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 feedforward. 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 lexicalaccess), and the theory opens new ways of approaching the cerebral organization of speech production by way of high-temporal-resolution imaging. (shrink)
According to embodied theories of language (ETLs), word meaning relies on sensorimotor brain areas, generally dedicated to acting and perceiving in the real world. More specifically, words denoting actions are postulated to make use of neural motor areas, while words denoting visual properties draw on the resources of visual brain areas. Therefore, there is a direct correspondence between word meaning and the experience a listener has had with a word's referent on the brain level. Behavioral and neuroimaging studies have provided (...) evidence in favor of ETLs; however, recent studies have also shown that sensorimotor information is recruited in a flexible manner during language comprehension (e.g., Raposo et al. ; Van Dam et al., ), leaving open the question as to what level of language processing sensorimotor activations contribute. In this study, we investigated the time course of modality-specific contributions (i.e., the contribution of action information) as to word processing by manipulating both (a) the linguistic and (b) the action context in which target words were presented. Our results demonstrate that processes reflecting sensorimotor information play a role early in word processing (i.e., within 200 ms of word presentation), but that they are sensitive to the linguistic context in which a word is presented. In other words, when sensorimotor information is activated, it is activated quickly; however, specific words do not reliably activate a consistent sensorimotor pattern. (shrink)
The present study investigated whether lexicalaccess is affected by a regular phonological variation in connected speech: voice assimilation in French. Two associative priming experiments were conducted to determine whether strongly assimilated, potentially ambiguous word forms activate the conceptual representation of the underlying word. Would the ambiguous word form [sud] (either assimilated soute 'hold' or soude 'soda') facilitate 'bagage' 'luggage', which is semantically related to soute but not to soude? In Experiment 1, words in either canonical or strongly (...) assimilated form were presented as primes. Both forms primed their related target to the same extent. Potential lexical ambiguity did not modulate priming effects. In Experiment 2, the primes such as assimilated soute pronounced [sud] used in Experiment 1 were replaced with primes such as soude canonically pronounced [sud]. No semantic priming effect was obtained with these primes. Therefore, the effect observed for assimilated forms in Experiment 1 cannot be due to overall phonological proximity between canonical and assimilated forms. We propose that listeners must recover the intended words behind the assimilated forms through the exploitation of the remaining traces of the underlying form, however subtle these traces may be. (shrink)
By examining single-word reading times (in full sentences read for meaning), we show that (1) function words are accessed faster than content words, independent of perceptual characteristics; (2) previous failures to show this involved problems of frequency range and task used; and (3) these differences in lexicalaccess are related to perceptual fluency. We relate these findings to issues in the literature on event-related potentials (ERPs) and neurolinguistics.
The following questions are addressed concerning how a theory of lexicalaccess can be realized in the brain: (1) Can a brainlike device function without inhibitory mechanisms? (2) Where in the brain can one expect to find processes underlying access to word semantics, syntactic word properties, phonological word forms, and their phonetic gestures? (3) If large neuron ensembles are the basis of such processes, how can one expect these populations to be connected? (4) In particular, how could (...) one-way, reciprocal, and numbered connections be realized? and, (5) How can a neuroscientific approach for multiple access to the same word in the course of the production of a sentence? Footnotes1 This commentary originally appeared in the Levelt et al. treatment in BBS 22(1) (pp. 52–54). (shrink)
The following questions are addressed concerning how a theory of lexicalaccess can be realized in the brain: (1) Can a brainlike device function without inhibitory mechanisms? (2) Where in the brain can one expect to find processes underlying access to word semantics, syntactic word properties, phonological word forms, and their phonetic gestures? (3) If large neuron ensembles are the basis of such processes, how can one expect these populations to be connected? (4) In particular, how could (...) one-way, reciprocal, and numbered connections be realized? and, (5) How can a neuroscientific approach for multiple access to the same word in the course of the production of a sentence? Footnotes1 This commentary will be responded to in the Continuing Commentary section of a forthcoming issue. (shrink)