Rats were shifted from 32% sucrose solution in one apparatus to a 4% sucrose solution in a different apparatus, and the performance of these animals was compared to rats that received the 4% solution in both situations. Transsituational negative contrast effects were found in both consummatory and instrumental measures of behavior and, in addition, these contrast effects were found to have some elements in common with both successive and simultaneous contrast effects, but were identical to neither.The performance of an animal shifted from a large to a small reward generally suffers in comparison to animals that have had no prior experience with the large reward. This decrement in performance, termed a negative contrast effect, has been found in a wide variety of experimental situations and with a variety of rewards. For example, contrast has been obtained in runways with shifts in amount of food (e.g., Crespi, 1942, DiLollo & Beez, 1966, in complex mazes with shifts to qualititatively different foods (e.g., Elliott, 1928), in free-operant paradigms with shifts in schedule of reinforcement (e.g., Reynolds & Limpo, 1968), and in simple consummatory response situations in" which the shift has been to a lower concentration of sucrose solution (e.g., Flaherty, Capobianco, & Hamilton, 1973;Vogel, Mikulka, & Spear, 1968).The occurrence of a contrast effect implies that the animal is, in some sense, comparing the new reward with the old, and the outcome of this comparison influences the animal's behavior. One question of interest that arises concerning contrast effects relates to the conditions under which this comparison will be made. Specifically, will a contrast effect occur if a shift in experimental situation is made concurrently with a shift in reward, or will reward comparisons be restricted to a given stimulus environment? Premack (l969) attempted to investigate this problem by comparing the performance of rats repeatedly shifted from a situation in which running in a wheel was reinforced by the opportunity to drink milk on a mult VI, VI schedule to a situation in which barpressing on an FR schedule was reinforced with milk. In two of the three rats tested, Premack found evidence that decreases in reinforcement frequency in the running wheel led to increased rates of responding on the FR schedule. In other words, 2 of the 3 animals showed a behavioral contrast effect that was transsituational. In the present experiment, we investigated the influence of stimulus context on reward contrast by varying reward quality (shifting rats from a high-to a low-eoncentrationsucrose solution)This research was supported by a grant from the Rutgers research council and by Grant MH-24612 from the National Institute of Mental Health. Portions of these data were presented at the 1975 meetings of the Eastern Psychological Association.Reprint requests should be sent to Charles Flaherty, Psychology Department, Busch Campus, Rutgers University, New Brunswick, New Jersey 08903.
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