Relation between early language exposure and vocabulary size with literacy development in a computational model of reading

Relation between early language exposure and vocabulary size with literacy development in a computational model of reading

First Author: Ya-Ning Chang -- University of Manchester
Additional authors/chairs: 
Padraic Monaghan; Stephen Welbourne
Keywords: Language Development, Reading development, Early Literacy, Vocabulary, Modeling of reading
Abstract / Summary: 

Purpose
Studies have shown that vocabulary knowledge is a key predictor of early literary. Children with a large vocabulary size at preschool age can acquire reading skills more quickly during formal schooling. However, the causal relations among vocabulary size, the quantity and variation in language exposure, and reading acquisition are not well known. We tested these causal relations in a computational model of reading.

Method
We trained and tested a connectionist model of reading learning to map between semantics, phonology, and orthography. We first exposed the model to spoken and meaning word forms, with different vocabulary sizes and quantities of exposure to these vocabularies, to simulate variety in pre-literacy language skills and quantity of language exposure. Then the model was exposed to written forms of words. We analysed the model’s reading fluency and comprehension performance by using generalized linear mixed effects models.

Results
The results showed that both vocabulary size and exposure had unique and positive effects on reading performance, with larger effects in reading comprehension than in fluency. A significant two-way interaction between vocabulary size and exposure in comprehension showed that literacy developed most effectively from extended exposure to a large vocabulary, however, poorest reading development followed from extended exposure to a small vocabulary.

Conclusions
We demonstrated that the link between vocabulary knowledge and literacy was modulated by amount of exposure to the vocabulary. Pre-literacy exposure was only beneficial when this was to a large, varied vocabulary, and could be an impediment when exposure was to a limited vocabulary.