Cristina Baus

Lexical access in Catalan Signed Language (LSC) production

This paper investigates whether the semantic and phonological levels in speech production are specific to spoken languages or universal across modalities. We examined semantic and phonological effects during Catalan Signed Language (LSC: Llengua de Signes Catalana) production using an adaptation of the picture-word interference task: native and non-native signers were asked to sign picture names while ignoring signs produced in the background. The results showed semantic interference effects for semantically related distractor signs and phonological facilitation effects when target signs and distractor signs shared either Handshape or Movement but phonological interference effects when target and distractor shared Location. The results suggest that the general distinction between semantic and phonological levels seems to hold across modalities. However, differences in sign language and spoken production become evident in the mechanisms underlying phonological encoding, shown by the different role that Location, Handshape, and Movement play during phonological encoding in sign language.

When does Iconicity in Sign Language Matter

We examined whether iconicity in American Sign Language (ASL) enhances translation performance for new learners and proficient signers. Fifteen hearing nonsigners and 15 proficient ASL–English bilinguals performed a translation recognition task and a production translation task. Nonsigners were taught 28 ASL verbs (14 iconic; 14 noniconic) prior to performing these tasks. Only new learners benefited from sign iconicity, recognising iconic translations faster and more accurately and exhibiting faster forward (English–ASL) and backward (ASL–English) translation times for iconic signs. In contrast, proficient ASL–English bilinguals exhibited slower recognition and translation times for iconic signs. We suggest iconicity aids memorisation in the early stages of adult sign language learning, but for fluent L2 signers, iconicity interacts with other variables that slow translation (specifically, the iconic signs had more translation equivalents than the noniconic signs). Iconicity may also have slowed translation performance by forcing conceptual mediation for iconic signs, which is slower than translating via direct lexical links.

On the effects of second language immersion on first language production

The present study was aimed at investigating how the effects of a second language (L2) immersion on first language (L1) production are modulated by lexical frequency and the cognate status of words. By means of a picture naming and a semantic fluency task, we longitudinally explored the changes in L1 performance of a group of immersed learners. Our results revealed slower naming latencies at the end than at the beginning of the immersion period but only for those pictures whose corresponding names were low frequency and non-cognates. Moreover, the semantic fluency task revealed a decrease in the percentage of non-cognate words produced at the end of the immersion period. The observed decline in the accessibility to L1 words after a short L2 immersion period is explained in terms of the general bilingual lexical access disadvantage and studies of L1 attrition in speech production. Specifically, the present findings are more in line with theoretical accounts that consider lexical difficulties to be the result of changes in the frequency of use of the L1 during a short L2 immersion period.

Neighbourhood density and frequency effects in speech production: A case for interactivity

In three experiments, we explore the effects of phonological properties such as neighbourhood density and frequency on speech production in Spanish. Specifically, we assess the reliability of the recent observation made by Vitevitch and Stamer (2006), according to which the neighbourhood effect in Spanish has a reverse polarity to that observed in other languages. In Experiment 1, we replicate Vitevitch and Stamers (2006) experiment, this time adding a control group. The same inhibitory neighbourhood effect found for both groups can not corroborate the hypothesis posited by Vitevitch and Stamer. In Experiment 2, our results show that native speakers of Spanish named pictures with words belonging to high density neighbourhoods faster than those belonging to low density neighbourhoods. In Experiment 3, we test for effects of neighbourhood frequency during lexical selection. Again, we find a facilitatory effect for words with a high-frequency neighbourhood. Together, the results of the present experiments suggest that lexical selection is facilitated by the number of neighbours and by neighbourhoods with higher frequency. These findings are consistent with the predictions of interactive models.

Electrophysiological evidence for phonological priming in Spanish Sign Language lexical access

Interactive activation models of lexical access assume that the presentation of a given word activates not only its lexical representation but also those corresponding to words similar in form. Current theories are based on data from oral and written languages, and therefore signed languages represent a special challenge for existing theories of word recognition and lexical access since they allow us to question what the genuine fundamentals of human language are and what might be modality-specific adaptation. The aim of the present study is to determine the electrophysiological correlates and time course of phonological processing of Spanish Sign Language (LSE). Ten deaf native LSE signers and ten deaf non-native but highly proficient LSE signers participated in the experiment. We used the ERP methodology and form-based priming in the context of a delayed lexical decision task, manipulating phonological overlap (i.e. related prime-target pairs shared either handshape or location parameters). Results showed that both parameters under study modulated brain responses to the stimuli in different time windows. Phonological priming of location resulted in a higher amplitude of the N400 component (300-500 ms window) for signs but not for non-signs. This effect may be explained in terms of initial competition among candidates. Moreover, the fact that a higher amplitude N400 for related pairs was found for signs but not for non-signs points to an effect at the lexical level. Handshape overlap produced a later effect (600-800 ms window). In this window, a more negative-going wave for the related condition than for the unrelated condition was found for non-signs in the native signers group. The findings are discussed in relation to current models of lexical access and word recognition. Finally, differences between native and non-native signers point to a less efficient use of phonological information among the non-native signers.

The temporal dynamics of first versus second language production

In this study we explored the temporal origin of processing differences between first and second language production. Forty highly proficient bilinguals named objects of high and low lexical frequency aloud for both L1 and L2 separately while event-related brain potentials (ERPs) were recorded. The first electrophysiological differences elicited by response language occurred at the same early P2 peak (∼140-220 ms) where we observed the onset of the lexical frequency effect, but only for those bilinguals who started naming in an L1 context and afterwards switched to an L2 naming context. The bilinguals who named objects in the reverse direction did not display a language effect in the ERPs. Taken together, the data show that the L2 naming disadvantage originates during the onset of lexical access and seems to be driven by both representational strength, which is lower for L2 words, and language control demands, which are higher for L2 words.

When does word frequency influence written production

The aim of the present study was to explore the central (e.g., lexical processing) and peripheral processes (motor preparation and execution) underlying word production during typewriting. To do so, we tested non-professional typers in a picture typing task while continuously recording EEG. Participants were instructed to write (by means of a standard keyboard) the corresponding name for a given picture. The lexical frequency of the words was manipulated: half of the picture names were of high-frequency while the remaining were of low-frequency. Different measures were obtained: (1) first keystroke latency and (2) keystroke latency of the subsequent letters and duration of the word. Moreover, ERPs locked to the onset of the picture presentation were analyzed to explore the temporal course of word frequency in typewriting. The results showed an effect of word frequency for the first keystroke latency but not for the duration of the word or the speed to which letter were typed (interstroke intervals). The electrophysiological results showed the expected ERP frequency effect at posterior sites: amplitudes for low-frequency words were more positive than those for high-frequency words. However, relative to previous evidence in the spoken modality, the frequency effect appeared in a later time-window. These results demonstrate two marked differences in the processing dynamics underpinning typing compared to speaking: First, central processing dynamics between speaking and typing differ already in the manner that words are accessed; second, central processing differences in typing, unlike speaking, do not cascade to peripheral processes involved in response execution.

The role of syllables in sign language production

The aim of the present study was to investigate the functional role of syllables in sign language and how the different phonological combinations influence sign production. Moreover, the influence of age of acquisition was evaluated. Deaf signers (native and non-native) of Catalan Signed Language (LSC) were asked in a picture-sign interference task to sign picture names while ignoring distractor-signs with which they shared two phonological parameters (out of three of the main sign parameters: Location, Movement, and Handshape). The results revealed a different impact of the three phonological combinations. While no effect was observed for the phonological combination Handshape-Location, the combination Handshape-Movement slowed down signing latencies, but only in the non-native group. A facilitatory effect was observed for both groups when pictures and distractors shared Location-Movement. Importantly, linguistic models have considered this phonological combination to be a privileged unit in the composition of signs, as syllables are in spoken languages. Thus, our results support the functional role of syllable units during phonological articulation in sign language production.

Brain structure is related to speech perception abilities in bilinguals

Morphology of the human brain predicts the speed at which individuals learn to distinguish novel foreign speech sounds after laboratory training. However, little is known about the neuroanatomical basis of individual differences in speech perception when a second language (L2) has been learned in natural environments for extended periods of time. In the present study, two samples of highly proficient bilinguals were selected according to their ability to distinguish between very similar L2 sounds, either isolated (prelexical) or within words (lexical). Structural MRI was acquired and processed to estimate vertex-wise indices of cortical thickness (CT) and surface area (CSA), and the association between cortical morphology and behavioral performance was inspected. Results revealed that performance in the lexical task was negatively associated with the thickness of the left temporal cortex and angular gyrus, as well as with the surface area of the left precuneus. Our findings, consistently with previous fMRI studies, demonstrate that morphology of the reported areas is relevant for word recognition based on phonological information. Further, we discuss the possibility that increased CT and CSA in sound-to-meaning mapping regions, found for poor non-native speech sounds perceivers, would have plastically arisen after extended periods of increased functional activity during L2 exposure.

LSE-Sign: A lexical database for Spanish Sign Language

The LSE-Sign database is a free online tool for selecting Spanish Sign Language stimulus materials to be used in experiments. It contains 2,400 individual signs taken from a recent standardized LSE dictionary, and a further 2,700 related nonsigns. Each entry is coded for a wide range of grammatical, phonological, and articulatory information, including handshape, location, movement, and non-manual elements. The database is accessible via a graphically based search facility which is highly flexible both in terms of the search options available and the way the results are displayed. LSE-Sign is available at the following website: http://www.bcbl.eu/databases/lse/.