Effect of implicit and explicit 'rule' presentation on bound-morpheme generalization in specific language impairment

This study addressed whether generalization of a trained bound morpheme to untrained vocabulary stems differs between children with specific language impairment (SLI) and children with normal language (NL) under two controlled instructional conditions. Twenty-five children with NL and 25 children with SLI matched for age served as subjects. Contrasts between affixed and unaffixed words highlighted the affixation 'rule' in the 'implicit-rule' condition. The 'rule' was verbalized by the trainer in the 'explicit-rule' condition. Bimodal generalization results occurred in both subject groups, indicating that generalization was not incremental. Chi-square analyses suggested that the SLI group generalized the bound morpheme less often than the NL group under the explicit-rule training condition. The findings add to those that indicate children with SLI have a unique language-learning style, and suggest that the explicit presentation of metalinguistic information during training may be detrimental to bound-morpheme generalization by preschool-age children with SLI.