thesis

Phonological Short-Term Memory and New Word Learning: Evidence from Paired-Associate and Hebb Repetition Paradigms

Abstract

This thesis investigated the role of phonological short-term memory (PSTM) in the long-term learning of new phonological word-forms.. Previous studies using the paired-associate paradigm have suggested that the learning of unfamiliar material is mediated by PSTM (e.g. Papagno & Vallar, 1992). The first'aim was. to replicate a!1d extend this previous work. The second aim was to determine whether the Hebb repetition paradigm could provide an alternative method with which to investigate the role of PSTM in new word-form learning. Seven experiments w~re conducted to explore these aims. Experiment 1 obtained phonological similarity effects for words and nonwords in an immediate serial recall task, confirming that. the chosen manipulation of phonological similarity was adequate. Experiments 2 and' 3 . adopted the paired-associate task and replicated Papagno and Vallar' (1992), thus extending their results to English participants and materials. Phonological similarity was shown to selectively disrupt the learning of nonword pairs. In contrast, some evidence was found to suggest that phonological similarity fails to affect the learning' of word pairs. However, Experiment 3 showed that the detrimental effect of phonological similarity was restricted to an intermediate phase of learning. These findings suggest that PSTM mediates the learning of unfamiliar material, although the role of PSTM may change during the course of learning; Experiments 4 and 6 adopted the Hebb repetition task and generated patterns of results consistent with Papagno and Vallar (1992) and Experiments 2 and 3. Phonological similarity disrupted the learning of nonword s~quences, but not the learning of word sequences. These findings suggest that PSTM mediates sequence learning for unfamiliar material, thereby providing initia~ evidence that the Hebb repetition paradigm may be a possible analogue of new word-form learning. The role qf PSTM in nonword sequence learning could not be reliably assessed in Experiments 5 and 7 due to the absence of reliable Hebb Effects. Analyses of between-trial learning and forgetting rates using a Markov model revealed that phonological similarity had a negative impact on forgetting rates for nonwords in both paired-assoCiate and. Hebb repetItion paradigms, suggesting that phonological representations of nonwords are particularly fragile. Finally, it is proposed that the paired-associate paradigm represents a closer analogue of new word-form learning than the Hebb repetition paradigm as it makes use of existing lexical-semantic information

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