New rather than old? For working memory tasks with abstract patterns the P3 and the single-trial delta response are larger for modified than identical probe stimuli

Abstract

Memory-guided decision making is dynamic and context-dependent, even though many studies describe an enhancement of the P3 for recognized items in memory tasks ("old-new effect"). This study utilized a delay-dependent working memory task during which decision making could be optimized by focusing attention on detected changes instead of recognized similarities. Mean P3 amplitude and delta activity were analyzed from participants who classified probe stimuli as identical or modified. The P3 amplitudes were larger for modified than for identical probes, even when the probe occurred 4,000ms after the primary stimulus. Enhanced single-trial amplitude, trial-by-trial consistency, and frontopariet..