Degree Name

Doctor of Philosophy (PhD)


Department of Psychology - Faculty of Health & Behavioural Sciences


The current thesis examined the effect that phonological similarity has on short-term memory (STM) performance. Across nine experiments, the predictions that two classes of STM models (non-linguistic and psycholinguisitic) generate for the effect that phonological similarity has on the recall of item information and memory for an items position in a list were tested. In the current thesis, phonological similarity was operationally defined in a number of different ways. For instance, lists of consonant-vowel-consonant (CVC) words and nonwords, rhymed (shared VC component), shared the initial consonant and vowel (CV_component) or shared the two consonants (C_C component). Performance across these conditions was compared to when the stimulus lists were either phonemically dissimilar (ie used as a baseline measure of performance or phonemically similar (ie, each stimulus in each list had at least two phonemes in common with at least one other stimulus in the same list). Regardless of whether the experimental stimuli were words or nonwords, when performance was measured using the item recall criterion (scored as correct if a participant recalled an item that was presented in a list, regardless of position), an item recall advantage was observed for rhyming lists of stimuli. Non-linguistic STM models suggest that an item recall advantage should be observed whenever the size of the secondary memory search set can be limited to a smaller number of items (eg all items that rhyme). In contrast, psycholinguistic models of STM assume that this item recall advantage derives from sub-syllabic structures that aid the recall of item information. In terms of the effect that phonemic similarity has on order memory, the findings from the current thesis are inconsistent with the predictions generated from non-linguistic models of STM that are based on the distinctiveness assumption - the idea that as similarity increases order memory should decrease. Rather the findings are consistent with psycholinguistic models of STM that assume that the effect that phonemic similarity has on order memory is a consequence of linguistic constraints, such as sonority, that operate at the sub-syllabic as compared to lexical level. Based on the current research findings, modifications to existing STM models have been proposed.

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