Monitoring Different Phonological Parameters of Sign Language Engages the Same Cortical Language Network but Distinctive Perceptual Ones

Abstract

Abstract■ The study of signed languages allows the dissociation of sensorimotor and cognitive neural components of the language signal. Here we investigated the neurocognitive processes underlying the monitoring of two phonological parameters of sign languages: handshape and location. Our goal was to determine if brain regions processing sensorimotor characteristics of different phonological parameters of sign languages were also involved in phonological processing, with their activity being modulated by the linguistic content of manual actions. We conducted an fMRI experiment using manual actions varying in phonological structure and semantics: (1) signs of a familiar sign language (British Sign Language), (2) signs of an unfamiliar sign language (Swedish Sign Language), and (3) invented nonsigns that violate the phonological rules of British Sign Language and Swedish Sign Language or consist of nonoccurring combinations of phonological parameters. Three groups of participants were tested: deaf native signers, deaf nonsigners, and hearing nonsigners. Results show that the linguistic processing of different phonological parameters of sign language is independent of the sensorimotor characteristics of the language signal. Handshape and location were processed by different perceptual and taskrelated brain networks but recruited the same language areas. The semantic content of the stimuli did not influence this process, but phonological structure did, with nonsigns being associated with longer RTs and stronger activations in an action observation network in all participants and in the supramarginal gyrus exclusively in deaf signers. These results suggest higher processing demands for stimuli that contravene the phonological rules of a signed language, independently of previous knowledge of signed languages. We suggest that the phonological characteristics of a language may arise as a consequence of more efficient neural processing for its perception and production. ■

Signs for Developing Reading : Sign Language and Reading Development in Deaf and Hard-of-Hearing Children

“…In contrast to spoken language users (Marslen-Wilson, 1987), it may be the case that for sign language users, semantic representation does not provide any further constraints on the lexical target beyond the influence of phonology. Since semantic and phonological representations seem to independently support language processing in hearing adults and children (e.g., Dispaldro et al, 2011), earlier findings (e.g., Cardin et al, 2016) and the present findings suggest that the relationship between phonology and semantics might differ across sign language and spoken language. This may in turn have implications for language processing and development, but also cognitive development.…”

“…The phonology of a sign language often carries semantic information (Thompson, Vinson, Woll, & Vigliocco, 2012), and some earlier studies indicate that semantic information, in addition to phonological, does not influence the processing efficiency of sign-based stimuli in deaf adults (e.g., Cardin et al, 2016;Rudner et al, 2016). This may explain why no difference in performance was found between familiar and unfamiliar signs for DHH signing children in the present study.…”

“…These findings demonstrate that the processing of manual gestures changes with sign language experience. On the other hand, there are also brain imaging studies indicating that lexical manual gestures are processed more efficiently than non-lexicalized manual gestures both by signing and non-signing individuals (e.g., Cardin et al, 2016). Thus, regardless of knowledge of sign language, imitation of lexical in comparison to non-lexical manual gestures might be easier, possibly reflecting that domain general representational processes also influence imitation (Meltzoff & Moore, 1997).…”

“…A set consisting of three familiar signs, three unfamiliar signs, and three non-signs, was selected from an available data base of video recorded manual gestures (see Cardin et al, 2016;Orfanidou, Adam, McQueen, & Morgan, 2009;. Familiar signs were real signs in SSL, thus, invoking both phonological and semantic representations for DHH participants (i.e., vocabulary).…”

“…Thus, it seems that it is more demanding to process manual gestures than to break the phonological patterns of signed languages, even for individuals with no previous knowledge of sign language. As discussed above, this may indicate that the phonological characteristics of a language arise as a consequence of more efficient neural processing of its perception and production (c.f., Cardin et al, 2016).…”