Effects of shifts in sucrose and saccharine concentrations on licking behavior in the rat.

Abstract

To study effects of shifts in concentration of liquid reinforcers on licking behavior 4 experiments were performed. Depressed performance (relative to control groups) accompanied a shift from 32% to 4% sucrose solutions, but not a shift in saccharine concentrations. Various bases for this disparity were investigated, including type of deprivation and levels of deprivation. Depression in licking appears to result from shifts in sucrose concentration, with larger depressions accompanying increased amounts of preshift training, but this phenomenon does not occur following shifts in saccharine concentration.The effects of shifts in incentive magnitude have usually been studied in the instrumental running situation. A study by Collier, Knarr, and Marx (1961) has suggested that the licking response may be more sensitive to incentive effects than is running speed. The present experiments were designed to investigate the effects of shifts in incentive magnitude on the licking response.EXPERIMENT 1 Method Subjects and apparatus. Twenty adult male albino rats of the Sprague-Dawley strain were 60 days old at the start of the experiment. Two identical wire cages (8 X 934 X 7 in.) of the type used to house /Ss were used for experimental training. These cages were not housed in sound-attenuating chambers, although, in each of the other experiments reported here, training and test cages were enclosed in sound-attentuating chambers. Although this was originally viewed as a potentially important consideration, sound attenuation did not noticeably affect the results. By extending their tongues through the wire mesh Ss could lick from the glass drinking tubes mounted on the outside of the cages. A drinkometer was connected between the solution and the cage floor, so that S completed the circuit whenever it licked the tube.Procedure. All /Ss were maintained on a daily deprivation regimen of 10 gm. of powdered Purina chow (plus ad-lib water) given to each S 10-30

The effects of dorsal hippocampal lesions on reinforcement shifts

“…The major research finding was that hippocampal Ss show a rapid and appropriate adjustment to increases in incentive and an undershooting of control levels following a reduction of incentive (a NCE). This result is the standard response pattern seen following reward shifts (Black, 1968;Vogel, Mikulka, & Spear, 1968). These findings are not consistent with the results reported by Murphy and Brown (1970), using a very similar research design.…”

“…However, these Ss do show the typical magnitude of reward effects during the preshift-acquisition phase. In contrast, Murphy and Brown (1970), using a licking response, found rapid behavioral adjustment to a decreased reward, but failed to find any evidence of the well-documented negative contrast effect (NCE; Black, 1968;Vogel, Mikulka, & Spear, 1968)_ Murphy and Brown also found that the same Ss did not display any preference for varying sucrose concentrations in preference tests, but did respond appropriately during the preshift phase.The present experiment was conducted fo examine the effects of dorsal hippocampal lesions on lick rates after reward shifts. The lesions used in this study were considerably more localized than the complete hippocampal aspirations used by Franchina and Brown (I 971) and Murphy and Brown (1970)_ Furthermore, this design used a symmetrical shift paradigm, while Murphy and Brown (I970) only shifted their Ss to lower reward levels.…”

“…However, these Ss do show the typical magnitude of reward effects during the preshift-acquisition phase. In contrast, Murphy and Brown (1970), using a licking response, found rapid behavioral adjustment to a decreased reward, but failed to find any evidence of the well-documented negative contrast effect (NCE; Black, 1968;Vogel, Mikulka, & Spear, 1968)_ Murphy and Brown also found that the same Ss did not display any preference for varying sucrose concentrations in preference tests, but did respond appropriately during the preshift phase.…”

Consummatory Successive Negative Contrast in Mongolian Gerbil (Meriones unguiculatus)

“…a phenomenon that don't fit Thorndike's classic law of effect (Herrnstein, 1970;Thorndike, 1911), which predicts an association between behavior and its consequences. This rupture can be clearly perceived when individuals are exposed to a surprising devaluations in the reward quality or quantity received in response to instrumental (Crespi, 1942) or consummatory behavior (Vogel, Mikulka & Spear, 1968). In a typical SNC experiment, a group of rats receives a 32% sucrose solution in a 5-min-long sessions for 10 days (preshift) and then are presented with a 4% sucrose solution in 5-min-long sessions for 5 days (postshift).…”

Transsituational negative contrast

“…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.…”