Title: Effects of early acquisition, experience, and impairment on language processing: A computational model of reading through the lifespan
Funder: Economic and Social Research Council

Abstract: 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.


Research activity codes: 1.2 PSYCHOLOGICAL AND SOCIOECONOMIC PROCESSES;2.3 PSYCHOLOGICAL, SOCIAL AND ECONOMIC FACTORS
Health categories: MENTAL HEALTH;NEUROLOGICAL