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W J Levelt

Publications and source records attributed to W J Levelt.

16 recordsLinked to original sources

Accessing words in speech production: stages, processes and representations.

This paper introduces a special issue of Cognition on lexical access in speech production. Over the last quarter century, the psycholinguistic study of speaking, and in particular of accessing words in speech, received a major new impetus from the analysis of speech errors, dysfluencies and hesitations, from aphasiology, and from new paradigms in reaction time research. The emerging theoretical picture partitions the accessing process into two subprocesses, the selection of an appropriate lexical item (a "lemma") from the mental lexicon, and the phonological encoding of that item, that is, the computation of a phonetic program for the item in the context of utterance. These two theoretical domains are successively introduced by outlining some core issues that have been or still have to be addressed. The final section discusses the controversial question whether phonological encoding can affect lexical selection. This partitioning is also followed in this special issue as a whole. There are, first, four papers on lexical selection, then three papers on phonological encoding, and finally one on the interaction between selection and phonological encoding.

Female

Spatial reference in weightlessness: perceptual factors and mental representations.

The role of gravity in spatial coordinate assignment and the mental representation of space were studied in three experiments, varying different perceptual cues systematically: the retinal, the visual background, the vestibular, and proprioceptive information. Verbal descriptions of visually presented arrays were required under different head positions (straight/tilt) and under different gravitational conditions (gravity present/gravity absent). The results of two experiments conducted with 2 subjects who participated in a space flight revealed that subjects are able to adequately assign positions in space in the absence of gravitational information, and that they do this by using their head-retinal coordinates as primary references. This indicates that they cognitively adapted to the perceptually new situation. The findings from a third experiment conducted with a larger group of subjects under a condition in which the gravitational information was present but irrelevant to the task being solved (subjects were in a horizontal supine position) show that subjects, in general, are flexible in using cues other than gravitational ones as references when the latter cannot serve as a referential system. These findings, together with the observation that consistent spatial assignment is possible even immediately after first exposure to the perceptually totally novel situation of weightlessness, seem to suggest that the mental representation of space, onto which given perceptual information is mapped, is independent of a particular percept.

Adult

Resolving perceptual conflicts: the cognitive mechanism of spatial orientation.

The cognitive mechanisms of spatial orientation were studied in an experiment varying different perceptual cues systematically: the retinal, the visual background, the vestibular, and the somatosensory information. Verbal descriptions of visually presented arrays were required under different head positions (straight/tilt) and under different gravity conditions (1 G/micro G). Results for two subjects clearly show that different coordinate systems are used under the two gravity conditions. Under 1 G it is the gravitational vertical which is chosen for primary reference, whereas under microgravity retinal information is primary. Conflicts between competing pieces of sensory information are solved by weighting the perceptual cues differently. The finding that consistent assignment can be made immediately after first exposure to weightlessness indicates that mental representations of space can be used independently of perceptual input parameters.

Cognition

Déjà vu?

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Cognition

Do speakers have access to a mental syllabary?

The first, theoretical part of this paper sketches a framework for phonological encoding in which the speaker successively generates phonological syllables in connected speech. The final stage of this process, phonetic encoding, consists of accessing articulatory gestural scores for each of these syllables in a "mental syllabary". The second, experimental part studies various predictions derived from this theory. The main finding is a syllable frequency effect: words ending in a high-frequent syllable are named faster than words ending in a low-frequent syllable. As predicted, this syllable frequency effect is independent of and additive to the effect of word frequency on naming latency. The effect, moreover, is not due to the complexity of the word-final syllable. In the General Discussion, the syllabary model is further elaborated with respect to phonological underspecification and activation spreading. Alternative accounts of the empirical findings in terms of core syllables and demisyllables are considered.

Adolescent