Publications

Displaying 101 - 110 of 110
  • Ter Keurs, M., Brown, C. M., Hagoort, P., & Stegeman, D. F. (1999). Electrophysiological manifestations of open- and closed-class words in patients with Broca's aphasia with agrammatic comprehension: An event-related brain potential study. Brain, 122, 839-854. doi:10.1093/brain/122.5.839.

    Abstract

    This paper presents electrophysiological data on the on-line processing of open- and closed-class words in patients with Broca’s aphasia with agrammatic comprehension. Event-related brain potentials were recorded from the scalp when Broca patients and nonaphasic control subjects were visually presented with a story in which the words appeared one at a time on the screen. Separate waveforms were computed for open- and closed-class words. The non-aphasic control subjects showed clear differences between the processing of open- and closed-class words in an early (210-375 ms) and a late (400-700 ms) time-window.The early electrophysiological differences reflect the first manifestation of the availability of word-category information from the mental lexicon. The late differences presumably relate to post-lexical semantic and syntactic processing. In contrast to the control subjects, the Broca patients showed no early vocabulary class effect and only a limited late effect. The results suggest that an important factor in the agrammatic comprehension deficit of Broca’s aphasics is a delayed and/or incomplete availability of word-class information.
  • van Kuijk, D., & Boves, L. (1999). Acoustic characteristics of lexical stress in continuous telephone speech. Speech Communication, 27(2), 95-111. doi:10.1016/S0167-6393(98)00069-7.

    Abstract

    In this paper we investigate acoustic differences between vowels in syllables that do or do not carry lexical stress. In doing so, we concentrated on segmental acoustic phonetic features that are conventionally assumed to differ between stressed and unstressed syllables, viz. Duration, Energy and Spectral Tilt. The speech material in this study differs from the type of material used in previous research: instead of specially constructed sentences we used phonetically rich sentences from the Dutch POLYPHONE corpus. Most of the Duration, Energy and Spectral Tilt features that we used in the investigation show statistically significant differences for the population means of stressed and unstressed vowels. However, it also appears that the distributions overlap to such an extent that automatic detection of stressed and unstressed syllables yields correct classifications of 72.6% at best. It is argued that this result is due to the large variety in the ways in which the abstract linguistic feature `lexical stress' is realized in the acoustic speech signal. Our findings suggest that a lexical stress detector has little use for a single pass decoder in an automatic speech recognition (ASR) system, but could still play a useful role as an additional knowledge source in a multi-pass decoder.
  • Van Berkum, J. J. A., Brown, C. M., & Hagoort, P. (1999). Early referential context effects in sentence processing: Evidence from event-related brain potentials. Journal of Memory and Language, 41(2), 147-182. doi:10.1006/jmla.1999.2641.

    Abstract

    An event-related brain potentials experiment was carried out to examine the interplay of referential and structural factors during sentence processing in discourse. Subjects read (Dutch) sentences beginning like “David told the girl that … ” in short story contexts that had introduced either one or two referents for a critical singular noun phrase (“the girl”). The waveforms showed that within 280 ms after onset of the critical noun the reader had already determined whether the noun phrase had a unique referent in earlier discourse. Furthermore, this referential information was immediately used in parsing the rest of the sentence, which was briefly ambiguous between a complement clause (“ … that there would be some visitors”) and a relative clause (“ … that had been on the phone to hang up”). A consistent pattern of P600/SPS effects elicited by various subsequent disambiguations revealed that a two-referent discourse context had led the parser to initially pursue the relative-clause alternative to a larger extent than a one-referent context. Together, the results suggest that during the processing of sentences in discourse, structural and referential sources of information interact on a word-by-word basis.
  • Van Donselaar, W., Kuijpers, C. T., & Cutler, A. (1999). Facilitatory effects of vowel epenthesis on word processing in Dutch. Journal of Memory and Language, 41, 59-77. doi:10.1006/jmla.1999.2635.

    Abstract

    We report a series of experiments examining the effects on word processing of insertion of an optional epenthetic vowel in word-final consonant clusters in Dutch. Such epenthesis turns film, for instance, into film. In a word-reversal task listeners treated words with and without epenthesis alike, as monosyllables, suggesting that the variant forms both activate the same canonical representation, that of a monosyllabic word without epenthesis. In both lexical decision and word spotting, response times to recognize words were significantly faster when epenthesis was present than when the word was presented in its canonical form without epenthesis. It is argued that addition of the epenthetic vowel makes the liquid consonants constituting the first member of a cluster more perceptible; a final phoneme-detection experiment confirmed that this was the case. These findings show that a transformed variant of a word, although it contacts the lexicon via the representation of the canonical form, can be more easily perceptible than that canonical form.
  • Van Wijk, C., & Kempen, G. (1980). Functiewoorden: Een inventarisatie voor het Nederlands. ITL: Review of Applied Linguistics, 53-68.
  • Van Berkum, J. J. A., Hagoort, P., & Brown, C. M. (1999). Semantic integration in sentences and discourse: Evidence from the N400. Journal of Cognitive Neuroscience, 11(6), 657-671. doi:10.1162/089892999563724.

    Abstract

    In two ERP experiments we investigated how and when the language comprehension system relates an incoming word to semantic representations of an unfolding local sentence and a wider discourse. In experiment 1, subjects were presented with short stories. The last sentence of these stories occasionally contained a critical word that, although acceptable in the local sentence context, was semantically anomalous with respect to the wider discourse (e.g., "Jane told the brother that he was exceptionally slow" in a discourse context where he had in fact been very quick). Relative to coherent control words (e.g., "quick"), these discourse-dependent semantic anomalies elicited a large N400 effect that began at about 200-250 ms after word onset. In experiment 2, the same sentences were presented without their original story context. Although the words that had previously been anomalous in discourse still elicited a slightly larger average N400 than the coherent words, the resulting N400 effect was much reduced, showing that the large effect observed in stories was related to the wider discourse. In the same experiment, single sentences that contained a clear local semantic anomaly elicited a standard sentence-dependent N400 effect (e.g., Kutas & Hillyard, 1980). The N400 effects elicited in discourse and in single sentences had the same time course, overall morphology, and scalp distribution. We argue that these findings are most compatible with models of language processing in which there is no fundamental distinction between the integration of a word in its local (sentence-level) and its global (discourse-level) semantic context.
  • Van Berkum, J. J. A., Brown, C. M., & Hagoort, P. (1999). When does gender constrain parsing? Evidence from ERPs. Journal of Psycholinguistic Research, 28(5), 555-566. doi:10.1023/A:1023224628266.

    Abstract

    We review the implications of recent ERP evidence for when and how grammatical gender agreement constrains sentence parsing. In some theories of parsing, gender is assumed to immediately and categorically block gender-incongruent phrase structure alternatives from being pursued. In other theories, the parser initially ignores gender altogether. The ERP evidence we discuss suggests an intermediate position, in which grammatical gender does not immediately block gender-incongruent phrase structures from being considered, but is used to dispose of them shortly thereafter.
  • Van Turennout, M., Hagoort, P., & Brown, C. M. (1999). The time course of grammatical and phonological processing during speaking: evidence from event-related brain potentials. Journal of Psycholinguistic Research, 28(6), 649-676. doi:10.1023/A:1023221028150.

    Abstract

    Motor-related brain potentials were used to examine the time course of grammatical and phonological processes during noun phrase production in Dutch. In the experiments, participants named colored pictures using a no-determiner noun phrase. On half of the trials a syntactic-phonological classification task had to be performed before naming. Depending on the outcome of the classifications, a left or a right push-button response was given (go trials), or no push-button response was given (no-go trials). Lateralized readiness potentials (LRPs) were derived to test whether syntactic and phonological information affected the motor system at separate moments in time. The results showed that when syntactic information determined the response-hand decision, an LRP developed on no-go trials. However, no such effect was observed when phonological information determined response hand. On the basis of the data, it can be estimated that an additional period of at least 40 ms is needed to retrieve a word's initial phoneme once its lemma has been retrieved. These results provide evidence for the view that during speaking, grammatical processing precedes phonological processing in time.
  • De Weert, C., & Levelt, W. J. M. (1976). Comparison of normal and dichoptic colour mixing. Vision Research, 16, 59-70. doi:10.1016/0042-6989(76)90077-8.

    Abstract

    Dichoptic mixtures of equiluminous components of different wavelengths were matched with a binocularly presented "monocular" mixture of appropriate chosen amounts of the same colour components. Stimuli were chosen from the region of 490-630 nm. Although satisfactory colour matches could be obtained, dichoptic mixtures differed from normal mixtures to a considerable extent. Midspectral stimuli tended to be more dominant in the dichoptic mixtures than either short or long wavelength stimuli. An attempt was made to describe the relation between monocular and dichoptic mixtures with one function containing a wavelength variable and an eye dominance parameter.
  • De Weert, C., & Levelt, W. J. M. (1976). Dichoptic brightness combinations for unequally coloured lights. Vision Research, 16, 1077-1086.

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