Using the Perceptual Past to Predict the Perceptual Future Influences the Consciously Perceived Present - A Novel ERP Paradigm  Jürgen Kornmeier , Anne Giersch; Kriti Bhatia; Sven P Heinrich; Ludger Tebartz Van Elst; Ellen Joos; (Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany)   C7

The information available through our senses is noisy, incomplete, and to varying degrees ambiguous. Our perceptual system must construct stable and reliable conscious percepts out of this restricted information. It solves this "perceptual inference problem" (as already described by Helmholtz) by integrating memories from the perceptual past and making predictions about the perceptual future. Using ambiguous figures and a new experimental approach, we studied whether and how generating predictions about the future, which are based on regularities from the past, affects processing of the present. Event-related potentials (ERPs) were measured to investigate whether a highly regular temporal context of either ambiguous or unambiguous stimulus variants differently affects processing of a current stimulus and/or task execution. Further, we tested whether abstract symbolic announcements about the immediate perceptual future can replace the past experience of regularities as a source for making predictions. Both ERP and reaction time varied as a function of stimulus ambiguity in the temporal context of a present stimulus. No such effects were found with symbolic announcements. Our results indicate that predictions about the future automatically alters and particularly slows down processing of the consciously perceived present, even if the predictions are irrelevant for the present percept and task. However, direct experiences of past regularities are necessary for predicting the future, whereas abstract symbolic information about the future is not sufficient.