Sleep & Vocabulary Development
Funded by the British Academy / Leverhulme Research Small Grants 2018-2020
Children are exposed to new words every day. They may be able to reproduce a new word immediately, but when does a new word become part of a child’s vocabulary (i.e. lexicalisation)? Recent research suggests that sleep supports lexicalisation in school- aged children, and that children’s existing knowledge (vocabulary size) may play a scaffolding role in supporting sleep-dependent lexicalisation. Sleep-dependent lexicalisation, however, has not been investigated in toddlers . In this project, I will examine the role of day-time and night-time sleep in lexicalisation in 2- year-old toddlers. Toddler's vocabulary size and non-verbal cognitive ability will be measured to allow teasing apart each of their contribution to individual differences in sleep-dependent lexicalisation.
Language-Mediated Visual Attention
What is the relationship between language and cognition? My research shows evidence that language can mediate the way we selectively attend to information in the visual world, which begins in infancy and toddlerhood.
Bias to Relevance
In a series of eye-tracking study, toddlers saw an array of pictures and heard labels spoken in child-directed speech. Upon hearing the word Carrot, toddlers looked more at the picture of a Car, which is phonologically similar to Carrot. Toddlers also looked more at the picture of Pear, indicating their knowledge and appreciation of Pear and Carrot being related by the semantic category of food. Interestingly, biased attention to phonologically- and semantically-relevant information was stronger in toddlers with a larger vocabulary. It is possible that toddlers who know more words are, overall, cognitively more advanced and therefore able to detect relevant information faster than those with a smaller vocabulary. In reverse, it is also possible that toddlers who are able to detect relevant information faster are able to learn faster, and accumulate a larger vocabulary.
Chow, J., Davies, A. M. A., & Plunkett, K. (2017). Spoken-word recognition in 2-year-olds: The tug of war between phonological and semantic activation. Journal of Memory and Language.
Backward Semantic Inhibition
What happens when we switch from one thought to another? My studies on backward semantic inhibition investigate the mental processes of switching attention between different semantic categories. In the experiment, toddlers hear the following words (category in parentheses) in a sequential manner: chair (furniture), coat (clothing), table (furniture). Attending to the word Coat leads to the inhibition of the mental representations of the previous word Chair. We know that chair and the category furniture has been inhibited because toddlers' and adults' subsequent response to the word Table (another furniture) is impaired. The effect of backward semantic inhibition is observed in adults and toddlers starting from 24-months,
In a recent study, we demonstrate that 18-month-olds can inhibit attention to a previously-attended but no longer relevant semantic category, but only if they have a relatively large vocabulary. Inhibitory processes are not only relatively late emerging in development, but are also relatively delayed in their online effects compared to facilitatory processes. A denser mental lexicon likely results in the formation of inhibitory links between lexical concepts, which allow toddlers to select and deselect concepts more efficiently.
Chow, J., Aimola Davies, A. M., Fuentes, L. J. & Plunkett, K. (accepted in 2018). The vocabulary spurt predicts the emergence of backward semantic inhibition in 18-month-old toddlers. Developmental Science.