Michael Grosvald

Lexical access in American Sign Language: An ERP investigation of effects of semantics and phonology

That language forms (phonology) are arbitrarily related to their meanings (semantics) is often considered a basic property of human languages. Naturally occurring sign languages, however, often appear to conflate form and meaning. In this paper we examine whether this close coupling has processing consequences for lexical access. We examine the electrophysiological correlates of on-line sentence processing in an attempt to clarify the time-course of lexical access in American Sign Language. EEG was recorded while 17 native signers watched ASL sentences for comprehension. Participants were presented with sentences in which semantic expectancy and phonological form were systematically manipulated to create four types of violations. These four conditions of interest are contrasted to a baseline sentence with a preferred semantic ending. Two different effects were observed in early time windows. Evidence for an early effect of semantic pre-activation of plausible candidates (150-250 ms) was found, followed by a negativity associated with lexical selection (350-450 ms) for only phonologically related (-S, +P) and for only semantically related (+S, -P) signs. These findings provide evidence for a novel mapping of signal form and meaning that may be a unique signature of sign language. In the 450 to 600 ms window, all conditions showed an increased N400 with respect to the expected ending, suggesting greater difficulty in semantic integration with the established context. Overall, these findings provide important insights into the on-line processing of visual-manual language.

Interspeaker variation in the extent and perception of long-distance vowel-to-vowel coarticulation

Abstract The phenomenon of coarticulation is relevant for issues as varied as lexical processing and language change, but research to date has not determined with certainty how far such effects can extend. This study investigated the production and perception of anticipatory vowel-to-vowel (VV) coarticulation. First, 20 native speakers of English were recorded saying sentences containing multiple consecutive schwas followed by [i] or [а]. The resulting acoustic data showed significant VV coarticulatory influence up to three vowels before the context vowel, a greater distance than has been seen in previous studies. However, there was substantial variability among speakers in this regard. The perceptibility of these effects was then tested using behavioral methodology; even long-distance effects were perceptible to some listeners. Subjects’ coarticulatory production strength and perceptual sensitivity were positively, but only weakly, correlated. Although the very slowest speakers tended to coarticulate less than the rest, speech rate and coarticulatory strength were not significantly correlated for the group as a whole.

Handshape monitoring: Evaluation of linguistic and perceptual factors in the processing of American Sign Language

We investigated the relevance of linguistic and perceptual factors to sign processing by comparing hearing individuals and deaf signers as they performed a handshape monitoring task, a sign-language analogue to the phoneme-monitoring paradigms used in many spoken-language studies. Each subject saw a series of brief video clips, each of which showed either an American Sign Language (ASL) sign or a phonologically possible but nonlexical “nonsign,” and responded when the viewed action was formed with a particular handshape. Stimuli varied with respect to the factors of Lexicality, handshape Markedness, and Type, defined according to whether the action is performed with one or two hands and for two-handed stimuli, whether or not the action is symmetrical. Deaf signers performed faster and more accurately than did hearing nonsigners, and effects related to handshape Markedness and stimulus Type were observed in both groups. However, no effects or interactions related to Lexicality were seen. A further analysis restricted to the deaf group indicated that these results were not dependent upon subjects’ age of acquisition of ASL. This work provides new insights into the processes by which the handshape component of sign forms is recognised in a sign language, the role of language experience, and the extent to which these processes may or may not be considered specifically linguistic.

Perceptual invariance or orientation specificity in American Sign Language? Evidence from repetition priming for signs and gestures

Repetition priming has been successfully employed to examine stages of processing in a wide variety of cognitive domains including language, object recognition, and memory. This study uses a novel repetition priming paradigm in the context of a categorisation task to explore early stages in the processing of American Sign Language signs and self-grooming gestures. Specifically, we investigated the degree to which deaf signers’ and hearing nonsigners’ perception of these linguistic or nonlinguistic actions might be differentially robust to changes in perceptual viewpoint. We conjectured that to the extent that signers were accessing language-specific representations in their performance of the task, they might show more similar priming effects under different viewing conditions than hearing subjects. In essence, this would provide evidence for a visually based “lack of invariance” phenomenon. However, if the early stages of visual-action processing are similar for deaf and hearing subjects, then no such difference should be found. In both groups, we observed robust effects of viewpoint, indicating that repetition priming for identical prime–target pairs was greater than in cases of categorisation in which the prime and target varied in viewpoint. However, we found little evidence of group-related differences that could be interpreted as effects of perceptual invariance. These outcomes indicate that initial stages of sign and gesture recognition required for the categorisation of action types do not differ as a function of experience with a signed language. Instead, our data are consistent with and extend previously described visual-perceptual studies that have reported evidence for orientation-specific representations of human actions.

Exploring perceptual processing of ASL and human actions: effects of inversion and repetition priming.

In this paper, we compare responses of deaf signers and hearing non-signers engaged in a categorization task of signs and non-linguistic human actions. We examine the time it takes to make such categorizations under conditions of 180° stimulus inversion and as a function of repetition priming, in an effort to understand whether the processing of sign language forms draws upon special processing mechanisms or makes use of mechanisms used in recognition of non-linguistic human actions. Our data show that deaf signers were much faster in the categorization of both linguistic and non-linguistic actions, and relative to hearing non-signers, show evidence that they were more sensitive to the configural properties of signs. Our study suggests that sign expertise may lead to modifications of a general-purpose human action recognition system rather than evoking a qualitatively different mode of processing, and supports the contention that signed languages make use of perceptual systems through which humans understand or parse human actions and gestures more generally.

Long-Distance Coarticulation in Spoken and Signed Language: An Overview

This study explores the phenomenon of coarticulation in spoken and signed language, focusing in particular on long-distance effects, defined here as the articulatory influence of one phonetic element on another across at least one intervening segment. While a great deal of variability has been found among language users in the production and perception of such effects, the fact that long-distance coarticulation occurs at all has important theoretical implications. Recent work on sign language, together with relevant spoken-language results, offers new insights and raises interesting questions concerning the human language capacity in general.