Cognitive Brown Bag, 1/31/18, 12:00-1:15, Tobin 521B.
Patrick Sadil (PBS)
Pattern-completion of intra-item associations
Some neurocomputational theories of episodic memory have cast recollection as a pattern-completion process during which information is retrieved. In contrast to the pattern-matchingprocess of familiarity, recollection is thought to be most useful in tasks that require retrieval across episodic-like, arbitrary associations (e.g., retrieval of an item cued by a context). However, it is unclear whether pattern-completion occurs for the retrieval of purely visual, intra-item associations that exist at a lower level of representation in the brain’s processing hierarchy. In this experiment, we asked whether recollection, operationalized as the retrieval of previously studied material that is not provided as part of the cue, can occur for the features of single, everyday objects. Participants studied images of everyday objects. To manipulate the degree to which participants could encode arbitrary associations (e.g., the object with the experimental context) some objects were masked with continuous flash suppression. At test, participants were given a cued-recall test in which a small part of the studied object was presented and the task was to identify the whole object. Immediately after the cued-recall, participants engaged in a target detection go/no-go task where the inverse of the object part (i.e., the entire object save for the part used as a cue) might or might not emerge out of visual noise. The key question was whether the response time distribution was shifted earlier on go trials for objects that were studied under continuous flash suppression (as compared to a not-studied baseline) , in particular when the name of the object was not recalled immediately prior. Participants detected the non-recalled CFS-studied objects appearing from the noise more rapidly, and the speed-up corresponded to a shift in the response time distribution. This suggests that participants had a ‘head-start’ on the go trials, despite an inability to identify the cued object. This head-start suggests that a visual pattern-completion process occurred during cued-recall even when participants only encoded – and so could only retrieve – intra-item associations.