The Role of Sleep-dependent Consolidation in Vocabulary Learning

Within our culturally and linguistically diverse society language skills are critical in fostering intercultural understanding and tolerance. The continued drive towards globalisation and increased labour mobility has also increased demand for high levels of competence in foreign languages (2). In 2002 the Department for Education (3) launched the national languages strategy which aims to increase the number of people studying languages. Since it is unfeasible to teach a wide range of languages in primary schools, a major part of this initiative involves creating more opportunities for adult learning.

While much research effort has been invested in understanding vocabulary acquisition in children, adult language acquisition has been relatively neglected. Learning a second language (L2) during adulthood is fundamentally different from native language (L1) acquisition in which words and concepts are acquired during roughly the same period of development allowing lexical forms and their relevant concepts to become tightly integrated. In contrast, L2 words acquired during adulthood must intrude upon an already well established lexical-semantic system as the learner attempts to anchor new lexical forms onto their existing knowledge structures. Understanding this process is important not only for advancing scientific knowledge of learning and memory, but also for informing educational practice.

During the PDF I will develop my PhD work which examines vocabulary learning during adulthood. My research has investigated a number of interrelated themes including a)how new words become interconnected with the established L1, b)how the representation and processing of novel words is influenced by vocabulary training method, c)factors that impact our ability to learn words, and d)how novel word representations change over time. During the PDF I will communicate my findings to research scientists and education practitioners via journal articles and conference presentations.

Project
Although it seems intuitive to assume that memory fades over time when information is not reinforced, some aspects of word learning may benefit from a period of consolidation. My PhD work indicates that while recognition of trained familiar items becomes weaker over time, recognition of trained novel words increases. Recent research suggests that sleep is associated with a qualitative shift in the way in which novel word forms are represented in the brain (4) highlighting the need to advance understanding of the role of sleep in learning and memory.

The recognition that sleep research is critically important to cognitive science has been met with surge of interest in the area in recent years, yet at present few UK researchers have the experience required to conduct sleep studies. During the PDF I will acquire these skills by conducting a small research project based on my PhD work. To further understanding of sleep-dependent consolidation, it is important to specify the conditions necessary for consolidation to occur. Although it has been suggested that effects of consolidation are best observed when the memory trace is initially weak (1), my research demonstrates that even when participants undergo very extensive training on novel word forms, evidence of consolidation can still be observed in recordings of electrical brain activity (ERP). Interestingly no effects of consolidation were observed in response to novel words that participants had seen during training, but were not instructed to learn. This suggests that mere exposure is not sufficient for memory consolidation to occur and that it may be dependent upon the participant making a conscious effort to learn items during training. The PDF project will examine the role of intention to learn on memory consolidation. This work is important for disambiguating inconsistent findings in the sleep and memory literature and may explain why under some circumstances, consolidation effects are not observed.