Mechanisms underpinning semantic priming in spoken word retrieval

PhD ThesisA number of studies have shown that speed and accuracy of word retrieval may be affected by the previous retrieval of a word with similar semantic meaning. This phenomenon is called semantic priming and includes both semantic interference or and facilitation. While there is a clear evidence for the presence of semantic priming, the mechanisms causing this effect are still under debate. Therefore, the goal of this PhD was to provide evidence regarding these mechanisms by systematically evaluating the effect of primes with different semantic relations on the speed and accuracy of spoken word retrieval in healthy subjects and people with aphasia. Five experiments were implemented with healthy participants focusing on the effects in priming of semantic coordination, association and part-whole relations on spoken word retrieval with zero or four intervening items between prime and target (lags 0 and 4). Chapter Two reports two experiments using an alternating word reading and picture naming paradigm and Chapter Three, three experiments using a continuous picture naming paradigm. Chapter Four reports two experiments with people with aphasia examining the effects of identity, semantic coordination, association and their interaction on facilitation of picture naming. The results of these two experiments were analysed at both individual subject and group levels. In Chapter Five, these experiments are placed in the context of the previous literature on semantic priming and theories of semantic representation. In this regard, the experimental results are taken to imply that semantic coordination, association, and part-whole relations can be attributed to different types of semantic relations that have different representation and organisation. Further implications of the experiments for our understanding of the mechanisms of lexical access and the nature of lexical representation are discussed