The Effects of Frequency and Predictability on Repetition in Children With Developmental Language Disorder.

Purpose Studies have shown that children with typical development (TD) respond to frequency and predictability when repeating nonidiomatic multiword sequences (e.g., go wash your hands). We extended these findings by explicitly examining the interaction between frequency and predictability in a repetition task for children with developmental language disorder (DLD) and children with TD. Method We created 48 four-word phrases, manipulating two factors: the frequency of occurrence of the entire four-word phrase (e.g., look in the mirror vs. look in the basket) and the predictability of the fourth word in the phrase given the preceding three words (e.g., corn on the ___ vs. look in the ___). These phrases were presented in a repetition task to 17 children with DLD (M age = 58.89 months), 19 same-age children with TD (M age = 59.79 months), and 17 younger children with TD matched to the DLD group on nonword repetition and mean length of utterance (M age = 38.94 months). Children's repetitions were judged for the presence or absence of word and morphological errors. Only the first three words of the sequence were scored (e.g., look in the). Results We found a main effect of sequence frequency, with high-frequency sequences being repeated more accurately than low-frequency sequences, modulated by a significant interaction with predictability, where the effect of sequence frequency was larger for sequences with high-predictability contexts than for sequences with low-predictability contexts. We also found a significant effect of group, with children with DLD demonstrating poorer overall performance, particularly when compared to the same-age group with TD. Conclusions Frequency and predictability are strong predictors of language production in children with TD. These factors also have effects for children with DLD, raising important clinical questions about the design of facilitative contexts for the teaching of difficult linguistic forms.