What Children with Developmental Language Disorder Teach Us About Cross-Situational Word Learning.

Children with developmental language disorder (DLD) served as a test case for determining the role of extant vocabulary knowledge, endogenous attention, and phonological working memory abilities in cross-situational word learning. First-graders (Mage = 7 years; 3 months), 44 with typical development (TD) and 28 with DLD, completed a cross-situational word-learning task comprised six cycles, followed by retention tests and independent assessments of attention, memory, and vocabulary. Children with DLD scored lower than those with TD on all measures of learning and retention, a performance gap that emerged in the first cycle of the cross-situational protocol and that we attribute to weaknesses in initial encoding. Over cycles, children with DLD learned words at a similar rate as their TD peers but they were less flexible in their strategy use, demonstrating a propose-but-verify approach but never a statistical aggregation approach. Also, they drew upon different mechanisms to support their learning. Attention played a greater role for the children with DLD, whereas extant vocabulary size played a greater role for the children with TD. Children navigate the problem space of cross-situational learning via varied routes. This conclusion is offered as motivation for theorists to capture all learners, not just the most typical ones.