The challenges of event cognition: Object representation at the interface of episodic and semantic memory
Language is often used to describe the changes that occur around us – changes in either state (“I cracked the glass…”) or location (“I moved the glass onto the table…”). To fully comprehend such events requires that we represent the ‘before’ and ‘after’ states of any object that undergoes change. But how do we represent these mutually exclusive states of a single object at the same time? I shall summarize a series of fMRI studies which show that these alternative states compete with one another in much the same way as alternative interpretations of an ambiguous word might compete. This interference, or competition, manifests in a part of the brain that has been implicated in resolving competition. Moreover, activity in this area is predicted by the dissimilarity, elsewhere in the brain, between sensorimotor instantiations of the described object’s distinct states. Connectivity analyses show that hippocampus is also implicated in these cases of language/event comprehension, as a function of when episodic or semantic knowledge must be accessed. I shall end with the beginnings of a new account of event representation which does away with the traditional distinction between actions and participants, which maintains instead that object state representations across time are the fundamental representational primitive of event cognition, and which addresses how we instantiate individuated objects (tokens) from semantic memory (about types) on-the-fly. [Prior knowledge of the brain is neither presumed, required, nor advantageous!].