THE COVERT INTERPLAY BETWEEN PERCEPTION AND MEMORY - EVENT-RELATED POTENTIAL EVIDENCE

Neurocognitive models of visual object identification have focussed on processes at the moment of identification, when perceivers can actual ly name what they see. Less well known is the timecourse of processes preceding and leading to actual identification. To track neuromental p rocesses involved in visual identification, behavioral measures and ev ent -related potentials (ERPs) were recorded in two experiments prior to, during and after the identification of fragmented objects, half of which had been shown in their complete versions in a previous study p hase. Each object was revealed in a sequence of frames wherein the obj ect was represented by an increasingly less and less fragmented image up to the complete version. A shift in ERPs, around 300 Ins and beyond , from negativity to positivity, marked the transition from non-identi fication to identification. However, while for new stimuli such a shif t appeared abruptly from non-identification to identification, for rec ently-studied objects a late positive wave emerged in response to unid entified fragments at a level just prior to overt identification. Thus , ERPs reflected covert processes associated with a successful match b etween the current visual information and episodic recently-stored mem ory traces, which predicted overt identification. (C) 1998 Elsevier Sc ience Ireland Ltd. All rights reserved.