The relationship between lexical and non-lexical processes in spelling

Research into children's spelling difficulties has generally focussed on the kind of errors children make, categorising them as 'phonetic' or 'non-phonetic'. These errors are then interpreted within the framework of the 'dual-route' model of spelling. Although this model can account for phonetic errors, the explanation of non-phonetic errors is inadequate. The first half of this thesis investigates the hypothesis that children use non-phonetic phoneme-grapheme mappings to produce non-phonetic spellings. In order to examine these mappings, three studies were carried out to look at children's spelling of nonwords. The first compares the spelling of vowel phonemes in nonwords and real words; the second compares the spelling of vowel phonemes by children with and without spelling difficulties and the third shows how a corpus of nonword spellings can be used to identify problematic phonemegrapheme mappings.In the second half of the thesis, it is suggested that nonwords are not simply spelt using phoneme-grapheme mappings, but that lexical information in the form of morphemes may also be used. Three experiments are described. The first is a phoneme-classification task used to test for the activation of morphemes in the lexicon; in the second and third experiments (carried out on adults and children respectively) nonwords are presented in priming and non-priming contexts to test for the effect of higher level information on the use of morphemes in nonword spelling. The results suggest that not only can morphemes be used in spelling nonwords, but their use can be influenced by the context in which the nonword is presented. It is proposed that the dual-route model should be modified in order to allow for interaction between the lexical and non-lexical routes in nonword spelling, and to allow for the influence of syntactic information on this interaction