Semantic diversity, frequency and the development of lexical quality in children's word reading

Frequency exerts a powerful influence on lexical processing but it is possible that at least part of its effect is caused by high frequency words being experienced in more diverse contexts over an individual's language experience. To capture this variability, we applied Latent Semantic Analysis on a 35-million-word corpus of texts written for children, deriving a measure of semantic diversity that quantifies the similarity of all the contexts a word appears in. Across three experiments with 6-13-year-old children involving reading aloud and lexical decision, we found a main effect of semantic diversity: high diversity words were responded to faster and read more accurately than low diversity words. Frequency, document count and age of acquisition were also significant predictors of reading behaviour. These findings demonstrate that contextual variability contributes to word learning and the development of lexical quality, beyond the effect of frequency.