Learning and Motivation 31, 153–179 (2000) doi:10.1006/lmot.1999.1048, available online at http://www.idealibrary.com on Can Orally Consumed Calories Condition Preferences for Relatively Unacceptable Tastes? Catherine A. Forestell and Vincent M. LoLordo Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada A reverse-order differential conditioning procedure adapted from Boakes and Lu- bart (1988) was employed in an attempt to condition preferences to relatively unac- ceptable tastes in rats. Rats received 10 ml of a calorific reinforcer, which after a short delay was followed by one taste cue, either citric acid or sucrose octaacetate (both were mixed in water), and 10 ml of water followed by the other taste cue. During subsequent two-bottle tests, these animals failed to show a preference for the taste that had been paired with the calorific reinforcer relative to the taste that had been paired with water. When the same reverse-order procedure was employed using taste cues which were mixed in saccharin rather than water, rats acquired a significant preference for the CS+ mixture regardless of whether they were water restricted or not. These results suggest that without the presence of saccharin in the CS solutions, rats do not acquire conditioned preferences for relatively unacceptable tastes.  2000 Academic Press Animals often rely on previous experience when determining whether to accept or reject potential food items. It is well documented that when a flavor stimulus is paired with gastric malaise in a classical conditioning paradigm, animals will avoid consuming that stimulus upon subsequent presentation (e.g., Garcia, Kimeldorf, & Koelling, 1955). Classical conditioning has also been used to enhance the acceptability or preference for flavors (for reviews see Sclafani, 1991, 1995). Generally, this is accomplished by pairing a flavor with a source of calories. As a result of this association, the absolute con- sumption (acceptance) of the flavor increases upon subsequent presentation (Drucker, Ackroff, & Sclafani, 1993). Moreover, the preference for the flavor is increased relative to another concurrently presented solution (Holman, 1975; Mehiel & Bolles, 1984; Sclafani & Nissenbaum, 1988). The purpose of the present experiment was to determine whether orally consumed calories can be used to condition a preference for a relatively unacceptable taste. This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. Correspondence can be addressed to Catherine A. Forestell, Department of Psychology, Dalhousie University, Halifax, NS, Canada, B3H 4J1. 153 0023-9690/00 $35.00 Copyright  2000 by Academic Press All rights of reproduction in any form reserved.