Rôle du dialogue et de la co-construction du discours dans l’acquisition de la morphosyntaxe: un processus interactionnel et dialogique

RÉSUMÉ Cet article a pour objectif d’illustrer les apports, pour la description de l’acquisition des aspects morphosyntaxiques, d’une approche croisant une perspective “linguistique de l’acquisition” avec la perspective dialogique élaborée à partir des travaux de Bakhtine. La première approche décrit l’interaction comme étant le principal vecteur des processus d’acquisition de la structuration syntaxique, avec une attention particulière portée aux phénomènes d’adaptation de l’adulte aux essais de l’enfant, et aux reprises faites par celui-ci. En parallèle, une approche dialogique de l’acquisition se focalise sur la façon dont la co-construction du discours par les deux interlocuteurs amène l’enfant à mobiliser et acquérir des compétences linguistiques pour partager et construire les significations qui font l’objet du discours. Nos analyses portent sur des séquences conversationnelles entre adultes et enfants âgés de 2 à 4 ans, tout-venant et atypique. Elles illustrent comment le dialogue et ses phénomènes inter-discursifs, combinés aux mécanismes interactionnels de la reprise, sont constituants des processus d’acquisition langagière.


Introduction
The current landscape of theories in language acquisition reveals that there are both a multiplicity of approaches debating with one another, and antagonistic perspectives. In our view, the essential feature for making an epistemological distinction between the different types of approach appears to be the role attributed to children's linguistic and social environment in language acquisition processes. While some perspectives focus on the maturation-based and innate dimension of language development, others mainly describe the general and specific cognitive processes involved in language acquisition, and give more or less importance to language functions and uses; finally, others take a socio-cultural perspective, according to which the interaction between a child and the adults around him/her significantly contributes, at different levels, to his/her language acquisition process.
Children's linguistic environment has been described as a mere trigger for innate structures, as input submitted to language processing mechanisms, or as an inseparable element of the social dimension of language and its acquisition; the different ways of considering this issue seem to form a continuum from generative approaches to socio-interactionist approaches (for a review on this issue, see Karmiloff & Karmiloff-Smith, 2001).
All content of Bakhtiniana. Revista de Estudos do Discurso is licensed under a Creative Commons attribution-type CC-BY 4.0 However, the interactionist approach is not homogenous and gathers theories with specific views and analyses concerning the role of interaction between child and adult in language acquisition. These differences reflect various concerns with respect to the different aspects of language and dialogical situations. While some examine the influence of usage on language development in adult-child interactions (TOMASELLO, 2003), others focus on the contribution of specific conversational modalities (CLARK, 2014;VENEZIANO & PARISSE, 2010), or analyse the role and acquisition of dialogical properties as a support for language acquisition FRANÇOIS, 2005;SALAZAR ORVIG et al., 2010, 2013; finally, some give a central role to the strong link between the structuration of thought and of language, which is displayed by the syntactic dimension of language, as it is experienced by children within the context of adapted interactions with an adult (CANUT et al., 2012;CANUT et al., 2017;LENTIN, 2009LENTIN, [1998).
Thus, although the foundations of interactionist research are based on the work of Wallon, Vygotsky, Bakhtin and Bruner, the fact remains that each orientation mainly relies on one of these approaches for its analyses, from the most dialogical ones, which draw on Bakhtin's ideas, to the most structural ones, which rely more on Vygotsky's views (FRANÇOIS, 1989).
These approaches are globally compatible and propose intersecting descriptions of adult-child interactions with respect to the co-construction of meaning between child and adult, the acquisition of language functions and uses (pragmatic and discursive aspects), and the acquisition of structural aspects (morpho-syntax). However, it appears that these aspects of language are most often studied separately, the reason why we propose the present article.
While Acquisition Linguistics allows for the structural analysis of repeats and recasts in adult-child interactions, dialogism enables to grasp inter-discursive phenomena, such as echoing, or analysable traces of previous discourse (BRES, 2017). Our goal is therefore to highlight the benefit of combining the structural approach with the dialogical approach in order to better understand the interactional processes of language acquisition, taking as an example the acquisition of the morpho-syntactic dimension of language. This means that interactions and their functioning must be taken into account both from a formal perspective on adult and child discourse, and in terms of usage and dialogical processes.
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Interaction and Language Development
All the studies that take an interactionist perspective on language development use notions from other complementary approaches to refine their analysis of the functioning of adult-child dyads, like for example Acquisition Linguistics, which relies on work carried out in sociolinguistics CANUT et al., 2018;LENTIN, 2009LENTIN, [1998), or other approaches based on a dialogical perspective (SALAZAR ORVIG, 2017).
Multiple elements are in play in language interactions involving an adult and a child, from a language acquisition point of view, but also from that of the very functioning of communication. Whether the adult is a parent, an educator, a teacher or a therapist, he/she always speaks within particular discourse contexts (explanations, narrations, orders, descriptions, etc.), with the aim to adapt, in a more or less conscious and systematic way, to the comprehension and production abilities of the child (DE PONTONX et al., 2017). This adaptation allows for the maintenance of communication, facilitates the circulation of meanings and forms, and gives children a true status of interlocutor (DE PONTONX et al., 2019). Adults therefore provide a support to children, not only through linguistic scaffolding, but also through scaffolding linked to the management and carrying out of the task (BRUNER, 1983;1 DE WECK & SALAZAR ORVIG, 2019;WOOD, BRUNER, ROSS, 1976 SALAZAR ORVIG et al., 2013). Adults' linguistic scaffolding is usually performed using repeats and recasts of what children say (see for example Nelson et al., 1984;, consisting in keeping the meaning of utterances while showing the appropriate structural and usage conventions, which the children use but do not master. This use of language in context is therefore a way for children to experiment the functioning of conversations, the function and usage properties of language items, and the code of their language. These adult interventions respond to a communicative need and occur within the context of conversational continuity (VENEZIANO, 2005 discursive nature, they echo children's discourse, and therefore provide a support for language acquisition processes.
Although they all agree on the importance of scaffolding, interactional studies consider language acquisition either through its structural characteristics, or through its functional aspects. Our article thus combines two approaches we consider complementary: the dialogical approach and Acquisition Linguistics.

A Dialogical Approach to Language Acquisition
In a dialogical perspective, language acquisition is the result of children's involvement in situations and activities that give them the possibility to engage in one or several "language games," which are specific to these situations and activities (MASSON et al., 2020). Children first discover the usage characteristics of language when they interact with adults, and this then gradually leads them to acquire structural aspects (SALAZAR ORVIG, 2017, 2018. Using concepts mainly developed in Marxism and the Philosophy of Language (VOLOŠINOV, 1973), 3 the dialogical approach focuses on enunciation (or utterance), which "is constructed between two socially organised persons" (p.85). It considers that "verbal interaction is the basic reality of language" (p.94), which is materialised with verbal exchanges forming a dialogue between individuals. In the perspective of inter-discursive dialogism (BRES, 2017), the utterances produced by the different interlocutors form a chain: every utterance should be considered as an echo, a response to a previous utterance, as well as a source for a following utterance. A dialogical utterance thus implies that there are two speakers who reuse each other's words (explicitly or not) with a meaning in correspondence with the here and now (BRES & VERINE, 2002;SALAZAR ORVIG & GROSSEN, 2008). This results in a permanent dialogue between several types of discourse: that of oneself, and that of others.
During the process of language socialisation, children develop competences through contact with others' dialogues and through the discourse genres in which they are involved (VION, 1998). Discourse genres are more than mere production contexts; they define the functional and structural aspects of language that are used by speakers in a given situation.
All content of Bakhtiniana. Revista de Estudos do Discurso is licensed under a Creative Commons attribution-type CC-BY 4.0 They therefore contribute to the gradual elaboration of complex mental structures in children.
During the acquisition process, discourse genres become more complex, from primary to secondary genres (BAKHTIN, 1986). 4 Primary genres correspond to verbal exchanges and are already present in the first stages of children's development, whereas secondary genres correspond to more complex exchanges, which do not have an immediate context, in spoken or written language. For SCHNEUWLY (1998), the emergence of secondary genres does not mean that the primary ones disappear, but rather that they are reorganised and reassigned new meanings and perspectives.
Like the other interactionist approaches, the dialogical perspective considers language acquisition as a process that depends on the relations between children and their social environment: "The organising centre of any utterance, of any experience, is not within but outside -in the social milieu surrounding the individual being" (VOLOŠINOV, 1973, p.93). 5 In a dialogue, individuals coordinate and adjust with one another, maybe even selfadapt, in order to co-construct enunciation. This "enunciative polyphony" (VION, 2010) is manifested through recasts and repeats, which are always different form a previous utterance, even when they are identical repetitions, because they are marked by the co-enunciator's positioning (SALAZAR ORVIG & GROSSEN, 2008) and enable the circulation of the meaning of words according to the other's discourse. "A word is a bridge thrown between myself and another. If one end of the bridge depends on me, then the other depends on my addressee. A word is territory shared by both addresser and addressee, by the speaker and his interlocutor" (VOLOŠINOV, 1973, p.86). 6 With respect to our issue, this means, on the one hand, that children are considered to assimilate the words of their language through their use in dialogue, and, on the other, that one should examine children's recasts and repeats to find traces of such learning. The circulation of words makes discourses evolve, which leads to meanings that were not necessarily shared before the initiation of dialogue (BAKHTIN, 2013;7 BENDER, 1998 FRANÇOIS (1990)) between an expert (an adult) and a beginner (a child) is the element that enables to establish dialogue and, in a language acquisition perspective, the first uses of language. The progressive assimilation of language would thus be linked to the learning that occurs within children's Zone of Proximal Development (VYGOTSKY, 1986(VYGOTSKY, [1934) and through dialogue, where learners reuse, reshape and redirect their own discourse and that of others (CHAYNE & TARULLI, 1999). Inter-discursive dialogism therefore supports a dynamic learning process (GUIRAUD, 2017), and highlights the way in which children assimilate discourses coming from various spheres around them and share them with others in their first uses of language.
As a consequence, adult-child dialogue could be considered as the privileged space for the development of language, through the co-construction of shared meanings, and hence of thought, given that "It is not experience that organises expression, but the other way around expression organises experience. Expression is what first gives experience its form and specificity of direction" (VOLOŠINOV, 1973, p.85). 8 This point of view on the link between language and thought is also adopted by Vygotsky, as well as by Acquisition Linguistics.

Acquisition Linguistics
In Acquisition Linguistics, children's language is dependent on the language that they experience in their multiple exchanges with adults. There is no description of the language used in these contexts with respect to a written standard language. With a sociolinguistic approach that takes into account both the diversity of discourse genres (BRONCKART, 2014) and the contexts of enunciation (DEBAISIEUX & VERTALIER, 2014), it is possible to describe the target language as a set of diversified enunciative variants (LENTIN, 2009(LENTIN, [1998), on a continuum from the most spontaneous oral productions to the most formal version of written language. Each of these variants belongs to different discourse genres, and meets the cultural and practical requirements of the communication situation in which the two interlocutors are engaged. The functioning of language and its acquisition are therefore described in context and in situation, just as in dialogical approaches.
All content of Bakhtiniana. Revista de Estudos do Discurso is licensed under a Creative Commons attribution-type CC-BY 4.0 mechanisms supporting children's cognitive and linguistic activity. Adults offer, reuse, and reformulate language operations: "in a meaningful dialogical activity with adults, children gradually take what they are able to use in order to make their language productioncomprehension system work" 13 (LENTIN, 2009(LENTIN, [1998, p.47).
Amongst these mechanisms, reusing the other person's words plays an essential role.
Responding to children's language attempts, adults resume, reformulate children's production and thus inscribe themselves in an interaction both meaningful to the children and equally adapted. Such adults' resumptions, provided they are close to children's abilities, are located in a Zone of Potential Development. Within this context, children's production attempts participate in their language acquisition process. The effects of recasts and repeats on language acquisition are not always obvious when one examines the proceedings of a conversation, but traces are sometimes visible in adult-child exchanges (BERTIN, 2014; CANUT & VERTALIER, 2014, p.14): It is not possible to reach what is within the mind, however there may be observable elements indicating a rupture, a change point, or transformations, in the Vygotskian sense, which could be clues on how the mind functions. 14 These clues can be observed through children's reuse of language elements provided or reformulated by adults. The functioning of this mechanism of reciprocal reuse in adultchild interactions, and its effects on children's acquisition has been described for the acquisition of syntactic constructions , and the acquisition of certain grammatical morphemes (BERTIN, 2011(BERTIN, , 2014. Canut and Vertalier (2014) state that complex syntactic constructions first appear in children's productions in direct relation with adults' utterances: they immediately reuse the constructions proposed by their interlocutor, and then these constructions progressively appear in autonomous productions.
In the case of free morphology, Bertin (2011Bertin ( , 2014 shows how adults' recasts of children's attempts lead to a gradual change of children's initial productions. This can be seen as a clue that children understand that there is a mismatch between their productions and those of 13 In the original: "dans une activité dialogique signifiante avec l'adulte, l'enfant prend progressivement ce qu'il est en mesure d'utiliser pour faire fonctionner son système de production-compréhension langagière (personal translation)." 14 In the original: "s'il n'est pas possible d'atteindre l'intrapsychique, on peut relever des éléments indiquant des ruptures, des points de changement, des transformations, au sens vygotskien du terme, qui pourraient être des indices du fonctionnement interpsychique (personal translation)." adults (CLARK, 2010). The functioning of adult-child dialogues, which is characterised by mechanisms of reciprocal reuse and by functional and formal adaptation, therefore serves as a language acquisition framework. Adapted interactions in children's experience of language play a central role in their language acquisition process.
The two approaches presented above have similar views on certain epistemological and theoretical aspects, and also their own specificities. They focus on different dimensions of the functioning of interaction to explain language acquisition. However, the dialogical approach and Acquisition Linguistics could be combined to better describe the interactional processes of language acquisition. We therefore propose to analyse examples from adultchild interactions in the following section, using these two approaches for the description of the interactional phenomena responsible for language acquisition.

Analysis of Morpho-Syntactic Recasts and Repeats in Adult-Child Dialogues
Our analyses are based on four excerpts of spontaneous interactions between adults and children with typical and atypical developments, aged between 2 and 4 years old. These excerpts come from corpora collected within the frame of our respective research work, in early child development (BERTIN, 2011), and on children with an atypical development .
Our aim is not to compare these corpora to outline similarities or differences between the children, but rather to show the effects of recognising children as conversation partners, and of dialogical behaviours between child and adult, on the use of structuring utterances of children presenting either typical or atypical development. To do so, our analyses focus on recasts and repeats, as we consider that the circulation of linguistic items between partners leads to children's reuse of lexical, morphological and syntactic elements, and that this reuse plays an essential role in their language acquisition. More specifically, we analyse the effect of adults' dialogical recasts and repeats echoing child productions on children's immediate reinvestment of syntactic structures, determiners and clitic subjects, during the interaction.
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Analysis of Adult-Child Exchange Sequences
Excerpts 1 and 2 come from a longitudinal corpus of filmed interactions between a therapist and a child around the age of 4 with a language delay. Excerpts 3 and 4 come from individual interactions between a researcher and a child aged 2 years and 5 months (excerpt 3), and between a mother and her 2-year-old child (excerpt 4). 15

Adult-Child with a Language Delay
We have selected two excerpts in which two types of tasks were proposed by the therapist: the creation of conventional sentences, and denomination. In both cases, the partners are engaged in discourse genres that are specific to the speech and language therapy situation (as metalinguistic activities; DA SILVA, 2014) and which impose constraints on the participants' verbal productions. Indeed, in the first excerpt, the two speakers are expected to produce subject-verb-(object)-type utterances, whereas in the second one, they should produce isolated words, or constructions like "c'est + X" (it's + X). Nevertheless, we will see that the speakers' intervention modes are not entirely induced, and therefore give participants a certain creative freedom (DE WECK, 2003).
Excerpt 1: RAY., aged 4 years and 1 month. 16 In this excerpt, the therapist aims to develop the the morpho-s competences of the child, who must create simple sentences by placing pictograms next to one another ("tu manges la soupe" 'you eat the soup' then "le chien mange la soupe" 'the dog eats the soup'). The excerpt is composed of two parts (parts 1 and 2). Between these parts, which are separated by an interval of around 1 minute, the speakers create together another sentence and speak about subjects which are not related to the activity. 15 In France, the General Data Protection Regulation (RGPD) (https://www.cnil.fr/fr/reglement-europeenprotection-donnees/chapitre1#Article4) entered into force on May 25, 2018. The data presented in this article was collected and processed before the entry into force of this law (see voir Bertin 2011, Masson, C., Laverdure, S., Calderaro-Viel, C, 2017) Furthermore, it should be noted that these collections were carried out with the explicit permission of the persons and / or their parents when it comes to minors. The presentation of the data complies, moreover, with Article 4 of the GDPR insofar as they do not provide any information that directly or indirectly identifies the individuals whose discourse is presented. 16 All the examples have been translated as literally as possible in order to maintain access to the formal aspects of the sequences that are analysed. These sequences are indicated in italic. The adult's scaffolding is first focused on carrying out the task. The therapist brings to the child's attention that he has made a mistake and that an element needs to be added (A4 and A5). As the child does not react, the adult resorts to two methods: on one side, she offers the missing word (A2: manger 'to eat'), on the other she adds information with two extensions (A6: manger avec la cuillère 'to eat with the spoon', and A8: manges la soupe 'eat the soup'). These methods appear to have a catalyst effect on the child's verbal productions as they are not only reused in E6, but also modified by the addition of "pas avec les doigts" 'not with the fingers,' which is partly repeated by the adult in A9 and reformulated in a syntactically complete utterance in A10. By giving precisions on the way that soup should be eaten with varied meaningful syntactic constructions, the adult offers the child the possibility to reinvest lexical and syntactic elements immediately. E6 shows how the child 17 In the original: "E1 -on <man(ge)> [>] ... / A1 -<mange> [<] (.) la soupe / A2 -alors (.) manger / A3mange / E2 -elle est là la soupe {place le pictogramme "soupe" à côté de celui de "manger"} / E3 -man(ge) ... / A4 -regarde (.) tu (.) soupe / E4 -tu (.) soupe / A5 -ça va pas ça il manque quelque chose là {pointe la phrase créée par E} / A6 -manger (.) manger avec la cuillère / {E prend le pictogramme "manger"} / A7oh ça va mieux (.) tu ... / E5 -tu ... / A8 -manges la <soupe> [<] / E6 -<man(ges)> [>] la (.) soupe (.) avec une cuillère pas avec les avec les doigts {montre ses doigts} / A9 -pas avec les doigts / E7 -avec les ... / A10 -on mange pas la soupe avec les doigts / Partie 1." All content of Bakhtiniana. Revista de Estudos do Discurso is licensed under a Creative Commons attribution-type CC-BY 4.0 has appropriated the adult's model. More precisely, we can see how the child relies on these elements to create an utterance that is not precisely identical to the ones previously produced by the adult. In this second part, the dialogue is on the same topic as in the beginning, with a change of referent ('you' is replaced by 'the dog eats'). When the adult proposes the construction "to eat with the fingers," 19 it reactivates the production described in part 1, which makes the child say that we "eat with the spoon." Interestingly, and contrary to the first part, the adult's linguistic scaffolding is rather minimal (for example, production of incomplete utterances in A5 and A6, of isolated words in A4 and A8). It therefore seems that one cannot explain the child's reuse of the construction "manger avec la cuillère" 'to eat with the spoon' by a support immediately provided in discourse. This excerpt shows the effects of the circulation of a word 18 In the original French: "A1 -c'est quoi? / E2 -papa man(ge) ... / A2 -bah <papa> [>]? {pointe le pictogramme "chien" sur la phrase créée par E} / E3 -<xxx> [<] / A3 -le chien ... / E4 -chien <man(ge)> [>] ... / A4 -<mange> [<] ... / E5 -man(ge) ... / A5 -de la soupe / E6 -soupe / A6 -ouais de la soupe / E7 -tiens ça c'est quoi ? {pointe un pictogramme} / A7 -ça ? {pointe le pictogramme "manger"} / E8oui / A8manger / E9 -man(g)er / A9 -manger tu vois avec <les doigts> [>] {montre le pictogramme "manger" et mime le geste de manger} / E10 -<man(g)er> [<] / A10 -manger {fait semblant de manger avec une cuillère} / E11 -[a] man(g)er avec la cuillère / A11oh ben oui on mange avec la cuillère t'as raison." 19 In the original: "manger avec les doigts." All content of Bakhtiniana. Revista de Estudos do Discurso is licensed under a Creative Commons attribution-type CC-BY 4.0 in a dialogue (here, "cuillère" 'spoon') and how a delayed reinvestment can emerge thanks to the dialogue co-constructed between the two participants. Furthermore, we can notice another subsequent reinvestment on the morpho-syntactic level through the child's production of a vocalic element, [a] (a filler syllable; 20 PETERS, 2001), which is reused and reinterpreted as "on" 'we' in A11.
The second excerpt shows a denomination task based on the combination of pictures and sounds. The child listens to various sounds that he could hear in his surroundings (vehicle noises, animal sounds, etc.) and then he must find the corresponding picture and name it.
This activity is focused on the comprehension and production of lexical items.

A19 -and mummy she puts the boots that's it when it rains right when the weather is bad it rains E9 -and mummy [e] puts boots 22
In this example, the adult's objective is to make the child guess the word pluie (rain) using a definition (A2: c'est de l'eau qui tombe du ciel 'it's some water that falls from the sky') and a picture based on which she thinks the child can infer the word (A3: la petite fille elle a quoi ? 'the little girl she has what?', A6: quand est-ce qu'on met les bottes? 'when do we put the boots?'). The answer is finally given by the adult, in the form of a complete utterance, which is repeated with a modifier (A8: il pleut très fort 'it rains very hard'), and then with the presentation of a new clue, that of the umbrella picture (A11: elle a pris un parapluie 'she has taken an umbrella'), which she then links to the child's personal experience (A12: maman des fois elle prend peut-être un parapluie 'mummy sometimes she takes maybe an umbrella'). This reference appears to be meaningful for the child, because it makes it possible for him to relate a generic situation to a specific experience (FRANÇOIS, 1989).
This probably explains why the child introduces a new referent (« papa » 'daddy') in E4. The adult therefore makes it possible for the child to experience a noun in a decontextualized situation through denomination as well as in context through the evocation of a personal experience. The developments of the dialogue show how the child attempts to construct other utterances based on the different elements circulating between the two participants (the boots, mummy, himself). While E6, E7, and E8 are incomplete, E9which reuses elements combined by the adult in a single utterance following isolated productions by the child (A19) is complete.
At the end of the dialogue, the child has not pronounced the expected word ("pluie" 'rain'), but he has nevertheless been able to construct meaning based on elements that are an appropriation process that is carried out during the exchange through adults' verbal and non verbal recasts/repeats and interpretations, language learning depends on the way in which adults envisage their discourse with respect to the knowledge already acquired by children, their participation and their interest in the dialogue (GUIRAUD, 2017;MASSON et al., 2017). In the excerpt above, the link between the dialogue and the child's experience is done through a narration where the subordinating element "quand" 'when' (i.e. an element introducing syntactic complexity) is used even though the child is not capable of producing such a construction. In our opinion, this type of complexity is present because of the discourse genre (personal storytelling) and because of the adult's representations concerning the child's supposed abilities.
This dialogue also offers the child the possibility to make morpho-syntactic attempts.
The word "bottes" 'boots' is produced several times and in different ways by the adult: "des bottes" 'indef-pl boots' (A5, A16), "les bottes" 'the boots' (A6, A15), "met les bottes" 'put the boots' (A19). This word is incomplete and in isolation in the child's production in E3, then after an incomprehensible part in E6, and finally after the filler syllable [e] in an utterance containing a verb in E9.
The analysis of these excerpts shows that a method based on the description of interdiscourse phenomena combined with that of linguistic structures sheds a new light on the acquisition processes of a child who has great difficulty acquiring language. The way in which he reuses the discourse of his environment displays how he elaborates his thought and language with the adult's scaffolding.

Adult-typical children
In spontaneous conversations between adults and typical children, the context created through the evocation of personal experience is similar for the dialogical construction of meaning, in particular through the circulation of associated formal elements between speakers. We will see the ways in which the children's reuses or echoes with respect to preceding discourses, in particular those of the interlocutor, constitute a support for the construction of their utterances. The following excerpt is a spontaneous exchange between a child aged 2 years and 5 months and an observer (the researcher). The adult asks questions to the child about an injury that she has on her forehead. the only thing that is changed is its morphological "dressing." The adult proposes the verbalisation of the potential event only after having agreed on the discourse object with the child during this exchange, with an utterance that is syntactically structured and reuses the word initially proposed by the child, and which answers the observer's initial question (A96: "tu t'es cognée dans la barrière" 'you yourself banged on the gate'). The meaning offered by the adult with this utterance is reused by the child in an utterance that has the same syntax and lexemes, with attempts on grammatical morphemes Dialogic syntax encompasses the linguistic, cognitive, and interactional processes involved when speakers selectively reproduce aspects of prior utterances, and when recipients recognize the resulting parallelisms and draw inferences from them. Its most visible reflex occurs when one speaker constructs an utterance based on the immediately co-present utterance of a dialogic partner (DU BOIS, 2014, p.1).
The syntactic structure of the two speakers' utterances display parallelisms, and in the present case these mechanisms enable the child to grasp information on the structure of her language, and the adult to respond to the child's attempts. However, it is interesting to see that the child reuses the lexeme she had first introduced, but she changes the form of the The second utterance is thus not just an echo or a mechanical repetition: it shows traces of the child's attempt to modify her previous discourse, and it is not strictly identical to the adult's utterance. In line with Guiraud (2017)'s observations on the learning of French as a second language concerning the role of inter-discourse dialogic processes in the global acquisition process of the target language, we consider these phenomena as clues of an ongoing acquisition process.
This exchange shows how the adult's reinvestment of previous discourses offers the child the morpho-syntactic and lexical means that she needs in order to express the meaning that she wishes to communicate. From a dialogical point of view, we can see how the two speakers' appropriation of the informational content brought by the two of them, and how their reuse of words leads to the construction of a structured utterance in terms of syntax.
The following excerpt is a dialogue between a mother and her two-year-old child, during which they recall a past event. It shows how the adult relies on the child's productions to offer him utterances that are longer in terms of syntax, with the appropriate morphology, while pursuing the dialogue and adding informational elements in order to maintain the narration. This excerpt illustrates how the child uses this information and plays his conarrator role. The end of this excerpt shows how the child and the adult use recasts and repeats to agree both on an informational element (the use of glue) and on its formal shape. Indeed, in E6 the child reuses the nominal phrase proposed by the adult in A4 ("...un peu de colle" '… a bit of glue') introduced by a filler syllable (E6: [økɔn] '[ø] glue'). In A6, the adult reuses this production and inserts it in an utterance reusing the preceding informational elements. Her recast appears to focus on morpho-syntactic aspects for this production (A6: "hum il a mis de la colle papa" 'hum he put some glue daddy'). The child reuses this nominal phrase another time, but with a different vowel (E6: [akɔn] '[a] glue'). Again no new information is added.
This sequence shows the role of recasts and repeats, in adults and children, for the acquisition of past experience narration from a dialogical point of view, and for the acquisition of morpho-syntactic elements from a structural point of view. In this perspective, both interlocutors' recasts and repeats appear to pertain to two categories: dialogue and structure. Considering recasts and repeats through their role in the acquisition of discourse behaviours and structural aspects allows for the description of language acquisition processes in their two-fold dimension: functional and formal.

Conclusion
Both the dialogical approach and the linguistic approach to language acquisition consider that interaction is the fundamental component of the functioning of language. Every interaction has a print of previous discourses: every utterance is linked to utterances that have already been produced or heard in different contexts. Observing these recast and repeat phenomena appears effective to have an insight on language acquisition processes.
A mixed analysis, which combines the structural dimension of Acquisition Linguistics and the functional dimension of the dialogical approach, enables to grasp the value, role and function of adult-child dialogues in the acquisition processes of morphosyntactic aspects of language, which are inseparable from the discourses and dialogues in which they appear. The complementarity of Bakhtin and Vygotsky's contributions appears as essential to address the interactional processes of language acquisition in all their complexity, and more generally language acquisition in its multifaceted nature. When adults reuse children's discourse, adapt to their supposed abilities and add their expertise, they are in the children's Zone of Proximal Development. As shown with our examples, these adapted recasts and repeats can sometimes lead children to change their productions in relation to their interlocutor's discourse. We thus consider that this dynamic phenomenon in discourses can correspond to what Guiraud (2017) describes when she uses the notion of inter-discursive dialogism to describe certain informal interactions between teachers and learners of French as a foreign language. Being in a child's Zone of Proximal Development means that adults must take into consideration the child's preceding discourses and address him/her by echoing his/her previous utterances in order to respond to his/her language production attempts. Finally, the description of a language acquisition process is