Investigation of the devaluation interpretation of anticipatory negative contrast.

Rats suppress intake of an acceptable substance (e.g., 0.15% saccharin) when it is followed by a preferred substance (e.g., 32% sucrose) in once per day pairings. The role of a learned devaluation of the initial solution in suppressed intake (anticipatory negative contrast) was investigated. The findings included the following: (a) Flavors or odors as within-subject cues precluded the occurrence of anticipatory contrast, conditioning flavor and odor preferences instead, which appeared to antagonize suppressed intake. (b) Anticipatory contrast was obtained when within-subject context cues, temporal alternation cues, or drinking-spout cues were used. (c) Preference tests conducted with the spout cues showed that devaluation of the initial substance was not necessary for the occurrence of negative anticipatory contrast.