A motor theory of speech perception, initially proposed to account for results of early experiments with synthetic speech, is now extensively revised to accommodate recent findings, and to relate the assumptions of the theory to those that might be made about other perceptual modes. According to the revised theory, phonetic information is perceived in a biologically distinct system, a ‘module ’ specialized to detect the intended gestures of the speaker that are the basis for phonetic categories. Built into the structure of this module is the unique but lawful relationship between the gestures and the acoustic patterns in which they are variously overlapped. In consequence, the module causes perception of phonetic structure without translation from preliminary auditory impressions. Thus, it is comparable to such other modules as the one that enables an animal to localize sound. Peculiar to the phonetic module are the relation between perception and production it incorporates and the fact that it must compete with other modules for the same stimulus variations.

Data and models about recognition and recall of words and non words are unified using a real-time network processing theory. Lexical decision and word frequency effect data are analyzed in terms of theoretical concepts that have unified data about development of circular reactions, imitation of novel sounds, the matching of phonetic to articulatory requirements, serial and paired associate verbal learning, free recall, unitization, categorical perception, selective adaptation, auditory contrast, and word superiority effects. The theory, called adaptive resonance theory, arose from an analysis of how a language system self-organizes in real time in response to its complex input environment. Such an approach emphasizes the moment-by-moment dynamical interactions that control language development, learning, and stability. Properties of language performance emerge from an analysis of the system constraints that govern stable language learning. Concepts such as logogens, verification, automatic activation, interactive activation, limited-capacity processing, conscious attention, serial search, processing stages, speed-accuracy trade-off, situational frequency, familiarity, and encoding specificity are revised and developed using this analysis. Concepts such as adaptive resonance, resonant equilibration of short-term memory, bottom-up adaptive filtering, tQp-down adaptiveteml'late matching, competitive masking field, unitized list representation, temporal order information over item representations,

This study demonstrates that listeners use lexical knowledge in perceptual learning of speech sounds. Dutch listeners first made lexical decisions on Dutch words and nonwords. The final fricative of 20 critical words had been replaced by an ambiguous sound, between [f] and [s]. One group of listeners heard ambiguous [f]-final words (e.g., [WI WItlo?], from witlof, chicory) and unambiguous [s]-final words (e.g., naaldbos, pine forest). Another group heard the reverse (e.g., ambiguous [na:ldbo?], unambiguous witlof). Listeners who had heard [?] in [f]-final words were subsequently more likely to categorize ambiguous sounds on an [f]–[s] continuum as [f] than those who heard [?] in [s]-final words. Control conditions ruled out alternative explanations based on selective adaptation and contrast. Lexical information can thus be used to train categorization of speech. This use of lexical information differs from the on-line lexical feedback embodied in interactive models of speech perception. In contrast to online feedback, lexical feedback for learning is of benefit to spoken word recognition (e.g., in

Speech perception is an ecologically important example of the highly context-dependent nature of perception; adjacent speech, and even nonspeech, sounds influence how listeners categorize speech. Some theories emphasize linguistic or articulation-based processes in speech-elicited context effects and peripheral (cochlear) auditory perceptual interactions in non-speech-elicited context effects. The present studies challenge this division. Results of three experiments indicate that acoustic histories composed of sine-wave tones drawn from spectral distributions with different mean frequencies robustly affect speech categorization. These context effects were observed even when the acoustic context temporally adjacent to the speech stimulus was held constant and when more than a second of silence or multiple intervening sounds separated the nonlinguistic acoustic context and speech targets. These experiments indicate that speech categorization is sensitive to statistical distributions of spectral information, even if the distributions are composed of nonlinguistic elements. Acoustic context need be neither linguistic nor local to influence speech perception.

Previous studies have failed to demonstrate lexically induced delays in phoneme recognition, casting doubt on interactive models of speech perception. We present TRACE simulations that explain these failures: previously tested conditions failed to produce lexically induced delay effects because the input was too unambiguous and the control condition was conflated with lexical status and neighborhood structure. Since between-layer connections are solely excitatory, between-layer delay effects can emerge only indirectly through facilitation of within-layer competition. If the lexically consistent phoneme partially matches the input acoustics, it will become partially active. Additional support from lexical feedback will extend the duration of competition between the acoustically present phoneme and the lexically consistent phoneme, thus delaying detection. This prediction holds across a range of relevant parameter values. Two behavioral experiments tested and confirmed this prediction. These results answer one of the challenges to the interactive view of speech perception.

One of the central findings of speech perception is that identical acoustic signals can be perceived as different speech sounds depending on adjacent speech context. Although these phonetic context effects are ubiquitous in speech perception, their neural mechanisms remain largely unknown. The present work presents a review of recent data suggesting that spectral content of speech mediates phonetic contex effects and argues that these effects are likely to be governed by general auditory processes. A descriptive framework known as spectral contrast is presented as a means of interpreting these findings. Finally, and most centrally, four behavioral exavioral2 that begin to delineate the level of the auditory system at which interactions among stimulus components occur are described. Two of theseexe2II-5P2 investigate the influence of diotic versus dichotic presentation upon two phoneticcontex effects. Results indicate thatcontex effects remain even whencontex is presented to the ear contralateral to that of the target syllable. The other two exC4)CW2EexC4) the time course of phoneticcontex effects by manipulating the silent interval between contex and target syllables. These studies reveal that phonetic context effects persist for hundreds of milliseconds. Results are interpreted in terms of auditory mechanism with particular attention to the putative link between auditory enhancement and phonetic context effects.

Psycholinguistics refers to the empirical study of the human language processing system, typically using behavioral experiments. This chapter considers attempts to capture psycholinguistic data using connectionist models (Christiansen and Chater, 2001). We primarily focus on relatively ‘early ’ aspects of speech processing--speech segmentation

This paper is concerned with the influence of a preceding fricative on the production and perception of a stop consonant. In a well-known series of experiments (Mann & Repp, 1981; Repp & Mann, 1981, 1982), Mann and Repp showed that, when preceded by a fricative, an ambiguous stop acoustically halfway between /W/ and /N/ is identified differently depending on the place of articulation of the fricative. Specifically, listeners tend to identify stops more frequently as velars following /V/ than following /6/. This effect was shown to occur regardless of the presence/absence of a syllable boundary between the two consonants. It also appeared to decrease gradually in magnitude as a silence of increasing duration was inserted after the fricative, although it was still significant with silent gaps as long as 375 ms. As the listeners' responses were affected by both the specific acoustic structure of the fricative and its perceived category, it was suggested that the perceptual mechanism responsible for this effect was partly continuous and partly categorical, i.e. operated both before and after phonetic categorisation.

this paper. We are also grateful to Vincent Doyle for running a pilot version of Experiment 3 and developing the five new stimulus items used in Experiment 3. Sarah Hawkins provided invaluable advice on methods of assessing our materials in terms of casualness, and we also thank the phoneticians involved in generating the casualness ratings