Cross-situational word learning in children with and without DLD and its relation to lexical-semantic knowledge

Research indicates that statistical learning plays a role in word learning by enabling the learner to track the co-occurrences between words and their visual referents, a process that is named cross-situational word learning. Word learning is difficult for children with developmental language disorder (DLD). A deficit in statistical learning has been suggested to contribute to the language difficulties in these children. In the current study we investigate whether children with DLD have more difficulty than TD children with learning novel word–referent pairs based on cross-situational statistics in an implicit task, and whether this ability is related to their lexical-semantic skills. Moreover, we look at the role of variability of the learning environment. In our implicit cross-situational word learning task, each trial in the exposure phase was in itself ambiguous: two pictures of unknown objects were shown at the same time and two novel words were played consecutively, without indicating which word referred to which object. However, as every word occurred with its correct referent consistently, the children could learn the word–referent pairs across trials. The children were not explicitly instructed to learn the names of new objects. As an on-line measure of learning, eye-movements were recorded during the exposure phase. After exposure, word–referent knowledge was also tested using multiple choice questions. Different measures of lexical-semantic knowledge were administered to the children with DLD, as well as tasks measuring non-verbal intelligence and phonological processing. Contextual variability (the number of different distractors with which a particular word–referent pair occurs across trials) was manipulated between subjects by constructing two types of exposure conditions: low contextual diversity vs. high contextual diversity. Both groups of children performed significantly above chance level on the test phase, but the TD children significantly outperformed the children with DLD. This indicates that children with DLD have more difficulty with implicit cross-situational word learning. We found no significant effect of contextual diversity. The eye-tracking data revealed some evidence of online learning, but no differences between groups. The regression analyses did not reveal any significant predictors of off-line or on-line cross-situational word learning ability.