Identifying the locus of repetition priming
People are able to respond more quickly to stimuli following a recent encounter with those same items. This facilitation in processing a stimulus as a function of a prior encounter is known as repetition priming. This thesis contains eleven experiments that attempt to describe the nature of the representations in memory underlying the effect. Changing aspects of the stimuli and task between the initial encounter and the subsequent test encounter allow examination of the kinds of information contained in these representations. The effects on repetition priming of recombining the pairings of simultaneously presented items in a speeded same/different matching task were examined (Experiments 1,2, 3 & 6). Despite priming being insensitive to the pairings of items, subjects were able to recognise this information (Experiment 4), revealing an item-specific locus for the priming effect and a dissociation from explicit memory. Priming was shown to be based on domain- specific and not conceptual information (Experiment 5). Experiments 7 and 8 examined the role of repeating the decision and response to stimuli in producing repetition priming. Results suggested that any such role reflects subjects' use of explicit memory as a basis for responding in the task, rather than reflecting automatic priming effects. Manipulating the semantic interpretation demanded of a homograph between training and test did not affect repetition priming (Experiment 9). The independent representation of simultaneously presented stimuli did not necessarily depend upon the activation of pre-existing representations or connections (Experiment 10). Experiment 11 revealed a necessary role for the identification of stimuli in producing repetition priming. The results of these eleven experiments pose problems for accounts of repetition priming based on the retrieval of processing episodes, or the reinstatement of processing demands. The results are consistent with a perceptual locus of the priming effect, based on representations of structure and form employed in the identification of individual stimuli.