The different effects of concept definition and interactive imagery encoding on associative recognition for word and picture stimuli

Traditional view holds that associative recognition require recollection while familiarity can't support associative recognition. However, recent research indicate that familiarity can also contribute to associative recognition when the stimuli are unitized in encoding. Here, we investigated the electrophysiological correlates of retrieval of word and picture stimuli in three encoding conditions. Semantically unrelated word pairs or picture pairs were encoded in concept definition, interactive imagery, and item comparison conditions, separately. In test, the participants were required to discriminate between old pairs that appeared in the same pairing as in study, rearranged pairs that appeared in different pairings in study, or completely new pairs. The behavioral results revealed that higher associative recognition was observed in interactive imagery condition than in concept definition condition, with item comparison condition eliciting the worst recognition, regardless of word or picture stimuli. ERP results of word stimuli revealed that the FN400 old/new effect was solely elicited in concept definition and interactive imagery conditions, but not in item comparison condition. However, ERP results of picture stimuli revealed that the late FN400 old/new effect was observed in three encoding conditions and that larger magnitude of old/new effect was elicited in item comparison condition than in interactive imagery condition. There may be different neural mechanisms of unitization on associative recognition for word and picture stimuli. These findings suggested that the pattern of engagement of familiarity during successful retrieval was dependent on the stimulating properties and the encoding conditions. We will discuss the possibility that top down unitization which manipulates two unrelated stimuli through instructions may lead to the engagement of specific forms of familiarity-association familiarity and item familiarity.