The processing of free and bound gender-marked morphemes in speech production: evidence from Dutch

In many languages, the production of noun phrases requires the selection of gender-marked elements like determiners or inflectional suffixes. There is a recent debate as to whether the selection of freestanding gender-marked elements, such as determiners, follows the same processing mechanisms as the selection of bound gender-marked morphemes, such as adjective suffixes. Most of the evidence on which this debate is based relates to the gender-congruency effect in picture-word interference experiments. In the present article, the authors address this issue with a pure picture-naming task, extending previous work in German (H. Schriefers, J. D. Jescheniak, & A. Hantsch, 2005). The results of the present study on noun phrase production in Dutch show that both types of gender-marked morphemes are selected via the same basic processing mechanisms.     

A cross-sectional study of the acquisition of grammatical morphemes in child speech

Speech samples were taken from 21 children aged 16–40 months covering a wide range of mean utterance length. Presence or absence of 14 grammatical morphemes in linguistic and nonlinguistic obligatory contexts was scored. Order of acquisition of the morphemes was determined using two different criteria. The rank-orderings obtained correlated very highly with a previously determined order of acquisition for three children studied longitudinally. Age did not add to the predictiveness of mean length of utterance alone for grammatical development in terms of which morphemes were correctly used. The approximately invariant order of acquisition for the fourteen morphemes is discussed in terms of three possible determinants of this order. Frequency of use in parental speech showed no correlation with order of acquisition, but grammatical and semantic complexity both correlated highly with acquisition order.This research was supported in part by PHS grant HD-02908 from the National Institute of Child Health and Development.     

Different selection principles of freestanding and bound morphemes in language production

Freestanding and bound morphemes differ in many (psycho)linguistic aspects. Some theorists have claimed that the representation and retrieval of freestanding and bound morphemes in the course of language production are governed by similar processing mechanisms. Alternatively, it has been proposed that both types of morphemes may be selected for production in different ways. In this article, the authors first review the available experimental evidence related to this topic and then present new experimental data pointing to the notion that freestanding and bound morphemes are retrieved following distinct processing principles: freestanding morphemes are subject to competition, bound morphemes not.     

Variation in the pattern of omissions and substitutions of grammatical morphemes in the spontaneous speech of so-called agrammatic patients

We describe the patterns of omissions (and substitutions) of freestanding grammatical morphemes and the patterns of substitutions of bound grammatical morphemes in 20 so-called agrammatic patients. Extreme variation was observed in the patterns of omissions and substitutions of grammatical morphemes, both in terms of the distribution of errors for different grammatical morphemes as well as in terms of the distribution of omissions versus substitutions. Results are discussed in the context of current debates concerning the possibility of a theoretically motivated distinction between the clinical categories of agrammatism and paragrammatism and, more generally, concerning the theoretical usefulness of any clinical category. The conclusion is reached that the observed heterogeneity in the production of grammatical morphemes among putatively agrammatic patients renders the clinical category of agrammatism, and by extension all other clinical categories from the classical classification scheme (e.g., Broca's aphasia, Wernicke's aphasia, and so forth) to more recent classificatory attempts (e.g., surface dyslexia, deep dysgraphia, and so forth), theoretically useless.     

Levels of processing in speech production

When subjects repeated short alphabetic sequences at experimenter-controlled rates while retaining consonant trigrams, subsequent recall was unrelated to speech rate if single letters or a long sequence was repeated, but recall was inversely related to speech rate for sequences three or five letters in length. The latter effect was predicted by a model in which sequences were organized as single response units in a central phonetic processor but independently executed by means of mechanisms not requiring the services of the central processor. Quantitative predictions were generated from this model by estimating organization time for the sequences and assuming that the probability of forgetting would be equal to the organization time/execution time ratio. All obtained recall probabilities were as predicted for sequences three of five letters in length with both experimenter- and subject-controlled speech rates. Repetition of a nine-letter sequence from the end of the alphabet produced forgetting patterns clearly out of accord with any organization time/execution time ratio, but a similar sequence from the beginning of the alphabet produced evidence of being a marginal case with unstable organization.     

Articulatory duration in single-word speech production

Three different speech production paradigms assessed C. T. Kello, D. C. Plaut, and B. MacWhinney's (2000) claim that the characteristics of speech production flexibly vary between staged and cascaded modes depending on task demand. All experiments measured response latencies and durations of single words without and with a response deadline. Experiment 1 used a picture-word interference task; Experiment 2 blocked pictures either by semantic category or by word-initial overlap; and Experiment 3 used a Stroop paradigm. In all cases, systematic effects of semantic and form relatedness were obtained on latencies but not on response durations. These results support the assumption that articulation, as assessed by response duration, is never influenced by central cognitive processes once a response has been initiated.     

Effects of syllable frequency in speech production

In the speech production model proposed by [Levelt, W. J. M., Roelofs, A., Meyer, A. S. (1999). A theory of lexical access in speech production. Behavioral and Brain Sciences, 22, pp. 1-75.], syllables play a crucial role at the interface of phonological and phonetic encoding. At this interface, abstract phonological syllables are translated into phonetic syllables. It is assumed that this translation process is mediated by a so-called Mental Syllabary. Rather than constructing the motor programs for each syllable on-line, the mental syllabary is hypothesized to provide pre-compiled gestural scores for the articulators. In order to find evidence for such a repository, we investigated syllable-frequency effects: If the mental syllabary consists of retrievable representations corresponding to syllables, then the retrieval process should be sensitive to frequency differences. In a series of experiments using a symbol-position association learning task, we tested whether high-frequency syllables are retrieved and produced faster compared to low-frequency syllables. We found significant syllable frequency effects with monosyllabic pseudo-words and disyllabic pseudo-words in which the first syllable bore the frequency manipulation; no effect was found when the frequency manipulation was on the second syllable. The implications of these results for the theory of word form encoding at the interface of phonological and phonetic encoding; especially with respect to the access mechanisms to the mental syllabary in the speech production model by (Levelt et al.) are discussed.     

Network structure influences speech production

Network science provides a new way to look at old questions in cognitive science by examining the structure of a complex system, and how that structure might influence processing. In the context of psycholinguistics, clustering coefficient-a common measure in network science-refers to the extent to which phonological neighbors of a target word are also neighbors of each other. The influence of the clustering coefficient on spoken word production was examined in a corpus of speech errors and a picture-naming task. Speech errors tended to occur in words with many interconnected neighbors (i.e., higher clustering coefficient). Also, pictures representing words with many interconnected neighbors (i.e., high clustering coefficient) were named more slowly than pictures representing words with few interconnected neighbors (i.e., low clustering coefficient). These findings suggest that the structure of the lexicon influences the process of lexical access during spoken word production.     

Phonotactic probability influences speech production

Speakers are faster and more accurate at processing certain sound sequences within their language. Does this reflect the fact that these sequences are frequent or that they are phonetically less complex (e.g., easier to articulate)? It has been difficult to contrast these two factors given their high correlation in natural languages. In this study, participants were exposed to novel phonotactic constraints de-correlating complexity and frequency by subjecting the same phonological structure to varying degrees of probabilistic constraint. Participants' behavior was sensitive to variations in frequency, demonstrating that phonotactic probability influences speech production independent of phonetic complexity.     

Functional imaging during speech production

Physiological studies of speech production have demonstrated that even simple articulation involves a range of specialized motor and cognitive processes and the neural mechanisms responsible for speech reflect this complexity. Recently, a number of functional imaging techniques have contributed to our knowledge of the neuroanatomical and neurophysiological correlates of speech production. These new imaging approaches have the advantage of permitting study of large numbers of normal and disordered subjects but they bring with them a host of new methodological concerns. One of the challenges for understanding language production is the recording of articulation itself. The problems associated with measuring the vocal tract and measuring the neural activity during overt speech are reviewed. It is argued that advances in understanding fundamental questions such as what are the planning units of speech, what is the role of feedback during speech and what is the influence of learning, await the development of better methods for assessing task performance.     

Functional anatomy of speech perception and speech production: psycholinguistic implications

This paper presents evidence for a new model of the functional anatomy of speech/language (Hickok & Poeppel, 2000) which has, at its core, three central claims: (1) Neural systems supporting the perception of sublexical aspects of speech are essentially bilaterally organized in posterior superior temporal lobe regions; (2) neural systems supporting the production of phonemic aspects of speech comprise a network of predominately left hemisphere systems which includes not only frontal regions, but also superior temporal lobe regions; and (3) the neural systems supporting speech perception and production partially overlap in left superior temporal lobe. This model, which postulates nonidentical but partially overlapping systems involved in the perception and production of speech, explains why psycho- and neurolinguistic evidence is mixed regarding the question of whether input and output phonological systems involve a common network or distinct networks.     

A theory of lexical access in speech production

Preparing words in speech production is normally a fast and accurate process. We generate them two or three per second in fluent conversation; and overtly naming a clear picture of an object can easily be initiated within 600 msec after picture onset. The underlying process, however, is exceedingly complex. The theory reviewed in this target article analyzes this process as staged and feed-forward. After a first stage of conceptual preparation, word generation proceeds through lexical selection, morphological and phonological encoding, phonetic encoding, and articulation itself. In addition, the speaker exerts some degree of output control, by monitoring of self-produced internal and overt speech. The core of the theory, ranging from lexical selection to the initiation of phonetic encoding, is captured in a computational model, called WEAVER++. Both the theory and the computational model have been developed in interaction with reaction time experiments, particularly in picture naming or related word production paradigms, with the aim of accounting for the real-time processing in normal word production. A comprehensive review of theory, model, and experiments is presented. The model can handle some of the main observations in the domain of speech errors (the major empirical domain for most other theories of lexical access), and the theory opens new ways of approaching the cerebral organization of speech production by way of high-temporal-resolution imaging.     

The role of orthography in speech production revisited

The language production system of literate adults comprises an orthographic system (used during written language production) and a phonological system (used during spoken language production). Recent psycholinguistic research has investigated possible influences of the orthographic system on the phonological system. This research has produced contrastive results, with some studies showing effects of orthography in the course of normal speech production while others failing to show such effects. In this article, we review the available evidence and consider possible explanations for the discrepancy. We then report two form-preparation experiments which aimed at testing for the effects of orthography in spoken word-production. Our results provide clear evidence that the orthographic properties of the words do not influence their spoken production in picture naming. We discuss this finding in relation to psycholinguistic and neuropsychological investigations of the relationship between written and spoken word-production.     

Monitoring syllable boundaries during speech production

This study investigated the encoding of syllable boundary information during speech production in Dutch. Based on Levelt's model of phonological encoding, we hypothesized segments and syllable boundaries to be encoded in an incremental way. In a self-monitoring experiment, decisions about the syllable affiliation (first or second syllable) of a pre-specified consonant, which was the third phoneme in a word, were required (e.g., ka.No 'canoe' vs. kaN.sel 'pulpit'; capital letters indicate pivotal consonants, dots mark syllable boundaries). First syllable responses were faster than second syllable responses, indicating the incremental nature of segmental encoding and syllabification during speech production planning. The results of the experiment are discussed in the context of Levelt's model of phonological encoding.     

Neighbourhood effects on error rates in speech production

Models of speech production differ on whether phonological neighbourhoods should affect processing, and on whether effects should be facilitatory or inhibitory. Inhibitory effects of large neighbourhoods have been argued to underlie apparent anti-frequency effects, whereby high-frequency default features are more prone to mispronunciation errors than low-frequency nondefault features. Data from the original SLIPs experiments that found apparent anti-frequency effects are analysed for neighbourhood effects. Effects are facilitatory: errors are significantly less likely for words with large numbers of neighbours that share the characteristic that is being primed for error ("friends"). Words in the neighbourhood that do not share the target characteristic ("enemies") have little effect on error rates. Neighbourhood effects do not underlie the apparent anti-frequency effects. Implications for models of speech production are discussed.     

Dynamic action units slip in speech production errors

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 first 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 defined 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.     

Grammatical constraints on phonological encoding in speech production

To better understand the influence of grammatical encoding on the retrieval and encoding of phonological word-form information during speech production, we examine how grammatical class constraints influence the activation of phonological neighbors (words phonologically related to the target—e.g., MOON, TWO for target TUNE). Specifically, we compare how neighbors that share a target’s grammatical category (here, nouns) influence its planning and retrieval, assessed by picture naming latencies, and phonetic encoding, assessed by word productions in picture names, when grammatical constraints are strong (in sentence contexts) versus weak (bare naming). Within-category (noun) neighbors influenced planning time and phonetic encoding more strongly in sentence contexts. This suggests that grammatical encoding constrains phonological processing; the influence of phonological neighbors is grammatically dependent. Moreover, effects on planning times could not fully account for phonetic effects, suggesting that phonological interaction affects articulation after speech onset. These results support production theories integrating grammatical, phonological, and phonetic processes.