Sensitivity to Meaningful Morphological Information Acquired through Reading Experience

The majority of words in English and in other languages are built by combining smaller units of meaning called morphemes (e.g. clean+ly, un+clean). Understanding how a language's morphology works is vital because it allows us to generalise; for example, we can understand 'misclean' because we know that [mis-] and [clean] function as meaningful elements. Research suggests that morpheme knowledge provides an important heuristic for vocabulary growth, and that this knowledge facilitates rapid reading comprehension in adults.

The aim of this project is to discover how we acquire abstract knowledge of affix morphemes (e.g. -ify, -ly). These units typically do not occur in isolation, so their functions must be inferred through experience with whole words (e.g. purify, falsify, simplify). Recent theories suggest that we learn these units because they provide powerful information about word meaning (e.g. -ify means 'to make [stem]'). However, these theories have been developed largely through laboratory experiments using simple miniature languages. The way that morphemes communicate meaning in real language is far more complex: we do not know what drives learning 'in the wild' or what it is that children are learning.

This project develops two research streams to quantify how children's language experience shapes their morpheme knowledge.

Our first research stream offers an unprecedented attempt to quantify the nature of affix information in children's literature. We will build a large-scale children's text corpus including books suitable for ages 7 to 16, and will develop theoretically-driven metrics that capture the nature of affix information. The development of these metrics will capitalise on new computational techniques that permit us to capture how morphemes contribute to meaning in a richer and more nuanced way than has previously been possible. We will calculate these metrics across the whole corpus but also as text accumulates across material suitable for different age bands. This latter analysis is important because the vocabulary used in books across this age range is likely to change considerably (particularly for longer, morphologically-complex words), and this will influence what children can learn about individual affixes.

Our second research stream then probes how the affix regularities uncovered in the first research stream influence children's morphemic knowledge. We will conduct a large-scale behavioural study that measures affix knowledge in children between the ages of 7 and 16. This work advances the state-of-the-art because it allows us to move beyond questions of whether or not relatively small groups of children show morphological effects. Instead, our prediction is that morpheme knowledge should be a function of (a) an individual child's linguistic experience; and (b) the statistical regularity with which specific affixes contribute to word meaning. Item-based measures will be derived from the corpus analysis; participant-based measures will be derived from a variety of measures of language and literacy.

The immediate outcome of this work will be a new theory of how language experience underpins the acquisition of morphemic knowledge. This new theory will contribute more broadly to our understanding of how language experience shapes language knowledge, and it will stimulate new thinking about why reading might be a particularly important source of language experience. This project will also produce a new children's text corpus and high-dimensional semantic representations built from that corpus. These products will be made available in user-friendly interfaces to the fullest extent possible to facilitate future research.