lexical repetition. Experiment 4 showed priming from English to Dutch, but found no boost when prime and target were translation-equivalent verbs. We interpret these results in terms of an integrated model of lexical-syntactic representation.

Speakers plan the phonological content of their utterances prior to 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 (CQ) models have followed Lashley (1951) in assuming that inherently parallel neural representations underlie serial action, and this idea is increasingly supported by experimental evidence. In this paper we develop 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, 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 multi-syllabic 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 thalamus. The new model, called GODIVA (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.

To distinguish the neural systems of normal speech from those of stuttering, PET images of brain blood flow were probed (correlated voxel-wise) with per-trial speechbehaviour scores obtained during PET imaging. Two cohorts were studied: 10 right-handed men who stuttered and 10 right-handed, age-and sex-matched non-stuttering controls. Ninety PET blood flow images were obtained in each cohort (nine per subject as three trials of each of three conditions) from which r-value statistical parametric images (SPI{r}) were computed. Brain correlates of stutter rate and syllable rate showed striking differences in both laterality and sign (i.e. positive or negative correlations). Stutter-rate correlates, both positive and negative, were strongly lateralized to the right cerebral and left cerebellar hemispheres. Syllable correlates in both cohorts were bilateral, with a bias towards the left cerebral and right cerebellar hemispheres, in keeping with the left-cerebral dominance for language and motor skills typical of righthanded subjects. For both stutters and syllables, the brain regions that were correlated positively were those of speech production: the mouth representation in the Abbreviations: BA ϭ Brodmann area; SMA ϭ supplementary motor area; ILPrM ϭ inferior lateral premotor cortex; FEF ϭ frontal eye fields; M1 ϭ primary motor cortex; fMRI ϭ functional MRI; SPI{r} ϭ statistical parametric image of r-values

How are bilinguals able to switch from one language to another? The prevailing inhibition hypothesis takes larger reaction-time (RT) costs for switching to the first language (L1) than to the second language (L2) as evidence for suppression of the non-target language. Switch cost asymmetries can alternatively be explained by an L1-repeat-benefit, assuming selective absence of language competition in repeating L1. To test the latter hypothesis, RTs and event-related brain potentials (ERPs) were recorded when unbalanced Dutch-English bilinguals switched between overt picture naming in L1 and L2. Preparation time (short versus long cue-stimulus intervals) modulated the degree to which top-down inhibitory control biased language competition, as indexed by the N2 component of the ERP. RT switch costs were asymmetrical on short intervals and symmetrical on long intervals. Preparation interval effects were observed in all conditions except for L1 repeat trials. This pattern was present both for RT and N2 data, thereby supporting the L1-repeat-benefit hypothesis. These results suggest that inhibition is not necessary, but can modulate the efficiency of language switching.

Language can be viewed as a structuring of cognitive units that can be transmitted among individuals for the purpose of communicating information. Cognitive units stand in specific and systematic relationships with one another, and linguists are interested in the characterization of these units and the nature of these relationships. Both can be examined at various levels of granularity. It has long been observed that languages exhibit distinct patterning of units in syntax and in phonology. This distinction, a universal characteristic of language, is termed duality of patterning . Syntax refers to the structuring of words in sequence via hierarchical organization, where words are meaningful units belonging to an infinitely expandable set. But words also are composed of structured cognitive units. Phonology structures a small, closed set of recombinable, non-meaningful units that compose words (or signs, in the case of signed languages). It is precisely the use of a set of non-meaningful arbitrary discrete units that allows word creation to be productive. 1 In this chapter we outline a proposal that views the evolution of syntax and of phonology as arising from different sources and ultimately converging in a symbiotic relationship. Duality of patterning forms the intellectual basis for this proposal. Grasp and other manual gestures in early hominids are, as Arbib (Chapter 1, this volume) notes, well suited to provide a link from the iconic to the symbolic. Critically, the iconic aspects of manual gestures lend them a meaningful aspect that is critical to evolution of a system of symbolic units. However, we will argue that, given duality of patterning, phonological evolution crucially requires the emergence of effectively non-meaningful combinatorial units. We suggest that vocal tract action gestures are well suited to play a direct role in phonological evolution because, as argued by Studdert-Kennedy (2002a), they are Action to Language via the Mirror Neuron System, ed. Michael A. Arbib. Published by Cambridge University Press. © Cambridge University Press 2006. vocal-acoustic-auditory chain of communication. However, we are suggesting that the systems evolved in parallel complementary ways, and the existence of signed languages with syntactic structures comparable to spoken language indicates that a manual-optic-visual chain remains accessible for communication, given a suitably structured linguistic system, namely one having duality of patterning. 4 Except where they directly interact with one another, in the prosodic form of utterances. function as atoms or integral building blocks; further, it requires a "glue" that can bond these atomic units together into larger combinatorial structures or molecules. From an evolutionary perspective, we wish to consider the possibility that the basis for these (units and glue) was already largely present in the vocal tract and its control before the evolution of phonology, thus explaining how such a system might have readily taken on (or over) the job of distinguishing words from one another.

The four purposes of this investigation were to assess whether children acquire intelligible speech following prolonged cochlear-implant experience and examine their speech error patterns, to examine how age at implantation influences speech acquisition, to assess how speech production and speech perception skills relate, and to determine whether cochlear implant recipients who formerly used simultaneous communication (speech and manually coded English) begin to use speech without sign to communicate. Twenty-eight prelinguistically deafened children who use a Nucleus cochlear implant were assigned to one of three age groups, according to age at implantation: 2-5 yrs (N = 12), 5-8 yrs (N = 9), and 8-15 yrs (N = 7). All subjects had worn a cochlear implant for at least 24 mos, and an average of 36 mos. All subjects used simultaneous communication at the time of implantation. Subjects performed both imitative and structured spontaneous sampling speech tasks. The results permit the following conclusions: (a) children who have used a cochlear implant for at least 2 yrs acquire some intelligible speech; (b) children who receive a cochlear implant before the age of 5 yrs appear to show greater benefit in their speech production skills than children who are older, at least after a minimum of 2 yrs of use; (c) children who recognize more speech while wearing their cochlear implants are likely to speak more intelligibly; and, (d) signing does not disappear from a child's communication mode following implantation.

Errors in the repetition and serial recall of nonwords indicate that structural properties of the syllable are represented in short-term memory. We develop a connectionist model of short-term memory for such unfamiliar phonological sequences, based on insights from existing models of speech production and short-term memory. The results of simulations of experiments involving nonword recall and repetition are presented, and the mechanisms which produce the common error types are discussed. We also show how the proposed model can be extended to develop and make use of long-term representations of phonological forms, and how a global reduction in short-term memory capacity (such as is commonly observed in developmental dyslexia, and acquired disorders of output phonology) could differentially affect performance on tasks involving familiar and unfamiliar materials.

This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which if they grow large enough, can cause the motor system to "reset" and repeat the current syllable. This hypothesis is investigated using computer simulations of a "neurally impaired" version of the DIVA model, a neural network model of speech acquisition and production. The model's outputs are compared to published acoustic data from PWS' fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject's speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control.

A theory of speech monitoring, proposed by Levelt (1983), assumes that the quality of one's speech is checked by the speech comprehension system. This system inspects one's own overt speech but would also inspect an inner speech plan (''the inner loop''). We have elaborated and tested this theory by way of formalizing it as a computational model. This model includes a new proposal concerning the timing relation between planning the interruption and the repair: the proposal that these two processes are performed in parallel. We attempted to simulate empirical data about the distribution of error-to-cutoff and cutoff-to-repair intervals and the effect of speech rate on these intervals (these intervals are shorter with faster speech). The main questions were (1) Is an inner monitor that utilizes the speech perception system fast enough to simulate the timing data? (2) Can the model account for the effects of speech rate on these intervals? We conclude that including an inner loop through the speech comprehension system generates predictions that fit the empirical data. The effects of speed can be accounted for, given our proposal about the time course of planning interruption and repair. A novel prediction is that the error-tocutoff interval decreases with increasing position in the phrase.

In the past, the nature of the compositional units proposed for spoken language has largely diverged from the types of control units pursued in the domains of other skilled motor tasks. A classic source of evidence as to the units structuring speech has been patterns observed in speech errors -"slips of the tongue". The present study reports, for the Wrst time, on kinematic data from tongue and lip movements during speech errors elicited in the laboratory using a repetition task. Our data are consistent with the hypothesis that speech production results from the assembly of dynamically deWned action units -gestures -in a linguistically structured environment. The experimental results support both the presence of gestural units and the dynamical properties of these units and their coordination. This study of speech articulation shows that it is possible to develop a principled account of spoken language within a more general theory of action.

Traditionally, models of speech comprehension and production do not depend on concepts and processes from the phonological short-term memory (pSTM) literature. Likewise, in working memory research, pSTM is considered to be a language-independent system that facilitates language acquisition rather than speech processing per se. We discuss couplings between pSTM, speech perception and speech production, and we propose that pSTM arises from the cycling of information between two phonological buffers, one involved in speech perception and one in speech production. We discuss the specific role of these processes in speech processing, and argue that models of speech perception and production, and our understanding of their neural bases, will benefit from incorporating them.