Effects of early acquisition, experience, and impairment on language processing: A computational model of reading through the lifespan

Early experience has a profound impact on cognitive and social development throughout the lifespan. Understanding these effects of early experience first requires uncovering the cognitive consequences of this experience on the way in which the human mind develops. In this project we test the influence of early experience on development of language, and the implications of the trajectory of early learning on language processing across the lifespan. We use computational models to align theoretical models of early experience affecting processing with behavioural observations, and track the effect of life experience on cognitive processing from acquisition through all stages of life.
We focus on the acquisition of words, because there is a large body of empirical literature on word processing at all life stages, well-established theoretical models of how words are processed in the cognitive system, as well as several computational implementations of word processing which facilitate direct comparisons between theories. In word processing, there is evidence that the "age of acquisition" (AoA) of a word has a profound impact on its storage and retrieval, such that early acquired words tend to have more associations with other words, and tend to be retrieved more quickly. Early words tend also to be more resistant to impairment as a consequence of neurodegeneration such as the consequences of Alzheimer's Disease.

This project will implement and test large-scale computational models of word processing that, as an innovation, introduce realistic properties of human language exposure to discover their consequences on how words are represented and processed. The model builds on previous connectionist models of reading, which are particularly appropriate for simulating development because they enable gradual accretion of knowledge over time, as a consequence of environmental exposure.

The models enable us to compare alternative theories about the locus of AoA in language - whether it is in the representations of words' meaning, or whether it is in the learning of mappings among meaning, sound, and written forms of words. The models also permit us to track whether word processing alters with age, by monitoring the involvement of meaning in the model over exposure simulating lifelong exposure to words. The models also enable us to test whether effects are generalisable to other languages, by testing the patterns of AoA in Spanish and English. Further, we can simulate cognitive impairment in the models and relate the effects of early experience in the impaired model to word processing in patients with degenerative diseases.

The modelling provides valuable theoretical insights into the way in which lifelong experience affects cognition. These insights in turn have potentially important impact in terms of understanding the effects of variability in early experience on social and cognitive development, as well as the factors affecting ageing and brain disease in cognitive performance. Thus, the models provide an important step towards proposing and testing the validity and effectiveness of interventions and protective factors against detrimental effects of initially reduced language exposure, and later language degeneration.

The proposed research has particular impact for education and health, having implications for quality of life, and addressing the ESRC's strategic priority of Influencing Behaviour and Informing Interventions. Our impact pathway ensures that the research in early influences on learning have outcomes in terms of societal impact.

Impact for Education
The project has impact potential for understanding the role of early experience and early language exposure for language processing across the lifespan. This emphasis on early experience has implications for predicting relative ease and difficulty of vocabulary acquisition as a consequence of previous learning. We will ensure impact of this research by:
Communicating with partners in Educational Authorities, teachers and speech therapists, NHS research network directors - via the NorthWest NHS Medicines for Children Research Network, and educational charities. These partners are already in contact with Lancaster University's Centre for Research in Human Development and Learning, as Advisors to this Centre, of which the PI is the Centre Director.
These partners have already been informed of the research, and as the project progresses presentations on the project's research will be given to this panel on an annual basis. Interacting with these partners will align applications in policy and practice with the research results, and this dialogue will assist in informing the research direction in terms of designing effective interventions and models of individual learning.
We have also approached a children's book publisher, but do not yet have formal agreement to involvement in the research project. As the project proceeds, we will engage a publisher partner to ensure that commercial and educational practices are informed by our research on early language acquisition.

Impact for Health
We have identified partners that are health practitioners and policy makers via connections to the Centre for Ageing Research at Lancaster University. These potential beneficiaries of the research include UK charities addressing challenges of ageing, and NHS representatives interested in ageing and neurodegeneration. We have established initial interest in the aims of our project, and we will increase this involvement to result in impact evidence through regular presentations and dialogues with these practitioners, through fora organised by the Centre for Ageing Research as well as Lancaster University's School of Health and Medicine annual events drawing together health policy makers and practitioners with academics. As with the educational partners, establishing the users' needs and priorities and using these to inform our research will lead to maximising impact.

Public engagement
The research is also of general interest and relevance to the broader public, particularly care-givers interested in the effect of early experience on language learning. Our impact plan includes regular press releases on the results of the studies, as well as outreach events in public understanding of science events. We will contribute to the British Science Festival, the Manchester Science Festival, and to local science organisation events, such as Café Scientifique.

Web-based presence
In addition to user-tuned research presentations and talks at public engagement events, we will also provide research reports and lay summaries of our project's activities that are accessible to various user groups - care-givers, educational and health practitioners, and commercial publishers.