According to the Affective Expectation Model (Wilson, Lisle, Kraft, & Wetzel, 1989), affect is formed with reference to a prior expectation. The model predicts that people's affective reactions to a stimulus are generally assimilated to a prior expectation, except in cases when a discrepancy between the affective expectation and the actual stimulus information exists and is noticed. In such cases, affective reactions are expected to be contrasted away from affective expectations. In the present study, both the assimilation and contrast predictions were tested using the unitization paradigm (Newtson, 1973). We predicted that observers who unitized a not-so-funny film clip at a gross level (thereby extracting a relatively small amount of stimulus information) would assimilate their affective reactions to a prior positive expectation, whereas those who unitized the film clip at a fine level (thereby extracting a relatively large amount of stimulus information) would contrast their affective reactions with the positive expectation. The results supported these predictions, thereby providing the first evidence that affective expectations can produce both assimilation and contrast effects in affective experience, (C) 1999 Academic Press.