Angèle Brunellière

Behavioral and electrophysiological evidence for the impact of regional variation on phoneme perception

This event-related potential (ERP) study examined the impact of phonological variation resulting from a vowel merger on phoneme perception. The perception of the /e/-/epsilon/ contrast which does not exist in Southern French-speaking regions, and which is in the process of merging in Northern French-speaking regions, was compared to the /ø/-/y/ contrast, which is stable in all French-speaking regions. French-speaking participants from Switzerland for whom the /e/-/epsilon/ contrast is preserved, but who are exposed to different regional variants, had to perform a same-different task. They first heard four phonemically identical but acoustically different syllables (e.g., /be/-/be/-/be/-/be/), and then heard the test syllable which was either phonemically identical to (/be/) or phonemically different from (/bepsilon/) the preceding context stimuli. The results showed that the unstable /e/-/epsilon/ contrast only induced a mismatch negativity (MMN), whereas the /ø/-/y/ contrast elicited both a MMN and electrophysiological differences on the P200. These findings were in line with the behavioral results in which responses were slower and more error-prone in the /e/-/epsilon/ deviant condition than in the /ø/-/y/ deviant condition. Together these findings suggest that the regional variability in the speech input to which listeners are exposed affects the perception of speech sounds in their own accent.

The speakers’ accent shapes the listeners’ phonological predictions during speech perception

This study investigates the specificity of predictive coding in spoken word comprehension using event-related potentials (ERPs). We measured word-evoked ERPs in Catalan speakers listening to semantically constraining sentences produced in their native regional accent (experiment 1) or in a non-native accent (experiment 2). Semantically anomalous words produced long-lasting negative shift (N400) starting as early as 250 ms, thus reflecting phonological as well as semantic mismatch. Semantically expected but phonologically unexpected (non-native forms embedded in a native context) produced only an early (∼250 ms) negative difference. In contrast, this phonological expectancy effect failed for native albeit phonologically unexpected target words embedded in a non-native context. These results suggest phonologically precise expectations when operating over native input, whilst phonologically less specified expectations in a non-native context. Our findings shed light on contextual influence during word recognition, suggesting that word form prediction based on context is sensitive and adaptive to phonological variability.

Tracking the time course of word-frequency effects in auditory word recognition with event-related potentials.

Although the word-frequency effect is one of the most established findings in spoken-word recognition, the precise processing locus of this effect is still a topic of debate. In this study, we used event-related potentials (ERPs) to track the time course of the word-frequency effect. In addition, the neighborhood density effect, which is known to reflect mechanisms involved in word identification, was also examined. The ERP data showed a clear frequency effect as early as 350 ms from word onset on the P350, followed by a later effect at word offset on the late N400. A neighborhood density effect was also found at an early stage of spoken-word processing on the PMN, and at word offset on the late N400. Overall, our ERP differences for word frequency suggest that frequency affects the core processes of word identification starting from the initial phase of lexical activation and including target word selection. They thus rule out any interpretation of the word frequency effect that is limited to a purely decisional locus after word identification has been completed.

Visual information constrains early and late stages of spoken-word recognition in sentence context.

Audiovisual speech perception has been frequently studied considering phoneme, syllable and word processing levels. Here, we examined the constraints that visual speech information might exert during the recognition of words embedded in a natural sentence context. We recorded event-related potentials (ERPs) to words that could be either strongly or weakly predictable on the basis of the prior semantic sentential context and, whose initial phoneme varied in the degree of visual saliency from lip movements. When the sentences were presented audio-visually (Experiment 1), words weakly predicted from semantic context elicited a larger long-lasting N400, compared to strongly predictable words. This semantic effect interacted with the degree of visual saliency over a late part of the N400. When comparing audio-visual versus auditory alone presentation (Experiment 2), the typical amplitude-reduction effect over the auditory-evoked N100 response was observed in the audiovisual modality. Interestingly, a specific benefit of high- versus low-visual saliency constraints occurred over the early N100 response and at the late N400 time window, confirming the result of Experiment 1. Taken together, our results indicate that the saliency of visual speech can exert an influence over both auditory processing and word recognition at relatively late stages, and thus suggest strong interactivity between audio-visual integration and other (arguably higher) stages of information processing during natural speech comprehension.

To What Extent do we Hear Phonemic Contrasts in a Non-native Regional Variety? Tracking the Dynamics of Perceptual Processing with EEG

This combined ERP and behavioral experiment explores the dynamics of processing during the discrimination of vowels in a non-native regional variety. Southern listeners were presented with three word forms, two of which are encountered in both Standard and Southern French ([kot] and [kut]), whereas the third one exists in Standard but not Southern French ([kot]). EEG recordings suggest that all of the word pairs were discriminated by the listeners, although discrimination arose about 100ms later for the pairs which included the non-native word form than for those which contained word forms common to both French varieties. Behavioral data provide evidence that vowel discrimination is sensitive to the influence of the listeners’ native phonemic inventory at a late decisional stage of processing.

Pre-attentive and attentive processing of French vowels

This study aimed at investigating the effects of acoustic distance and of speaker variability on the pre-attentive and attentive perception of French vowels by French adult speakers. The electroencephalogram (EEG) was recorded while participants watched a silent movie (Passive condition) and discriminated deviant vowels (Active condition). The auditory sequence included 4 French vowels, /u/ (standard) and /o/, /y/ and /ø/ as deviants, produced by 3 different speakers. As the vowel /o/ is closer to /u/ than the other deviants in acoustic distance, we predicted smaller mismatch negativity (MMN) and smaller N1 component, as well as higher error rate and longer reaction times. Results were in line with these predictions. Moreover, the MMN was elicited by all deviant vowels independently of speaker variability. By contrast, the Vowel by Speaker interaction was significant in the Active listening condition thereby showing that subtle within-category differences are processed at the attentive level. These results suggest that while vowels are categorized pre-attentively according to phonemic representations and independently of speaker variability, participants are sensitive to between-speaker differences when they focus attention on vowel processing.

Early and automatic syntactic processing of person agreement

Mismatch negativity, an index of automatic cerebral activity in response to novel stimuli, was used to determine the onset of morphosyntactic processing in French. Stimuli were four two-word sentences made up of a pronoun (first or second person) and a verb (first or second person). Verb forms differed only in the inflectional suffix, which made the sentences either syntactically correct or incorrect. The mismatch negativity response was found to be modulated by the grammaticality of the agreement relation at 50–140 ms after inflection onset, corroborating the previous finding that morphosyntactic processing occurs early and out of the focus of attention. The role of the pronoun–suffix association probabilities in determining the observed timing of morphosyntactic processing is discussed.

Does Imitation Facilitate Word Recognition in a Non-Native Regional Accent?

We asked to what extent phonetic convergence across speakers may facilitate later word recognition. Northern-French participants showed both a clear phonetic convergence effect toward Southern French in a word repetition task, and a bias toward the phonemic system of their own variety in the recognition of single words. Perceptual adaptation to a non-native accent may be difficult when the native accent has a phonemic contrast that is associated with a single phonemic category in the non-native accent. Convergence toward a speaker of a non-native accent in production may not prevent each speaker’s native variety to prevail in word identification. Imitation has been found in previous studies to contribute to predicting upcoming words in sentences in adverse listening conditions, but may play a more limited role in the recognition of single words.

ERP correlates of lexical analysis: N280 reflects processing complexity rather than category or frequency effects.

In the context of language processing, the N280 is an anterior negative event-related potential profile associated with the lexical categorization of grammatical function words versus content words. Subsequent studies suggested that this effect was related to word statistics including length and frequency in the lexicon. The current research tests the hypothesis that the N280 effect is related to an index of grammatical complexity. We recorded event-related potentials during a sentence reading task. Comparing content versus function words revealed the classic N280. Within function words, we compared the relative pronouns ‘qui’ and ‘que’ (which are identical for length and frequency) that in French indicate a subsequent simple (subject–subject) and complex (subject–object) relative clause, respectively. A left anterior N280 effect was observed only for ‘que’, supporting our hypothesis that the N280 reflects grammatical complexity that can be confounded with lexical category and statistical properties.

The interplay between semantic and phonological constraints during spoken-word comprehension

This study addresses how top-down predictions driven by phonological and semantic information interact on spoken-word comprehension. To do so, we measured event-related potentials to words embedded in sentences that varied in the degree of semantic constraint (high or low) and in regional accent (congruent or incongruent) with respect to the target word pronunciation. The data showed a negative amplitude shift following phonological mismatch (target pronunciation incongruent with respect to sentence regional accent). Here, we show that this shift is modulated by sentence-level semantic constraints over latencies encompassing auditory (N100) and lexical (N400) components. These findings suggest a fast influence of top-down predictions and the interplay with bottom-up processes at sublexical and lexical levels of analysis.