Episodic action memory for real objects: an ERP investigation with perform, watch, and imagine action encoding tasks versus a non-action encoding task.

Cognitive research shows that people typically remember actions they perform better than those that they only watch or imagine doing, but also at times misremember doing actions they merely imagined or planned to do (source memory errors). Neural research suggests some overlap between brain regions engaged during action production, motor imagery, and action observation. The present study evaluates the similarities/differences in brain activity during the retrieval of various types of action and nonaction memories. Participants study real objects in one of four encoding conditions: performing an action, watching the experimenter perform an action, or imagining an action with an object, or a nonmotoric task of estimating an object's cost. At test, participants view color photos of the objects, and make source memory judgments about the initial encoding episodes. Event-related potentials (ERPs) during test reveal (1) content-specific brain activity depending on the nature of the encoding task, and (2) a hand tag, i.e., sensitivity to the hand with which an object had been manipulated at study. At fronto-central sites, ERPs are similar for the three action-retrieval conditions, which are distinct from those to the cost-encoded objects. At occipital sites ERPs distinguished objects from encoding conditions with visual motion (Perform and Watch) from those without visual motion (Imagine and Cost). Results thus suggest some degree of recapitulation of encoding brain activity during retrieval of memories with qualitatively distinct attributes.