Why do children with specific language impairment name pictures more slowly than their peers?

To examine the role of different cognitive processes in accounting for the slower naming times of children with specific language impairment (SLI) relative to peers with no language impairment (NLI), three tasks designed to stress different types of processing, were administered: naming pictures with the signal to respond presented at various delay intervals, naming following different durations of exposure to identical and unrelated primes, and vocally responding to nonlinguistic stimuli. Children with SLI, aged 4 to 9.5 years, were significantly slower than their NLI age peers on naming and on responding to nonlinguistic stimuli, but the effect of delay interval before naming and of duration of prime exposure before naming was similar for both groups. Results suggested that speed of naming is related to the slower nonlinguistic response processing of children with SLI and not to speed of their linguistic or perceptual processing. To examine differences in processing that might relate to pattern of language performance we examined responses of two subgroups of SLI. The subgroup of children whose language problems involved expressive but not receptive skills was not significantly slower than their NLI peers. The children whose problems involved both expressive and receptive language were significantly slower, but this was influenced by age. Findings are discussed in terms of language performance, age, task variables, and a generalized rate-limiting factor.