Feature-specific reaction times reveal a semanticisation of memories over time and with repeated remembering

Abstract

Memories are thought to undergo an episodic-to-semantic transformation in the course of their consolidation. We here tested if repeated recall induces a similar semanticization, and if the resulting qualitative changes in memories can be measured using simple feature-specific reaction time probes. Participants studied associations between verbs and object images, and then repeatedly recalled the objects when cued with the verb, immediately and after a two-day delay. Reaction times during immediate recall demonstrated that conceptual features were accessed faster than perceptual features. Consistent with a semanticization process, this perceptual-conceptual gap significantly increased across the delay. A significantly smaller perceptual-conceptual gap was found in the delayed recall data of a control group who repeatedly studied the verb-object pairings on the first day, instead of actively recalling them. Our findings suggest that wake recall and offline consolidation interact to transform memories over time, strengthening meaningful semantic information over perceptual detail.