The slower the better? Does the speaker's speech rate influence children's performance on a language comprehension test?

The aim of this study was to examine the effects of speech rate on children's performance on a widely used language comprehension test, the Test for Reception of Grammar, version 2 (TROG'2), and to explore how test performance interacts with task difficulty and with the child's working memory capacity. Participants were 102 typically-developing Swedish-speaking children randomly assigned to one of the three conditions; the TROG'2 sentences spoken by a speech-language pathologist with slow, normal or fast speech rate. Results showed that the fast speech rate had a negative effect on the TROG'2 scores and that slow rate was more beneficial in general. However, for more difficult tasks the beneficial effect of slow speech was only pronounced for children with better scores on a working memory task. The interpretation is that slow speech is particularly helpful when children do not yet fully master a task but are just about to grasp it. These results emphasize the necessity of careful considerations of the role dynamic aspects of examiner's speech might play in test administration and favour digitalized procedures in standardized language comprehension assessment.