The role of automatic letter-speech sound integration in reading development and dyslexia

Dyslexia is a learning difficulty that affects reading accuracy and speed. A challenge for psychologists is to find out what causes dyslexia. Currently, the best developed theory is that dyslexia is caused by an underlying impairment is how the sound structure of spoken words is represented in the brain. This is referred to as a phonological deficit. Researchers believe that this leads to problems in children's awareness of the sounds in spoken words and to delays in learning the mappings between letters and spoken sounds that are critical for reading. The research described in this proposal will test a novel theory recently put forward by Blomert (2011), that the key problem in dyslexia is a lack of automatic activation of speech sounds from visual letters. That is, even when children with dyslexia have seemingly learned letter-sound associations they are unable to retrieve or apply their knowledge of these quickly during reading. Blomert (2011) has put this lack of automaticity down to a difficulty in learning to link objects across different senses such as vision and hearing. Such an underlying difficulty could help to explain other difficulties seen in children with dyslexia; for example, that they find it difficult to learn to pair together symbols and nonsense words and to say the names of a list of objects or numbers quickly.

Evidence that the automaticity of activating sounds from letters is related to reading and that it is impaired in children with dyslexia comes from neuroimaging studies carried out with Dutch children. The findings suggest that the development of automaticity occurs over a prolonged period; while typically developing 11-year olds showed evidence of it, 8-year olds and children with dyslexia did not. However, it is not clear whether the lack of automatic letter-sound activation in dyslexic children is the cause of their reading difficulties or a consequence of their reduced reading experience.

There remain a number of issues to be addressed before we can be sure that a persisting lack of automaticity in activating sounds from letters is a cause of dyslexia. We need to better understand the development of automatic letter-sound associations in typically developing children and find out how this relates to the other skills that we know affect learning to read. We then need to establish whether automatic letter-sound activation is a predictor of growth in reading in its own right. Once we have done this we can go on to study automaticity in dyslexic children, being careful to compare them to children who have had a similar amount of reading experience. This is important if we are to establish whether a lack of automatic letter-sound activation is the cause of reading difficulties or a consequence of reading experience.

To address these issues we will carry out three studies. In the first we will find out when automatic letter-sound integration first develops and how it relates to reading and other skills that are important for reading development. The second study will follow a group of young children, looking at how automatic letter-sound integration develops over time and whether it is a predictor of growth in reading. In the third study we will compare dyslexic children to children of a similar reading level on measures of automatic letter-sound integration while looking at electrical brain activity. In this way we will determine whether a lack of automatic integration is a potential cause of dyslexia.

The findings will tell us when children begin to develop automatic associations between letters and sounds, whether these automatic associations are important for reading development and if poor associations are a cause of dyslexia. If the answers to the last two questions are yes, then we will have opened up new ways to identify children at risk for dyslexia and for designing interventions to help them develop better connections between letters and sounds.

Who will benefit?
The findings of this research will have practical applications that will benefit a number of groups in wider society. These include children with reading disorders and their families, teachers and education practitioners, dyslexia charities and education policy makers. If we are to develop effective literacy interventions we need to determine the key factors that contribute to poor reading development and develop measures to identify children who are at risk of failure. Successful intervention will improve the child's quality of life.
How will they benefit?
1. Identification of children at risk of poor automatic letter-sound integration and reading difficulties
If variation in children's ability to learn the associations in the newly developed paired associate learning tasks is related to later variation in automatic letter-sound integration and reading ability then one of the tasks we create could be developed for use as a screening test to be used by practitioners to identify young children at risk of reading difficulties upon school entry. Such a task would assess a child's underlying capacity to form cross-modal associations and retrieve auditory information from visual symbols, thus mimicking the demands of letter-sound learning that are central to the early stages of learning to read. To evaluate the tasks as screeners for later reading disorders an unselected sample of children would need to be recruited at the beginning of their reception year, given the learning task/s at this point and then have their early reading ability assessed approximately 1 year later. In analysing the data the average range of performance would be established on the learning task/s and children identified as either below average (at risk) or average and above (not at risk). Risk status would then be used to predict reading outcome status. The accuracy of a screening test is assessed according to its ability to correctly identify people who are and are not affected according to the criterion.
2. Identification of children with poor automatic letter-sound integration
If automatic letter-sound integration is a key predictor of variation in reading and a proximal cause of reading difficulties then the automatic letter-sound integration tasks could be used to identify older children who have not fully automated LS associations and are experiencing subsequent reading difficulties. It is important to identify underlying cognitive impairments in order to design interventions to remediate them and improve reading progress.
3. Intervention
Assuming that automatic letter-sound integration is a continuous variable and that variations relate to variations in reading, then improving automatic letter-sound integration should improve reading. It would seem logical to propose that practice in retrieving the correct sounds from letters, particularly at speed, should improve automatic letter-sound integration. There have been attempts to train letter naming speed in typically developing children, but the findings are mixed. Fugate (1997) found that letter naming speed could be increased in the short term but De Jong and Vrielink (2004) found no such improvement. In both studies the children were in the first year of school and the training was only for a limited period. It remains to be established whether more extensive or prolonged speeded letter sound training would be effective in improving automatic letter-sound integration or decoding in children who are at risk or have impaired letter-sound integration. Furthermore, it may be more beneficial to think in terms of supplementing current early reading intervention programmes rather than training letter naming in isolation.

Research outcomes will be disseminated to the different user groups in a variety of ways, ensuring that the format and content is appropriate for the audience. Our strategy for user engagement is set out in the Pathways to Impact document.