The neural oscillatory markers of phonetic convergence during verbal interaction.

During a conversation, the neural processes supporting speech production and perception overlap in time and, based on context, expectations and the dynamics of interaction, they are also continuously modulated in real time. Recently, the growing interest in the neural dynamics underlying interactive tasks, in particular in the language domain, has mainly tackled the temporal aspects of turn-taking in dialogs. Besides temporal coordination, an under-investigated phenomenon is the implicit convergence of the speakers toward a shared phonetic space. Here, we used dual electroencephalography (dual-EEG) to record brain signals from subjects involved in a relatively constrained interactive task where they were asked to take turns in chaining words according to a phonetic rhyming rule. We quantified participants' initial phonetic fingerprints and tracked their phonetic convergence during the interaction via a robust and automatic speaker verification technique. Results show that phonetic convergence is associated to left frontal alpha/low-beta desynchronization during speech preparation and by high-beta suppression before and during listening to speech in right centro-parietal and left frontal sectors, respectively. By this work, we provide evidence that mutual adaptation of speech phonetic targets, correlates with specific alpha and beta oscillatory dynamics. Alpha and beta oscillatory dynamics may index the coordination of the "when" as well as the "how" speech interaction takes place, reinforcing the suggestion that perception and production processes are highly interdependent and co-constructed during a conversation.

Does orthographic training on a phonemic contrast absent in the listener's dialect influence word recognition?

This study examined whether the ability of southern French speakers to discriminate between standard French word forms such as /pike/ and /pikε/ can be improved by a training procedure in which participants were exposed to the orthographic representations of words forming /e/-/ε/ minimal pairs. The results of the training procedure showed that southern French speakers were able to perceive the /e/-/ε/ contrast in word final position when they associated words containing these vowels with their correct spelled form. Further, participants in a priming experiment, which was run immediately after training, no longer showed the priming effect on the trained minimal pairs that they had shown in the pre-test. However, a priming effect on the untrained minimal pairs was still observed immediately after training, showing that this training failed to transfer to untrained items. Finally, the benefits of the training procedure were no longer observed the day after training, since southern French speakers once again showed a priming effect on the trained minimal pair of words in a one day post-test. Implications of these findings for the locus of the difficulties of the southern French speakers with the word-final /e/-/ε/ contrast are discussed.

Gambling Problems Among Community Cocaine Users.

Cocaine use is highly prevalent and a major public health problem. While some studies have reported frequent comorbidity problems among cocaine users, few studies have included evaluation of gambling problems. This study aimed to estimate the prevalence of gambling problems and compare those who were at-risk gamblers with non-problem gamblers in terms of mental health problems, substance use problems, and some risk factors (i.e. family antecedents, erroneous perceptions and coping strategies) among individuals who smoke or inject cocaine. A total of 424 smoked or injected cocaine users recruited through community-based programs in Montreal (Quebec) completed the questionnaire, including the Canadian Pathological Gambling Index, the Composite International Diagnostic Interview, the CAGE, and the Severity Dependence Scale. Of the sample, 18.4 % were considered at-risk gamblers, of whom 7.8 % had problems gambling and 10.6 % were moderate-risk gamblers. The at-risk group was more likely to have experienced a recent phobic disorder and alcohol problems than the non-problem group. A multivariate analysis showed that, compared to those who were non-problem gamblers, the at-risk ones were more likely to have lost a large sum of money when they first started gambling, believed that their luck would turn, and gambled in reaction to painful life events. These results indicate the need to include routines for screening to identify gambling problem among cocaine users.

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.

Phonological abstraction before lexical access: New evidence from rime priming.

In this study, we focused on the rime priming effect and examined whether the frequency of rimes influences the size of the effect. Using the lexical decision task, we observed that the rime priming effect interacted with rime frequency with a stronger priming effect when the target words contained low-frequency rimes, in comparison with target words containing high-frequency rimes. Moreover, for both target words with low- and high-frequency rimes, a priming effect of similar magnitude was observed whether the primes and targets were pronounced by the same speaker or by different speakers. All together, these findings provide additional support for all the studies that plead for the existence of prelexical units and, in a more general way, for phonological abstraction prior to lexical access.

Conceptual alignment in a joint picture-naming task performed with a social robot.

In this study we investigated whether people conceptually align when performing a language task together with a robot. In a joint picture-naming task, 24 French native speakers took turns with a robot in naming images of objects belonging to fifteen different semantic categories. For a subset of those semantic categories, the robot was programmed to produce the superordinate, semantic category name (e.g., fruit) instead of the more typical basic-level name associated with an object (e.g., pear). Importantly, while semantic categories were shared between the participant and the robot (e.g., fruits), different objects were assigned to each of them (e.g., the object of 'a pear' for the robot and of 'an apple' for the participant). Logistic regression models on participants' responses revealed that they aligned with the conceptual choices of the robot, producing over the course of the experiment more superordinate names (e.g., saying 'fruit' to the picture of an 'apple') for those objects belonging to the same semantic category as where the robot produced a superordinate name (e.g., saying 'fruit' to the picture of a 'pear'). These results provide evidence for conceptual alignment affecting speakers' word choices as a result of adaptation to the partner, even when the partner is a robot.

Does training on a phonemic contrast absent in the listener's dialect influence word recognition?

Southern French listeners were trained on the word final Standard French /e/-/epsilon/ contrast that does not exist in their dialect. They learned to associate minimal pairs of new words with visual shapes. Although final training session performance was relatively high, the learning did not transfer to a lexical decision task with phonological priming. Thus successful training on a phonemic contrast did not guarantee the efficient use of this contrast in spoken word recognition tasks. These findings are discussed in light of abstractionist and exemplarist models.

[The effect of time-compressed speech on the perception of ataxic dysarthria: a report of two cases]. / Effet de l'accélération artificielle du signal de parole sur la perception des dysarthries cérébelleuses: à propos de deux cas.

AIM: In cerebellar dysarthria, the lack of precision in the articulatory motions leads to a temporal dysregulation with a decreased rate of speech. That is, our hypothesis is that the signal distortions are linked to the slowness of speech and that the acceleration of the rate improves the intelligibility of speech. PATIENTS AND METHOD: Two patients with a cerebellar pathology and an ataxic dysarthria participated in the present study. Speech intelligibility was assessed subjectively by a visual analog scale, and objectively by the constant-stimulus method associated with an identification task of a target phoneme in real time. The SOLA algorithm was used to accelerate the speech stimuli. 144 test sentences were created at 3 speed rates: 48 sentences at 'natural speed' (without compression, VN), 48 sentences at 'intermediate speed' (50% of the maximum rate, VI) and 48 sentences at 'maximum speed' (mean rate of a control group of speakers, VM). The 144 test sentences, in 3 experimental conditions, were distributed over 3 lists, each listener hearing each sentence only once; 8 subjects were assigned to each list. The sentences were presented in random order. A subjective assessment was performed for the whole corpus. The statistical analysis was performed with a mixed logit model for the subjective scores and the reaction time and with a chi2 test for the errors. RESULTS: For each patient, the odds of an improved intelligibility were significantly greater for the VI or VM condition than for the VN condition. The effect tended to be stronger for patient Z. From the VN to the VI condition, the satisfaction rate regarding the intelligibility increased from 78 to 87% for patient B and from 46 to 63% for patient Z (p = 0.03). There were fewer errors for the accelerated speech for patient Z. The acceleration had no effect on the reaction times in the phoneme identification task (F 2,(1,024) = 2.14, p = 0.12). CONCLUSIONS: In 2 cases of ataxic dysarthria, the perceived intelligibility was improved by a temporal acceleration of the speech disorders.

Speaking to a common tune: Between-speaker convergence in voice fundamental frequency in a joint speech production task.

Recent research on speech communication has revealed a tendency for speakers to imitate at least some of the characteristics of their interlocutor's speech sound shape. This phenomenon, referred to as phonetic convergence, entails a moment-to-moment adaptation of the speaker's speech targets to the perceived interlocutor's speech. It is thought to contribute to setting up a conversational common ground between speakers and to facilitate mutual understanding. However, it remains uncertain to what extent phonetic convergence occurs in voice fundamental frequency (F0), in spite of the major role played by pitch, F0's perceptual correlate, as a conveyor of both linguistic information and communicative cues associated with the speaker's social/individual identity and emotional state. In the present work, we investigated to what extent two speakers converge towards each other with respect to variations in F0 in a scripted dialogue. Pairs of speakers jointly performed a speech production task, in which they were asked to alternately read aloud a written story divided into a sequence of short reading turns. We devised an experimental set-up that allowed us to manipulate the speakers' F0 in real time across turns. We found that speakers tended to imitate each other's changes in F0 across turns that were both limited in amplitude and spread over large temporal intervals. This shows that, at the perceptual level, speakers monitor slow-varying movements in their partner's F0 with high accuracy and, at the production level, that speakers exert a very fine-tuned control on their laryngeal vibrator in order to imitate these F0 variations. Remarkably, F0 convergence across turns was found to occur in spite of the large melodic variations typically associated with reading turns. Our study sheds new light on speakers' perceptual tracking of F0 in speech processing, and the impact of this perceptual tracking on speech production.

Does Talker-Specific Information Influence Lexical Competition? Evidence From Phonological Priming.

In this study, we examined whether the lexical competition process embraced by most models of spoken word recognition is sensitive to talker-specific information. We used a lexical decision task and a long lag priming experiment in which primes and targets sharing all phonemes except the last one (e.g., /bagaR/"fight" vs. /bagaÆ·/"luggage") were presented in two separate blocks of stimuli. In Experiment 1, the competitor prime block was presented only once to listeners, and no modulation of the competitor priming effect as a function of a talker change between the primes and targets was observed. However, attenuation in the competitor priming effect in the case of a talker change between the primes and targets was observed in Experiment 2 in which the competitor prime block was presented five times to listeners. We discuss our findings in reference to hybrid models of spoken word recognition in which repetition of words with the same talker could be a key factor in the formation and access to talker-dependent representations.

The perception of the French /s/-/ʃ/ contrast in early Creole-French bilinguals.

One particularity of the Mauritian Creole language is that there is no contrastive distinction between the consonants /s/ and /ʃ/, which are both pronounced /s/ in Creole. In this study, we examined the identification performance of the /s/-/ʃ/ contrast by Mauritian Creole-French bilinguals who have been exposed to French before 7 years of age, and who have been raised in a highly Creole-French bilingual society. The results showed that most of our bilingual participants identify the /s/ and /ʃ/ consonants like native French speakers. It also appeared that the way in which the two consonants are categorized can be manipulated by introducing subtle changes in the information these participants were given about the identity of the speaker that produced the stimuli. Our results are in accordance with recent studies showing native-like performance in bilinguals on a categorization task and, importantly, extend these findings to speakers of a Creole language. In addition, these results show that speech sound categorization can be influenced by information about the speaker's social identity and thus argue for models that postulate rich speech sound representations.

How much imitation is there in a shadowing task?

Phonetic imitation, also called phonetic convergence, is currently at the heart of numerous investigations since it can inform us on both the nature of lexical representations and the link between production and perception processes in spoken language communication. A task that has been largely used to study phonetic imitation is the shadowing task, in which participants merely listen to and repeat isolated words. In this study, we examined the extent to which the phonetic convergence effect found when participants shadow auditory tokens, is an imitation of the speaker. We thus compared the phonetic convergence effect observed in a shadowing task to that observed when participants were explicitly instructed to imitate the productions they were exposed to. Although the phonetic convergence effect was greater when participants intentionally imitated the speaker's productions, shadowing and imitation instructions led to the same degree of convergence in a post-exposure task. Hence, the convergence effect found in a shadowing task and that found in an imitation task seem to share a general mechanism which is automatic and which taps into the long-term representations of the words in memory. At a more theoretical level, our results reinforce the claim that detailed auditory traces associated with perceived words are stored in memory and are later used for production.

Converging toward a common speech code: imitative and perceptuo-motor recalibration processes in speech production.

Auditory and somatosensory systems play a key role in speech motor control. In the act of speaking, segmental speech movements are programmed to reach phonemic sensory goals, which in turn are used to estimate actual sensory feedback in order to further control production. The adult's tendency to automatically imitate a number of acoustic-phonetic characteristics in another speaker's speech however suggests that speech production not only relies on the intended phonemic sensory goals and actual sensory feedback but also on the processing of external speech inputs. These online adaptive changes in speech production, or phonetic convergence effects, are thought to facilitate conversational exchange by contributing to setting a common perceptuo-motor ground between the speaker and the listener. In line with previous studies on phonetic convergence, we here demonstrate, in a non-interactive situation of communication, online unintentional and voluntary imitative changes in relevant acoustic features of acoustic vowel targets (fundamental and first formant frequencies) during speech production and imitation. In addition, perceptuo-motor recalibration processes, or after-effects, occurred not only after vowel production and imitation but also after auditory categorization of the acoustic vowel targets. Altogether, these findings demonstrate adaptive plasticity of phonemic sensory-motor goals and suggest that, apart from sensory-motor knowledge, speech production continuously draws on perceptual learning from the external speech environment.

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.

Regional differences in the listener's phonemic inventory affect semantic processing: A mismatch negativity (MMN) study.

Using the mismatch negativity (MMN) response, we examined how Standard French and Southern French speakers access the meaning of words ending in /e/ or /ε/ vowels which are contrastive in Standard French but not in Southern French. In Standard French speakers, there was a significant difference in the amplitude of the brain response after the deviant-minus-standard subtraction between the frontocentral (FC) and right lateral (RL) recording sites for the final-/ε/ word but not the final-/e/ word. In contrast, the difference in the amplitude of the brain response between the FC and RL recording sites did not significantly vary as a function of the word's final vowel in Southern French speakers. Our findings provide evidence that access to lexical meaning in spoken word recognition depends on the speaker's native regional accent.

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.

Speech perception engages a general timer: evidence from a divided attention word identification task.

Time is essential to speech. The duration of speech segments plays a critical role in the perceptual identification of these segments, and therefore in that of spoken words. Here, using a French word identification task, we show that vowels are perceived as shorter when attention is divided between two tasks, as compared to a single task control condition. This temporal underestimation pattern is consistent with attentional models of timing and hence demonstrates that vowel duration is explicitly estimated using a central general-purpose timer.

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 perception of phonemic contrasts in a non-native dialect.

This study examined the impact on speech processing of regional phonetic/phonological variation in the listener's native language. The perception of the /e/-/epsilon/ and /o/-/upside down c/ contrasts, produced by standard but not southern French native speakers, was investigated in these two populations. A repetition priming experiment showed that the latter but not the former perceived words such as /epe/ and /epepsilon/ as homophones. In contrast, both groups perceived the two words of /o/-/upside down c/ minimal pairs (/pom/-/p(uspide down c)m/) as being distinct. Thus, standard-French words can be perceived differently depending on the listener's regional accent.

Solution-phase parallel synthesis of substituted benzimidazoles.

A solution-phase parallel synthesis of o-phenylenediamines is described. These intermediates were then subsequently converted to benzimidazole scaffolds (three-point diversity) in excellent purities and yields. High-throughput purification of this multistep synthetic sequence was accomplished using polymer-bound scavengers and reagents and liquid-liquid extraction protocols.