Familiarity And Concept-initiated ERP Research

Familiarity is a kind of explicit memory that involves recognition without the recollection of contextual information. In contrast, conceptual priming is an implicit memory process that can be measured in priming tests as decreased of response time due to repetition of semantic/conceptual information. In recognition memory, there is a controversy about whether FN400potentials indicate conceptual priming, or familiarity, or both conceptual and perceptual processing which contribute to familiarity in recognition. We tested the notion that FN400potentials are neural correlates of conceptual priming. We used novel stimuli known as "squiggles" that vary in their ability to convey conceptual information so that we could obtain perceptual and conceptual fluency. In the first experiment, we confirmed that masked, rapidly presented squiggles were subliminal and not consciously perceived by subjects. In the second experiment, we confirmed that the subset of squiggles that conveyed conceptual information enhanced conceptual fluency when presented subliminally, as indicated by faster response times during a test of conceptual priming. Responses to supraliminal stimuli were faster when subliminally primed by a conceptually meaningful squiggle versus a meaningless squiggle. In the third experiment, we recorded ERPs during a recognition test in which some items were given subliminal conceptual primes. Conceptual priming in recognition memory was indexed by frontal N400ERPs. And subliminal conceptual fluency was indexed by N400ERPs and subliminal perceptual fluency was indexed by80-150ms occipital ERPs. Directly comparison between scalp map of conceptual priming in recognition memory and subliminal conceptual fluency indicates that they have same neural mechanism. And the frontal N400ERPs has no relationship with perceptual fluency. So we can make a conclusion that frontal N400ERPs is the neural correlates of conceptual priming and it is the same as N400ERPs.