Word learning in early, middle and late adulthood

In the field of cognitive aging, it is well established that some cognitive functions remain relatively stable over the lifespan (e.g., long-term representations, automatic processes, implicit learning) while others progressively decline (e.g., executive control, memory maintenance/retrieval, and speed). Language use shows a mixed aging trajectory as well: Phonological, lexical, semantic and syntactic knowledge is relatively preserved, whereas the ease of access to that knowledge and control over its activation tend to degrade with age. How this dissociation affects the dynamics and efficiency of word learning over the lifespan is unclear.

The purpose of this research programme is to investigate the age-related stability vs. decline of several key word-learning mechanisms that have been documented in the word-acquisition literature in infancy and childhood, and to establish the extent to which compensatory trade-offs (e.g., reliance on stored knowledge) can stave off the decline of learning mechanisms that involve a greater degree of executive control and explicit computation. A better understanding of how the mechanisms underpinning word learning change over the lifespan has important consequences for older adults' quality of life. Indeed, owing to today's increased life expectancy and the expectation that many of those additional years will be spent in relatively good health, opportunities for older adults to acquire new knowledge, new skills, or learn new languages have flourished.

The target groups will be young adults (< 25y), middle-age adults (40y to 50y), and older adults (> 65y). The middle-age group is critical because it will enable us not only to draw a more accurate trajectory of word learning mechanisms, but also to establish whether compensation based on context and long-term representations begins to operate earlier than traditionally assumed. The learning mechanisms under study will be: (1) Adjacent dependencies: This represents a form of domain-general learning based on implicitly computing statistical regularities in the speech input. We expect this type of learning to be comparatively robust over time. (2) Non-adjacent dependencies: This will instantiate a form of word learning that relies on both association and abstraction, a more complex form of learning that could potentially engage processing resources that are in short supply in older adults. (3) Abstract patterns: These experiments will instantiate abstract pattern learning and generalisation to entirely new materials, unlike adjacent dependencies which require no generalisation to new materials and non-adjacent dependencies which require only partial generalisation to new materials. (4) Rule-based abstraction (first-order logic): This will be similar to the previous set of experiments, except that the abstract patterns defining the acceptable words of the language will be regulated by a grammar containing logical operators (equivalent to if, then, else). This is the most language-specific form of learning of the four sets. Its resilience to aging is largely unknown.

The above learning mechanisms will be compared to their matched explicit-learning counterpart. As a whole, this study will highlight the dynamics and plasticity of language learning over the lifespan and, in doing so, will contribute to our theoretical understanding of language processing, language learning, and cognitive aging.

The research is fundamental science and its primary impact will be scientific. However, the advances in theory and methodology will benefit researchers and practitioners in non-academic settings such as clinical practice, educators, and others with an interest in improving quality of life in older adults. The postdoctoral research fellow's and research assistant's careers will also benefit from the project.

Owing to today's increased life expectancy and the expectation that many of those additional years will be spent in relatively good health, opportunities for older adults to acquire new knowledge, new skills, or learn new languages have flourished (e.g., The University of the Third Age, www.u3a.org.uk). Therefore, our research has the potential to contribute to widening participation in higher education through groups like, e.g., the University of York Centre for Lifelong Learning (http://www.york.ac.uk/lifelonglearning/).

Maintaining the skills that support language learning in old age is crucial not only for second-language learning, but also for reducing older adults' communicative isolation and a sense of losing touch with their own native language, especially with words and expressions pertaining to new technologies such as the Internet and wireless communication. Thus, our research will address fundamental questions such as: How can we keep word learning effective in old age? Can age-related language deficiencies be managed or even attenuated through compensatory mechanisms?

Answers to these questions may facilitate clinical assessment of age-related language declines associated with fronto-temporal dementia and Alzheimer's disease, and especially help identify language-learning skills that might have been spared by the disease (e.g., implicit word learning). Establishing the extent to which reliance on lexical context and long-term memory can compensate for learning difficulties could also inform intervention practice and rehabilitation.

Our work should also be of interest to second-language teachers focusing on teaching foreign languages to mature students. Our data will provide valuable evidence on how to improve older learners' experience of language learning, especially when sensory decline is observed. In that context, the PI's active involvement in the FP7 Marie Curie Initial Training Network INSPIRE (INvestigating Speech Processing in Realistic Environments) will serve as a platform for liaising with the industrial and clinical partners of the network on how to best integrate language learning in the elderly with speech perception and hearing intervention (e.g., Otikon, Phonak, Cochlear, Royal National Throat, Nose and Ear Hospital, Radboud Medical Hospital Center).

On a broader level, we expect that this research will be of relevance to policy makers and the general public. The steady increase in the pensionable age means that adults in the UK are now expected to remain active in the workforce for longer than previous generations. This coincides with a rapid change in the labour market, which demands greater flexibility from employees, and in which a "job for life" is no longer a reality. The implication is that there is increasing pressure for middle-aged adults to re-train and learn new skills. Thus, understanding how the mechanisms that underpin learning and memory change throughout life is essential if we are to support efficient and effective learning in an aging population.