Welcome to the real world: validating fixation-related brain potentials for ecologically valid settings

Exploration of the real world usually expresses itself through a perceptual behaviour that is complex and adaptive -- an interplay between external visual and internal cognitive states. However, up to now, the measurement of electrophysiological correlates of cognitive processes has been limited to situations, in which the experimental setting confined visual exploration to the mere reception of a strict serial order of events. Here we show -- exemplified by the well known old/new effect in the domain of visual word recognition -- that an alternative approach that utilizes brain potentials corresponding to eye fixations during free exploration reveals effects as reliable as conventional event-related brain potentials.