Word learning and Developmental Language Disorder: Rule learning and generalization

peer reviewedLes enfants ayant un trouble développemental du langage (TDL) présentent un vocabulaire réduit tant en quantité et qu’en qualité ainsi que des difficultés d’apprentissage de mots dont les causes restent méconnues. Cette recherche cible plus particulièrement le rôle des règles de catégorisation pour l’apprentissage lexical. A cette fin, une tâche de catégorisation implicite, comportant une règle, a été proposée à 17 enfants présentant un TDL et 17 enfants tout-venant d’âge scolaire. Cette tâche était suivie d’une tâche de généralisation visant à appliquer la règle apprise à de nouvelles sous-catégories. Les résultats montrent que, globalement, les enfants présentant un TDL ne se distinguent pas de leurs pairs contrôles. Toutefois, lorsque les performances des enfants de moins de neuf ans et de neuf ans et plus sont examinées séparément, des différences de groupe émergent chez les plus jeunes. Ces résultats suggèrent des habiletés préservées dans l’apprentissage de règles simples, basées sur un critère perceptif, chez les enfants présentant un TDL plus âgés mais ces aptitudes se mettent en place plus tardivement que chez les enfants tout-venant.Children with developmental language disorder (DLD) show quantity and quality vocabulary limitations. These difficulties are associated with word learning difficulties that remain misunderstood. Our research focuses on these children's ability to learn categorisation rules from a statistical learning perspective. An implicit categorisation task, in which a rule could be formulated, was proposed to 17 school-aged children with DLD and 17 typically developing children of the same age. This task was followed by a generalisation task, which measured the ability to apply the rule to new subcategories. The results showed globally preserved abilities for children with DLD. However, when a distinction was made between children under 9 and those aged 9 and over, differences emerged for the younger children. These results suggested preserved abilities in learning simple, perceptually based rules in older TDL children. However, it appeared that these abilities develop later than in the general population

Catégorisation et extension de mots chez les enfants avec un Trouble Développemental du Langage

Background: Word learning difficulties are often part of the deficits presented by children with Developmental Language Disorders (DLD). Word learning is known to be an inference-based processed, constrained by categorization, which helps the extension of new words to unfamiliar entities. These processes appear integrated in Bayesian models of cognition, which offer an interesting approach to explore this phenomenon. Indeed, learning takes place thanks to an inductive inference process that recruits prior knowledge and principles of statistical learning (detection of regularities). Our study aims at (1) defining if children with DLD can draw inductive inferences in a word-learning context using categorization; (2) defining the impact of prior knowledge on categorization tasks, i.e. defining if the task is easier when prior knowledge is available vs not available and exploring the strategies used by children to categorize unfamiliar stimuli. Methods: Thirteen children with DLD (between 6;0 and 9;0) and fifteen age-matched controls were exposed to a word-learning task in which they faced with exemplars of objects associated with pseudo-words. Objects belong to three categories spreading across three hierarchical levels. For each item, children chose among a set of test objects from the same categories which one(s) could be labelled the same (word extension). Our design included two parts: familiar and unfamiliar categories. Results and conclusions: Our results replicated previous work on familiar categories, which showed similar performances for children with and without DLD in a word extension task. However, differences between groups appeared for unfamiliar categories, suggesting difficulty in category-based inference and word extension when prior knowledge is not available to support the inference process of children with DLD

Preserved category-based inferences for word learning in school-aged children with Developmental Language Disorder

Word learning difficulties are often found in children with Developmental Language Disorder (DLD). Lexical patterns of difficulties appear to be well described in the context of DLD but very little research focuses on their underlying causes. Word learning is known to be an inference-based process, constrained by categorization, which helps the extension of new words to unfamiliar referents and situations. These processes appear integrated in Bayesian models of cognition, which supposes that learning relies on an inductive inference process that recruits prior knowledge and principles of statistical learning (detection of regularities). Taken together, these mechanisms remain underexplored in DLD. Our study aims to define whether children with DLD can draw inductive inferences in a word learning context using categorization. Twenty children with DLD (between 6;0 and 12;6), and 20 language-matched and 16 age-matched controls were exposed to a word learning task where they were given exemplars of objects associated with pseudo-words. The objects belonged to six categories spread across three hierarchical levels. For each item, the children chose which one(s), among a set of test objects from the same categories, could be labelled the same way (word extension). Results showed that school-aged children with DLD could extend new words to broader categories as well as their typically developing (TD) peers. Nevertheless, none of the DLD or TD children showed a specification of their categorization of familiar instances that referred to more restricted instances. Our study suggests preserved abilities in using conceptual knowledge in order to learn new words, which could be used as a compensative strategy in the context of therapy. Further studies are needed to investigate this ability in more complex learning contexts

Treatment for preschool age children who stutter: Protocol of a randomised, non-inferiority parallel group pragmatic trial with Mini-KIDS, social cognitive behaviour treatment and the Lidcombe Program-TreatPaCS.

peer reviewedStuttering is a speech disorder in which the flow of speech is disrupted by involuntary repetitions of sounds, syllables, words or phrases, stretched sounds or silent pauses in which the person is unable to produce sounds and sound transitions. Treatment success is the highest if stuttering is treated before the age of 6 years, before it develops into "persistent" stuttering. Stuttering treatment programs that focus directly on the speech of the child, like the Lidcombe Program, have shown to be effective in this age group. Mini-KIDS is also a treatment that focuses directly on the speech of the child. It is possible that capturing the increased brain plasticity at this age in combination with creating optimal conditions for recovery underlie these treatments' success rate. A treatment focusing on the cognitions, emotions and behaviour of the child, the social cognitive behaviour treatment (SCBT), is also frequently delivered in Belgium. In this study we want to compare, and collect data on the effectiveness, of these three treatment programs: Mini-KIDS, SCBT and the Lidcombe Program (protocol registered under number NCT05185726). 249 children will be allocated to one of three treatment groups. Stuttering specialists will treat the child (and guide the parents) with Mini-KIDS, the SCBT or the Lidcombe Program. They will be trained to deliver the programs meticulously. At 18 months after randomisation, the speech fluency of the child and the attitude of the child and parent(s) towards speech will be measured. It is expected that the three programs will achieve the same (near) zero levels of stuttering in nearly all children and a positive attitude towards speech at 18 months after the start of treatment. The amount of treatment hours to reach the (near) zero levels of stuttering will be compared between the different programmes. For families as well as for the health system this could generate important information

Inférences statistiques et développement langagier : Etude de l’apprentissage lexico-sémantique chez les enfants présentant un trouble développemental du langage

Apprendre des mots semble de prime abord naturel et aisé pour le jeune enfant. Pourtant, certains enfants, dont ceux qui présentent un trouble développemental du langage (TDL), rencontrent des difficultés à réaliser cet apprentissage. Ce travail de thèse s’intéresse aux capacités d’apprentissage lexical des enfants avec TDL et aux processus qui les sous-tendent. En adoptant une perspective bayésienne des apprentissages, nous avons proposé d’investiguer la réalisation d’inférences inductives, au service de l’apprentissage lexical, sous l’angle de l’implication des connaissances préalablement acquises par l’apprenant, ou connaissances a priori, et des aptitudes à détecter des régularités dans l’input et l’environnement, ou apprentissage statistique. Nos recherches mettent en évidence un profil de capacités préservées et altérées chez les enfants avec TDL, qui semble dépendre des conditions dans lesquelles les inférences sont réalisées. Plus précisément, les connaissances a priori et un faible degré de complexité des régularités à détecter semblent être des facteurs qui soutiennent la réalisation d’inférences, et représentent à tout le moins des conditions favorables aux apprentissages lexicaux des enfants avec TDL. A contrario, empêcher le recours aux connaissances a priori, ou encore augmenter la complexité des stimuli qui font l’objet de l’apprentissage statistique entraînent des difficultés d’apprentissage chez les enfants avec TDL comparativement à leurs pairs. Les résultats de nos recherches permettent de confirmer l’intérêt du cadre théorique choisi pour baliser les recherches liées à l’apprentissage lexical dans le TDL et d’identifier des conditions facilitatrices et des obstacles à cet apprentissage. De plus amples recherches sont toutefois nécessaires pour approfondir les résultats obtenus, explorer ces aptitudes dans d’autres contextes, et affiner notre compréhension des paramètres qui influencent l’apprentissage lexical de ces enfants.//Learning new words seems natural and easy for young children at first sight. However, some children, including those with a developmental language disorder (DLD), often encounter word learning difficulties. Our thesis focuses on the word learning abilities of children with DLD and the processes behind them. Using a Bayesian framework, we proposed to investigate how children make inductive inferences in order to learn new words, taking into account the involvement of knowledge previously acquired by the learner, i.e. prior knowledge, and the ability to detect regularities in the input and the environment, i.e. statistical learning. Our studies showed a pattern of preserved and impaired abilities in children with DLD, which seems to depend on the conditions under which inferences are made. More specifically, prior knowledge and a low level of complexity among the regularities to be detected, seem to be factors that support inferences and represent at least favourable conditions for word learning in children with DLD. Conversely, preventing the use of prior knowledge, or increasing the complexity of the stimuli for statistical learning, leads to learning difficulties among children with DLD compared to their peers. Our research results confirm the interest of the theoretical approach chosen to investigate word learning in children with DLD and identify facilitating conditions and obstacles to this learning. However, more research is needed to further investigate the results obtained, to explore these skills in other contexts, and to refine our understanding of the parameters that influence the lexical learning of these children

Apprentissage de nouveaux mots dans les troubles développementaux du langage : Catégorisation et généralisation

Les troubles développementaux du langage (TDL) sont caractérisés, entre autres, par des difficultés d'apprentissage lexical (Kan & Windsor, 2010). Depuis plusieurs années, nous assistons par ailleurs à l'émergence des théories bayésiennes des apprentissages, qui offrent un cadre intéressant pour étudier ces difficultés (Xu & Tenenbaum, 2007). En effet, elles postulent l'existence d'un puissant mécanisme d'inférences statistiques comme moteur des apprentissages, inférences réalisées par la combinaison de connaissances a priori (connaissances sémantiques p.ex.) et de la vraisemblance des données issues de l'environnement (Perfors, Tenenbaum, Griffiths & Xu, 2011). Ce mécanisme permettrait en outre des apprentissages rapides pouvant rapidement gagner en abstraction (Tenenbam, Griffiths & Kemp, 2006). A partir de ces théories, nous formulons l'hypothèse d'un déficit en inférences bayésiennes comme sous-jacent aux difficultés d'apprentissage lexical des enfants présentant un TDL. Plus précisément, nous nous sommes intéressés à la façon dont ils peuvent mobiliser ce mécanisme en inférences pour apprendre une règle de classification, et comment cette règle nouvellement apprise pouvait être généralisée pour étendre la catégorie créée. Nous nous sommes par ailleurs interrogés sur la capacité de ces enfants à utiliser des connaissances a priori dans une tâche de catégorisation. Pour ce faire, nous avons proposé une tâche d'apprentissage de nouveaux-mots, suivie d'une tâche de généralisation, et enfin d'une tâche d'apprentissage d'associations. Ces tâches ont été proposées à 20 enfants TDL ainsi qu'à des enfants tout-venant de même âge chronologique. Les résultats révèlent des aptitudes intègres chez les enfants TDL sur du matériel simple, ouvrant la possibilité d'observer ces mêmes compétences en contexte de complexité accrue

Word learning and Statistical Inference in Children with Developmental Language Disorder

Word learning is a language component that usually appears to be impaired in children with developmental language disorders (DLD) (Kan & Windsor, 2010). Despite it has long been studied, the underlying mechanisms of these difficulties remain unclear. For several years, however, we assist to the emergence of Bayesian learning models, which have been applied to account for word learning process (Perfors, Tenenbaum, Griffiths & Xu, 2011; Xu & Tenenbaum, 2007). According to these models, human beings are equipped with a strong mechanism of probabilistic, inductive inference (as opposed to frequentist approaches) which allows the learning processes to take place. Consider this, our study aims at exploring the hypothesis of a deficit of inductive inference in children with DLD as explaining the lexical difficulties they exhibit. We decided to create a novel word learning task inspired by Xu and Tenenbaum (2007). In this task, sets of one or three objects, which correspond to exemplars of novel words (e.g. dax), are presented to children with DLD. Once exposed to the exemplars, children have to pick out the other objects of the same type (other dax) from a larger set of new objects. Objects from several semantic categories and different levels of taxonomy are proposed. We can then explore the ability of children to learn and generalize through inductive inference by exploring the distributional pattern of responses across categories and levels of taxonomy. The ability of adjustment of the child’s responses given the condition (one or three examples) will also be taken into account in our analyses

Etudier les inférences inductives pour comprendre l'apprentissage de mots dans le trouble développemental du langage : Qu'est-ce qui est préservé et qu'est-ce qui ne l'est pas ?

Background: Children with DLD present with word-learning deficits. When learning new words, mapping forms to meanings involves making inferences to identify the adequate referent. These inferences could be guided by prior knowledge, such as previously acquired categories, as well as by statistical learning mechanisms that allow the detection of regularities. Some evidence emerge regarding word learning in children with DLD, but very little attention is paid to the ability to draw inductive inferences and use prior knowledge for learning. Aims: Our studies aimed to assess the ability to draw inductive inferences in children with DLD by investigating two aspects: the use of prior knowledge for learning and the ability to detect regularities in order to extract categorisation rules. Methods: We proposed two studies to school-aged children with DLD in order to study inductive inference during word learning. The first one consisted in a word extension task in two contexts, familiar and unfamiliar. This study aimed to investigate how children with DLD were able to extend new words and how prior knowledge would influence their performance. The second one proposed a progressive learning task in which children had to learn and then to generalise categorisation rules based on one or two features, either perceptual or relational. Results: The first study revealed that children with DLD were able to extend new words when prior knowledge was available (i.e. in a familiar condition) but relied more heavily on perceptual features compared with their typically developing (TD) peers when this knowledge was lacking (i.e. in an unfamiliar condition). The second study revealed that children with DLD were able to learn categorisation rules, either perceptual or relational, but to a lesser extent than their TD peers. Conclusions: These results extended previous findings revealing that school-aged children with DLD (1) had preserved word extension abilities when support was provided and (2) were able to learn a categorisation rule based on one perceptual feature in a context in which visual complexity is reduced. They will be discussed regarding what is known about word learning in children with DLD and the variables affecting this learning. Some implications for practice will also be highlighted

Learning words and categories: Lexical acquisition and Bayesian inference in children with Developmental Language Disorders

Developmental Language Disorders (DLD) are severe and pervasive language disorders characterized among other things by word learning impairment (Kan & Windsor, 2010). Despite a lot of studies have been conducted, we still lack for evidence regarding the mechanisms which underlie these difficulties. Emerging for several years, Bayesian theories of cognition offer an interesting approach to study this phenomenon (Xu & Tenenbaum, 2007). These theories establish inductive inference as a chore component of the learning processes (Perfors, Tenenbaum, Griffiths, & Xu, 2011). Inductive inference is based on the interaction of prior knowledge, which can be defined as knowledge and biases a learner is equipped with, and environmental data. According with those theories, we formulate the hypothesis of a deficit of inductive inference in children with DLD as explaining their word learning difficulties. More specifically, our aim is to determine if children with DLD can use prior knowledge in a similar way than their typically developing peers in order to make inferences. Furthermore, Bayesian learning theories can account for abstract acquisitions (Tenenbaum, Griffiths, & Kemp, 2006). A secondary goal thus consists to see if children with DLD can make inferences at two levels of abstraction when we control prior knowledge, namely first-order inferences and second-order inferences (Perry, Samuelson, Malloy, & Schiffer, 2010; Smith, Jones, Landau, Gershkoff-Stowe, & Samuelson, 2002). We decided to create a design in which twenty school-aged children with DLD are exposed to a learning association task, followed by a novel word learning task and a generalization task. In the learning association task, children are taught associations of physical properties with housing environment, in order to create a baseline for prior knowledge. In the novel word learning task, children are taught new categories of insects associated with non-words. Each category is determined by particular physical characteristics (e.g. characteristics/shape of hands) that children have to infer, and each kind of insect has to be linked to his particular housing according to his physical properties. This phase represents the first-order inference step. To evaluate second-order inference step children are administered a generalization task. In this task, they are presented with insects from new categories which have not been learned. We can explore by this way the biases children use to make inferences as well as their learning ability at two levels of abstraction. Performances of children with DLD will be contrasted with those of their typically developing peers, matched for age and non-verbal IQ (age-matched) or lexical development (language-matched)