Pioneering a New Method for Investigating the Neural Correlates of Ageing Effects during Natural Reading

Reading is vital for people to function effectively in modern societies. Furthermore, good reading abilities are important for social inclusion and often essential for individuals to work productively, access educational opportunities and acquire new skills. However, numerous studies show that, compared to young adults (aged 18-30 years), older adults (aged 65+ years) experience considerable difficulty reading even when their visual and mental abilities appear normal. Surprisingly little is known about the underlying cause of this age-related reading difficulty or how it might be combated. However, this issue is likely to be increasingly socially important as the proportion of older people in society increase due to population ageing, as well as the likelihood that they will have extended working lives, often in jobs requiring good reading abilities. Scientific investigations of ageing effects on reading are therefore very important.

When we read, our eyes move in a series of high-velocity jumps (saccades) separated by brief pauses (fixations) lasting about a quarter of a second. Readers visually and linguistically process a small portion of text during each fixation, before making a saccade to inspect a new portion. Quantitative measures of these eye movements have been the preferred way to study natural reading, and led to the development of detailed theoretical models of the mental processes that govern this behaviour, including how these might change with age. However, a major limitation of this approach is that eye movements are not directly informative about underlying brain processes, although such knowledge is essential if we are to more fully understand the fundamental mechanisms responsible for ageing effects on reading behaviour.

Our project addresses this issue by pioneering a new method that permits the examination of brain processes in real-time during natural reading. This is achieved by simultaneously recording eye movements using a high-precision eye-tracker and electroencephalographic (EEG) measures of brain activity from electrodes placed on the scalp. We then synchronise these signals so that the EEG record is time-locked to individual fixations on specific words in sentences, thereby allowing us to quantify patterns of brain activity that take place as these words are processed visually. Once averaged (over trials in an experiment), the resulting EEG recording (the fixation-related brain potential, or FRP) exhibits a stereotypical waveform with components (peaks and troughs) that are selectively sensitive to factors that influence a word's recognition.

The co-registration method is difficult to implement. Our first objective, therefore, is to demonstrate the viability of using this method with older adult participants. We propose then to conduct three experiments to establish the utility of this new method for revealing age differences in word recognition during natural reading. To do this, we will assess ageing effects on two key factors that affect word recognition during reading. The first is the frequency of a word's written usage (and so its familiarity to readers), and the second is the predictability of a word from its prior sentence context. Theoretical accounts of ageing effects predict larger effects of both word frequency and word predictability for older than young adults, due to slower lexical processing and greater reliance on context in older age. It will be important, therefore, to establish if our new method can detect age differences in the influence of these factors on brain processes during reading.

There is a significant degree of risk to this project. But if we are successful, the approach we are pioneering is likely to produce a paradigm shift in psychological research on ageing effects on visual cognition (including reading) by providing the tools to develop new theories and obtain new evidence about brain processes that underlie socially-important everyday functions.

In common with other advanced societies, the UK is undergoing a demographic shift in which the age structure of the population is changing so that the proportion of over 65 year-olds will increase from one-in-six today to about one-in-four by 2050. This demographic change will have implications for the working lives of older people and their need to access lifelong learning to ensure they have the skills required to work until much later in life. It is also likely to be of increasing social concern that older people often experience age-associated sensory and cognitive declines that may limit their capacity to work productively, access educational opportunities or acquire new skills.

An important focus of our research to date has been on the effects of these age-associated declines on the reading abilities of older people. Good reading abilities are vital for social inclusion and for individuals to engage in work or benefit from education or training. There is now considerable evidence that older people experience much greater reading difficulty compared to young adults, even when their visual and cognitive abilities appear relatively normal. Scientific research is therefore needed to investigate these age differences in reading ability more closely. The present proposal addresses this issue by introducing a new method for investigating ageing effects on brain processes that underpin the recognition of words during natural reading. Research using this method (including experiments we will conduct during the project) are likely to provide important new knowledge about the mechanisms underlying age-associated reading difficulty. We believe such findings will be of considerable interest and value to a broad range of users, including researchers, organisations concerned with the quality of life of older people, designers of digital technology for older adult users, educationalists and policymakers.

Our reasons for expecting this general interest stem from the very positive interactions we have had from user groups during previous projects investigating ageing effects on reading. Some of these projects were supported by the Ulverscroft Foundation, which is a charitable foundation allied to a publisher of large-print books that provides support for the visually impaired and research into visual and reading impairments. During these projects, we had highly positive interactions with its board of trustees, which helped us to shape our research and engage with potential users. We propose to use this relationship to develop links with a broader network of users in the present project.

As part of our impact plan, we will meet with the board of trustees during the first 6 months of the project to share our plans and obtain guidance on engaging other users. Based on this interaction, we will organise knowledge exchange seminars at the middle and towards the end of the project, to which we will invite the trustees and members of other user groups. We will use the seminars to report on our progress and discuss the potential impact of our work. Towards the end of the project, we will also host a larger-scale workshop to present research findings and raise awareness of ageing effects on visual cognition to a broad range of academics, non-academic users and members of the public.

As a further part of our impact plan, we will also engage in outreach activities with community groups that include older adult members (e.g., The Women's Institute, University for the Third Age), and showcase our work to the public as part of the annual Brain Awareness Week hosted by the University of Leicester in collaboration with the DANA Foundation. Finally, we will develop a website that documents our research, provides protocols for working with older adults, and outlines implications of ageing research for digital technology design, lifelong-learning and policymaking, to ensure we continue to achieve impact beyond the end of the project.