Hedonic evaluations and emotional reactions to experiences depend not only upon the conditions being experienced, but also upon the sequences in which conditions are experienced. The authors propose a comparison-induced distortion (CID) model of sequence effects on evaluation in which to-be-evaluated exemplars are verbally compared (Choplin & Hummel, 2002; Choplin, 2007) to the most similar, recent exemplars. Predictions of this model were tested and pit against Helson’s (1964) adaptation-level theory, Parducci’s (1995) range-frequency theory, and Haubensak’s (1992) consistency model using a paradigm in which sequences periodically improved (i.e., improved for n trials, returned to the original state on a single trial, and improved for n trials again) or periodically deteriorated by small or large amounts. The results were consistent with the predictions of the proposed CID model of sequence effects and inconsistent with adaptation-level theory, range-frequency theory, and the consistency model.