Expectations alter recognition and event-related potentials (ERPs).

Two studies investigated the effect of recognition expectancies (Experiment 1) and decision criterion (Experiment 2) on event-related potentials (ERPs). Participants in both experiments studied meaningless pictures of abstract art and then completed three recognition memory tests with equal proportions of old and new items. To manipulate expectancies (Experiment 1), participants were told to expect equal numbers of old and new items (standard expectancy), more old items (old expectancy), or more new items (new expectancy). The meaningless stimuli did not elicit recognition ERPs under standard testing expectancies, whereas the same stimuli elicited old/new ERP effects in the FN400 and LPC time windows when participants expected more old items. Decision criterion manipulations (Experiment 2) produced different ERP patterns indicating that expectancies alter the decision criterion and produce unique effects on recognition. Collectively, these findings support theory that describes familiarity as an experience that arises from assessing the processing fluency relative to a set of expectations (Whittlesea & Williams, 2001a, 2001b).