Reduction of Sucrose Reward to Smaller and Nonreward Levels without Contrast Effects

Abstract

Five groups of albino rats were trained in a straight runway for 44 pre-shift trials, 2 trials per day with a 3- to 5-min intertrial interval (ITI). Two of the groups (30-0 and 30-3) received 1 ml of 30% sucrose solution as a reward, two groups (3-0 and 3-3) received an equal volume of 3% sucrose, and one group (0-0) received no reward. During 20 postshift trials, three groups (0-0, 3-0, and 30-0) received no reward, and two groups (3-3 and 30-3) received 3% sucrose. Postshift trials were massed (10/day) with the same ITI as in preshift. The reward shift produced a direct relationship between the amount of preshift reward and resistance to extinction and no evidence of successive negative contrast whether the shift was to smaller or non-reward levels.

Behavior of Maudsley reactive and nonreactive rats (Rattus norvegicus) in three consummatory contrast paradigms.

“…There is some evidence for such an assertion. For example, in spite of the ease with which successive negative contrast is obtained in consummatory behavior, many studies have found that negative contrast does not occur in runway behavior when the concentration of a sucrose solution is decreased, although negative contrast does occur when the volume of sucrose is decreased (e.g., Burns, Lorig, & McCrary, 1986; see Flaherty, 1982, for a review of this literature). In fact, there seems to be no relationship between contrast in consummatory behavior and contrast in runway behavior (Flaherty & Caprio, 1976).…”