Finding meaning in novel geometric shapes influences electrophysiological correlates of repetition and dissociates perceptual and conceptual priming.

Repeatedly viewing an object can engender fluency-related implicit memory for perceptual and conceptual attributes, as indexed in tests of perceptual and conceptual priming, respectively. Stimuli with minimal pre-experimental meaning allow direct comparisons between these two types of priming and explorations of whether corresponding neural mechanisms differ. We therefore examined electrophysiological correlates of perceptual and conceptual priming for minimalist geometric shapes (squiggles). Response time measures of conceptual priming were evident for squiggles rated by individual subjects as most meaningful, but not for those rated least meaningful. Conceptual-priming magnitude was proportional across individuals to the amplitude of FN400 brain potentials, but only for meaningful squiggles. Perceptual priming was evident for squiggles irrespective of meaningfulness, and perceptual-priming magnitude was proportional to the amplitude of frontal P170 potentials. These findings therefore show that a single exposure to a novel stimulus can lead to neural processing accompanying conceptual priming that is distinct from that accompanying perceptual priming (FN400 potentials vs. P170 potentials, respectively). Overall, this evidence is also relevant to the current debate over the neural correlates of familiarity-based recognition, and runs counter to the prominent supposition that familiarity can be generically indexed by FN400 potentials.

Voss JL ，Schendan HE ，Paller KA 《-》

Conceptual priming and familiarity: different expressions of memory during recognition testing with distinct neurophysiological correlates.

Voss JL ，Lucas HD ，Paller KA 《-》

Remembering and knowing: electrophysiological distinctions at encoding but not retrieval.

Voss JL ，Paller KA 《-》

Neural correlates of familiarity and conceptual fluency in a recognition test with ancient pictographic characters.

Familiarity and conceptual priming refer to distinct memory expressions and are subtypes of explicit memory and implicit memory, respectively. Given that the neural events that produce conceptual priming may in some cases promote familiarity, distinguishing between neural signals of these two types of memory may further our understanding of recognition memory mechanisms. Although FN400 event-related potentials observed during recognition tests have often been ascribed to familiarity, much evidence suggests that they should instead be ascribed to conceptual fluency. To help resolve this controversy, we studied potentials elicited by unrecognizable ancient Chinese characters. These stimuli were categorized as high or low in meaningfulness based on subjective ratings. Conceptual priming was produced exclusively by repetition of characters high in meaningfulness. During a recognition test in which recollection was discouraged, FN400 old-new effects were observed, and amplitudes of the FN400 potentials varied inversely with familiarity confidence. However, these effects were absent for old items given low meaningfulness ratings. For both high and low meaningfulness, late positive (LPC) potentials were found in old-new comparisons, and LPC amplitudes were greater when higher familiarity confidence was registered during the recognition test. These findings linked familiarity and conceptual fluency with different brain potentials - LPC and FN400, respectively - and provide additional evidence that explicit memory and implicit memory have distinct neural substrates.

Hou M ，Safron A ，Paller KA ，Guo C ... -  《-》

Basic perceptual changes that alter meaning and neural correlates of recognition memory.

Gao C ，Hermiller MS ，Voss JL ，Guo C ... -  《Frontiers in Human Neuroscience》