William D. Marslen-Wilson

Functional parallelism in spoken word-recognition

Abstract The process of spoken word-recognition breaks down into three basic functions, of access, selection and integration. Access concerns the mapping of the speech input onto the representations of lexical form, selection concerns the discrimination of the best-fitting match to this input, and integration covers the mapping of syntactic and semantic information at the lexical level onto higher levels of processing. This paper describes two versions of a “cohort”-based model of these processes, showing how it evolves from a partially interactive model, where access is strictly autonomous but selection is subject to top-down control, to a fully bottom-up model, where context plays no role in the processes of form-based access and selection. Context operates instead at the interface between higher-level representations and information generated on-line about the syntactic and semantic properties of members of the cohort. The new model retains intact the fundamental characteristics of a cohort-based word-recognition process. It embodies the concepts of multiple access and multiple assessment, allowing a maximally efficient recognition process, based on the principle of the contingency of perceptual choice.

Processing interactions and lexical access during word recognition in continuous speech

Abstract The interactions, during word-recognition in continuous speech, between the bottom-up analyses of the input and different forms of internally generated top-down constraint, were investigated using a shadowing task and a mispronunciation detection task (in the detection task the subject saw a text of the original passage as he listened to it). The listeners dependence on bottom-up analyses in the shadowing task, as measured by the number of fluent restorations of mispronounced words, was found to vary as a function of the syllable position of the mispronunciation within the word and of the contextual constraints on the word as a whole. In the detection task only syllable position effects were obtained. The results, discussed in conjunction with earlier research, were found to be inconsistent with either the logogen model of word-recognition or an autonomous search model. Instead, an active direct access model is proposed, in which top-down processing constraints interact directly with bottom-up information to produce the primary lexical interpretation of the acoustic-phonetic input.

The temporal structure of spoken language understanding

Abstract The word-by-word time-course of spoken language understanding was investigated in two experiments, focussing simultaneously on word-recognition (local) processes and on structural and interpretative (global) processes. Both experiments used three word-monitoring tasks, which varied the description under which the word-target was monitored for (phonetic, semantic, or both) and three different prose contexts (normal, semantically anomalous, and scrambled), as well as distributing word-targets across nine word-positions in the test-sentences. The presence or absence of a context sentence, varied across the two experiments, allowed an estimate of between-sentence effects on local and global processes. The combined results, presenting a detailed picture of the temporal structuring of these various processes, provided evidence for an on-line interactive language processing theory, in which lexical, structural (syntactic), and interpretative knowledge sources communicate and interact during processing in an optimally efficient and accurate manner.

Morphology and meaning in the English mental lexicon

The authors investigated the lexical entry for morphologically complex words in English. Six experiments, using a cross-modal repetition priming task, asked whether the lexical entry for derivationally suffixed and prefixed words is morphologically structured and how this relates to the semantic and phonological transparency of the surface relationship between stem and affix. There was clear evidence for morphological decomposition of semantically transparent forms. This was independent of phonological transparency, suggesting that morphemic representations are phonologically abstract. Semantically opaque forms, in contrast, behave like monomorphemic words. Overall, suffixed and prefixed derived words and their stems prime each other through shared morphemes in the lexical entry, except for pairs of suffixed forms, which show a cohort-based interference effect

Integrating Form and Meaning: A Distributed Model of Speech Perception.

We present a new distributed connectionist model of the perception of spoken words. The model employs a representation of speech that combines lexical information with abstract phonological information, with lexical access modelled as a direct mapping onto this single distributed representation. We first examine the integration of partial cues to phonological identity, showing that the model provides a sound basis for simulating phonetic and lexical decision data from Marslen-Wilson and Warren (1994). We then investigate the time course of lexical access, and argue that the process of competition between word candidates during lexical access can be interpreted in terms of interference between distributed lexical representations. The relation between our model and other models of spoken word recognition is discussed.

The time course of visual word recognition as revealed by linear regression analysis of ERP data

EEG correlates of a range of psycholinguistic word properties were used to investigate the time course of access to psycholinguistic information during visual word recognition. Neurophysiological responses recorded in a visual lexical decision task were submitted to linear regression analysis. First, 10 psycholinguistic features of each of 300 stimulus words were submitted to a principal component analysis, which yielded four orthogonal variables likely to reflect separable processes in visual word recognition: Word length, Letter n-gram frequency, Lexical frequency and Semantic coherence of a words morphological family. Since the lexical decision task required subjects to distinguish between words and pseudowords, the binary variable Lexicality was also investigated using a factorial design. Word-pseudoword differences in the event-related potential first appeared at 160 ms after word onset. However, regression analysis of EEG data documented a much earlier effect of both Word length and Letter n-gram frequency around 90 ms. Lexical frequency showed its earliest effect slightly later, at 110 ms, and Semantic coherence significantly correlated with neurophysiological measures around 160 ms, simultaneously with the lexicality effect. Source estimates indicated parieto-temporo-occipital generators for the factors Length, Letter n-gram frequency and Word frequency, but widespread activation with foci in left anterior temporal lobe and inferior frontal cortex related to Semantic coherence. At later stages (>200 ms), all variables exhibited simultaneous EEG correlates. These results indicate that information about surface form and meaning of a lexical item is first accessed at different times in different brain systems and then processed simultaneously, thus supporting cascaded interactive processing models.

Sentence Perception as an Interactive Parallel Process

The restoration of disrupted words to their original form in a sentence shadowing task is dependent upon semantic and syntactic context variables, thus demonstrating an on-line interaction between the structural and the lexical and phonetic levels of sentence processing.

Morphological and semantic effects in visual word recognition : A time-course study

Some theories of visual word recognition postulate that there is a level of processing or representation at which morphemes are treated differently fromwhole words. Support for these theories has been derived frompriming experiments in which the recognition of a target word is facilitated by the prior presentation of a morphologically related prime (departure-DEPART). In English, such facilitation could be due to morphological relatedness, or to some combination of the orthographic and semantic relatedness characteristic of derivationally related words. We report two sets of visual priming experiments in which the morphological, semantic, and orthographic relationships between primes and targets are varied in three SOA conditions (43 ms, 72 ms, and 230 ms). Results showed that morphological structure plays a significant role in the early visual recognitionof English words that is independent of both semantic and orthographic relatedness. Findings are discussed in terms of current approaches to morphological processing.

Levels of perceptual representation and process in lexical access: words, phonemes, and features.

Three experiments and a simulation study investigate competing featural and phonemic views of the representation of the speech input in access to the mental lexicon. Auditory lexical decision and gating tasks show that the processing consequences of subcategorical mismatches (conflicts between phonetic cues to speech segment identity) depend on the lexical status of the conflicting cues, such that conflicts that only involve nonwords do not disrupt performance. A further study, using a phonetic-decision task with the same stimuli, found the same pattern. A simulation study shows that the interactive activation model TRACE, with top-down feedback to a prelexical phonemic level, does not model these effects successfully. The authors argue instead for a direct access featural model, based on a distributed computational substrate, where featural information is mapped directly onto lexical representations.

Accessing Spoken Words: The Importance of Word Onsets

Approaches to spoken word recognition differ in the importance they assign to word onsets during lexical access. This research contrasted the hypothesis that lexical access is strongly directional with the hypothesis that word onsets are less important than the overall goodness of fit between input and lexical form. A cross-modal priming technique was used to investigate the extent to which a rhyme prime (a prime that differs only in its first segment from the word that is semantically associated with the visual probe) is as effective a prime as the original word itself. Earlier research had shown that partial primes that matched from word onset were very effective cross-modal primes. The present results show that, irrespective of whether the rhyme prime was a real word or not, and irrespective of the amount of overlap between the rhyme prime and the original word, the rhymes are much less effective primes than the full word. In fact, no overall priming effect could be detected at all except under conditions in which the competitor environment was very sparse. This suggests that word onsets do have a special status in the lexical access of spoken words.