Salience and the effects of CS preexposure on aversion conditioning

Rats (n = 84) received preexposure to distilled water or to one of two differently salient flavors, 5.0% casein or 10.0% sucrose, casein being the more salient. Each preexposure group then received aversion conditioning to a 5.0% casein or a 10.0% sucrose CS. Aversion effects were reliably more enduring to casein than to sucrose. Relative to water-preexposed groups, preexposure to casein attenuated aversion effects to the casein CS reliably less than preexposure to sucrose attenuated aversion effects to the sucrose CS. During preexposure, neophobia was reliably greater to casein than to sucrose, suggesting that the demonstration of salience in taste aversion learning may be based on the inherent aversive properties of novelty.