Marc Howard (Boston U.) will give the next Cognitive Bag Lunch presentation at 12pm in Tobin 521B Weds. April 12 at noon. Title and abstract below – all are welcome!

Title: Retrieval of temporal context in the brain is associated with high confidence recognition responses

Abstract: Over the last several decades, models of human episodic memory tasks have bifurcated into models of recall and models of item recognition. Many models of recall have relied heavily on recovery of a gradually-changing state of temporal context. This putative mechanism is sufficient to account for the contiguity effect in recall tasks. In contrast, process models of recognition have focused on accessing traces and matching features. We review recent results from neurobiological data demonstrating that the ensemble response in the brain changes across a wide range of time scales from seconds up to at least several days. We present unpublished results from a study using single unit recordings from an item recognition experiment. Human epilepsy patients studied a list of pictures. The single-unit response changed gradually across stimulus presentations, as predicted by models of temporal context. When an old item was presented as a probe and that probe received a highest confidence response, the neural ensemble “jumped back in time”, recovering the prior state of temporal context. When an old probe did not receive a highest confidence response, the effect was not observed, and in fact showed a weak anti-contiguity effect. We review several unpublished behavioral results and discuss a research strategy for constructing unified models of episodic memory performance that include both recall and recognition results.