Electrophysiological evidence for an independent effect of memory retrieval on referential processing

In this study, we show that the difficulty of re-activating and retrieving the representations of potential referents from memory (retrieval difficulty) influences referential processing, and that this effect is independent of the number of potential referents for a pronoun or the probability of possible referential interpretations (referential coherence). In two experiments, we varied retrieval difficulty by manipulating whether two referential candidates were modified by extra semantic information or not, creating representationally rich (modified) or bare (unmodified) referential candidates, respectively, and we measured event-related brain potentials (ERPs) on following pronouns. We observed a sustained frontal negative shift (the Nref effect) on pronouns following bare, and therefore difficult-to-retrieve, referential candidates relative to those following representationally rich candidates, regardless of the ambiguity of pronouns and the probability of either referential interpretation. Since referential coherence was held constant across the conditions, the results suggest that retrieval difficulty affects referential processing independently of coherence. We discuss the implications for memory-based theories of language processing.