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The objective of this thesis is to explore the effect of phrase frequency, word frequency and phonetic complexity (and their interactions) on production fluency in both children and adults. We explore firstly whether the previous findings for independent effects of phrase frequency, word frequency and word complexity on phrase production hold when using phrases that are simultaneously manipulated for all three factors, and secondly how the effects of these properties interact. In particular we aim to explore whether children's phonological learning, like that of adults, involves phonological/motor chunking. This refers to the idea that frequent sequences are represented in phonological working memory as a single unit which can be accessed directly, rather than having to be formed on the fly during production. Therefore, words that are difficult to say when first encountered become easier to articulate due to practice. An interaction between phrase/word frequency and complexity, where complex items are produced more fluently when they are also more frequent, would indicate that phonological/motor chunking is taking place. We also test the secondary prediction that phrase and word frequency will affect (promote or suppress) each other's effect on accuracy. In chapter 3 and 4 we asked children to repeat phrases manipulated for phrase frequency, word frequency and complexity, while chapter 5 uses the same stimuli in adults. We found that, overall, children do use phonological/motor chunking, but only for phrases where they have robust conceptual and phonological knowledge. Furthermore, we found that this effect was driven solely by word frequency in our stimuli - there was no effect of phrase frequency on production in children. Using the same stimuli, we found that adults also showed evidence of phonological/motor chunking for words which were high in frequency, although we found evidence of competition between word frequency and phrase frequency effects that was not seen in the children. Finally, Chapter 6 reports on 2 experiments which use a training session to manipulate non-word sequences for phrase frequency and word frequency. Again, we found that word frequency drives phonological/motor chunking during production. The results from these experiments suggest that young children and adults do undergo phonological/motor chunking. However, importantly, this effect is driven by word frequency - the phrase frequency effects seen elsewhere in the literature must be attributed to other mechanisms (e.g. long term memory associations between the constituent lemmas contained in high frequency phrases).

Perfectionism is a transdiagnostic process associated with a variety of clinical disorders. Although perfectionism has been postulated as being involved in Body Dysmorphic Disorder (BDD), it is unclear whether this association is supported by empirical data and no previous systematic review has attempted to synthesis findings in this field. The aim of the current review was therefore to consolidate published literature that has explored the relationship between perfectionism and BDD. Given the limited literature on BDD patients, this review included studies of the association between perfectionism and appearance-related concerns in analogue samples, unselected samples, and other clinical groups. However, studies that exclusively focussed on body weight/shape concerns pertaining to eating disorders were excluded. Three electronic databases were searched: PsychINFO, PubMed, and Web of Science, returning a total of 1,047 articles, where 41 published articles met the inclusion criteria, utilising 44 independent samples. Only two studies included clinical samples of patients with BDD. The outcome measures used to assess perfectionism and appearance-related concerns were diverse. Nevertheless, 90% of cross-sectional studies reported significant associations between perfectionism and appearance-related concerns. Therefore, in the context of largely cross-sectional data, perfectionism does appear to be reliably associated with appearance-related concerns. The review also demonstrated that Concern over Mistakes (CoM), Doubts about Actions (DaA), Socially-Prescribed Perfectionism (SPP), and maladaptive dimensions of perfectionism were the most consistently related to appearance-related outcomes. These findings need to be considered alongside their limitations. In particular, the vast majority of studies were conducted in unselected student samples, and so it remains unclear whether these findings generalise to patients diagnosed with BDD. Notwithstanding the limitations, the current review highlights the potential role of perfectionism in BDD and the need for further research in this field.