Simulating SLI: General cognitive processing stressors can produce a specific linguistic profile

This study attempted to model specific language impairment (SLI) in a group of 6-year-old children with typically developing language by introducing cognitive stress factors into a grammaticality judgment task. At normal speech rate, all children had near-perfect performance. When the speech signal was compressed to 50% of its original rate, to simulate reduced speed of processing, children displayed the same pattern of errors that is reported in SLI: good performance on noun morphology (plural -s) and very poor performance on verb morphology (past tense -ed and 3rd-person singular -s). A similar pattern was found when memory load was increased by adding redundant verbiage to sentence stimuli. The finding that an SLI-like pattern of performance can be induced in children with intact linguistic systems by increasing cognitive processing demands supports the idea that a processing deficit may underlie the profile of language difficulty that characterizes SLI.