From short-term memory chunks to long-term memory schemas: Learning in the Hebb repetition paradigm

The short-term and long-term memory systems are thought to interact via chunks – long-term memory representations that support maintenance of information. The creation and use of chunks is examined in the Hebb repetition paradigm, where participants repeatedly study and retrieve the same list of serially presented memoranda. This repetition ultimately leads to the creation of a chunk supporting short-term memory performance. Studies conducted to date underscore the inflexible nature of thus created chunks, which always encompass the exact series of memoranda. In contrast to this, the long-term memory system is thought to rely on schemas – flexibly adjusted representations that allow for generalization and transfer of learning. Here we examined whether this difference in the organization of short-term and long-term memory systems is more apparent than real by pursuing a possible role of schemas in a short-term memory task. We adapted the Hebb repetition paradigm so that participants learned and retrieved lists of category exemplars. Crucially, what was repeated here in the Hebb list was the order of categories from which those exemplars were taken, while the memoranda themselves changed from one list presentation to another. We demonstrated that in this task participants were able to derive the schema describing category order in the Hebb list and use it to support short-term memory performance for a novel set of schema-consistent memoranda. We conclude that both the short- and long-term memory systems can be organized around flexibly deployed schemas.