Frequency of input effects on word comprehension of children with specific language impairment

Children with specific language impairment (SLI) are known to have limited lexicons. Previous studies implicate a possible processing problem, in the form of a limited ability to comprehend new words in settings that require Quick Incidental Learning (QUIL). This study investigates further the factors contributing to limited QUIL by examining the effects of input frequency and word type (nouns vs. verbs). In addition, immediate versus long-term memory was examined for possible problems with storage mechanisms. Subjects were 30 5-year-old SLI children with receptive and expressive language deficits and two comparison groups of normally developing children: 30 MLU-equivalent and 30 CA-equivalent. The subjects were randomly assigned to one of three experimental conditions in which they viewed video story presentations in which targeted words were embedded. The conditions varied by number of word presentations, 0, 3, or 10. The 0 condition was a control condition in which familiar words were presented. Children's word comprehension was tested immediately following viewing and again several days later. The findings confirm a strong frequency effect, but one that is influenced by group status, word type, and retention demands. There is evidence of a robust representational mapping ability for SLI, which is at the same time modulated by a minimum input constraint and apparent problems with storage into long-term memory.