Magnitude comparisons by children with specific language impairments: evidence of unimpaired symbolic processing

A size judgement task was used to investigate number processing skills in children with specific language impairments (SLI). Previous work with unimpaired adults and children has shown that when comparing the size of written numbers and other ordinal stimuli, there is a symbolic distance effect (SDE) such that decision time decreases with the size distance between items. This study examined the ability of children to judge stimulus pairs which were varied to contrast the processing of symbolic material against direct perceptual judgement and to test processing of numeric versus non-numeric material. Children with SLI were compared with a control group matched on verbal comprehension level. The children with SLI responded faster than the control subjects. The SLI and control groups showed similar SDE and a similar pattern of response across materials. No indication was found in the SLI data of any selective deficit in processing symbolic information. Findings are discussed in relation to theories of numeracy acquisition which acknowledge the importance of non-verbal representation of number meanings.