Studying inductive inference processes to understand word learning in children with developmental language disorder: What is preserved and what is not?

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.