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1.
Luís Gonzalo De la Casa Auxiliadora Mena Juán Carlos Ruiz-Salas Esperanza Quintero Mauricio R. Papini 《Learning & behavior》2018,46(1):49-59
Three experiments explored the link between reward shifts and latent inhibition (LI). Using consummatory procedures, rewards were either downshifted from 32% to 4% sucrose (Experiments 1–2), or upshifted from 4% to 32% sucrose (Experiment 3). In both cases, appropriate unshifted controls were also included. LI was implemented in terms of fear conditioning involving a single tone-shock pairing after extensive tone-only preexposure. Nonpreexposed controls were also included. Experiment 1 demonstrated a typical LI effect (i.e., disruption of fear conditioning after preexposure to the tone) in animals previously exposed only to 4% sucrose. However, the LI effect was eliminated by preexposure to a 32%-to-4% sucrose devaluation. Experiment 2 replicated this effect when the LI protocol was administered immediately after the reward devaluation event. However, LI was restored when preexposure was administered after a 60-min retention interval. Finally, Experiment 3 showed that a reward upshift did not affect LI. These results point to a significant role of negative emotion related to reward devaluation in the enhancement of stimulus processing despite extensive nonreinforced preexposure experience. 相似文献
2.
In four experiments, the once daily availability of saccharin (.15%) preceded the availability of sucrose (32% or 2%). Experiment 1 showed that the intake of saccharin was reduced when it preceded 32% sucrose but not when it preceded 2% sucrose, as compared with saccharin-alone conditions. Experiment 2 showed that less saccharin was consumed when the saccharin preceded sucrose by 5 min than when there was a 30-min intersolution interval. Experiment 3 replicated this finding and showed that the presentation of the two solutions through the same or different access holes in the apparatus was not relevant to the result. Experiment 4 showed that there was an inverse relationship between saccharin intake and the length of the intersolution interval in the range of 1 to 30 min. These data were interpreted to indicate that the animals learn the predictive relationship between the saccharin and sucrose solutions and that the intake of the saccharin is reduced by an anticipatory contrast mechanism—a mechanism that may have restricted temporal parameters. 相似文献
3.
Contrast in consummatory behavior occurs readily when a less preferred substance follows a preferred substance. A previous experiment indicated that contrast in consummatory behavior may also develop when a less preferred substance precedes a preferred substance in brief daily exposures. In the present experiment, the same animals sometimes received 0.15% saccharin followed, 15 sec later, by 32% sucrose (.15–32) and sometimes received 0.15% saccharin followed by the same 0.15% saccharin solution (.15-.15). One solution pair was given each day, and the two conditions, .15–32 and .15-.15, occurred in alternation across days. The two different solution conditions were correlated with different cues. Saccharin intake from the first tube was lower when the second tube contained 32% sucrose than when it contained .15% saccharin, both in original discrimination training and following a reversal of the cue-solution pairings. These results support the conclusion that contrast in this situation is based on the anticipation of the impending 32% sucrose each day, rather than on a retrograde comparison with the 32% sucrose received the previous day. These data are considered in terms of Pavlovian conditioning outcomes when the CS is a stimulus with hedonic value. 相似文献
4.
Charles F. Flaherty Patricia S. Grigson Cynthia Coppotelli Colin Mitchell 《Learning & behavior》1996,24(1):68-81
Intake of a 0.15% saccharin solution was suppressed when it was followed by a 32% sucrose solution in brief daily pairings. With equal access durations to the two solutions, intervals of intermediate duration (2 or 3 min) produced a larger contrast than more extreme intervals (1 or 10 min). There was no evidence of inhibition of delay with the 10-min interval (Experiments 1A and 1B). When access times were asymmetrical, longer access time to the first solution reduced contrast, whereas longer access time to the second solution enhanced contrast (Experiment 2). Contrast was greater when the two solutions were presented at consistent and separate spatial locations than when location was changed randomly or when both solutions were presented in sequence at the same location. However, a degree of contrast occurred in all conditions (Experiment 3). Experiment 4, conducted with the solutions in opposite arms of a T-maze, showed that anticipatory approach to the location correlated with the 32% sucrose solution developed prior to lick suppression on the saccharin solution. However, within daily sessions, there was a reliable increase in contrast without correlated changes in anticipatory-approach behavior. Access-time effects were attributed to altered reward values, whereas spatial-separation effects suggest that goal-directed responses contribute to, but do not cause, anticipatory contrast. 相似文献
5.
Reactivity to a reward is affected by prior experience with the different reinforcer values of that reward, a phenomenon known as incentive relativity, which can be studied using the consummatory succesive negative contrast (cSNC) paradigm, in which the performance of animals that receive a 4 % sucrose solution after trials on which they were exposed to 32 % sucrose is compared with that of subjects that always receive the 4 % sucrose solution. The exploration of a novel open field can enhance or block the acquisition of associative and nonassociative memories. The effect of open field on cSNC has not yet been explored. The main result of the present study was that open-field exposure significantly modified the expression of cSNC. Exposure to an open field 1 h but not immediately before the downshift interfered with the expression of cSNC. These animals drank more of the downshifted reward than did controls that were not exposed to the apparatus, and this behavior persisted for up to three recovery trials. This phenomenon was observed even when the animals were given a more protracted preshift phase and when the discrepancy between the preshift and shift incentive values of sucrose were increased. An open field also interfered with incentive downshift when open-field exposure occurred 6 h before the downshift, and repeated exposure to the apparatus did not deteriorate this effect. The present study adds to a growing body of literature that indicates that open-field exploration can interfere with memory formation. 相似文献
6.
In a series of three experiments, rats shifted from a 32% to a 4% sucrose solution, after 10 days’ exposure to the 32% solution, exhibited a negative contrast effect in lick rate. In each experiment, shifted rats that received a novel stimulus (tone) during the postshift period exhibited a higher lick rate (smaller contrast effect) than shifted subjects not receiving the tone. This increase in lick rate resembles Pavlovian disinhibition and is interpreted as supporting an inhibitory view of successive negative contrast effects. Control conditions included in Experiments 2 and 3 favored the disinhibition interpretation of the effect of the tone, as opposed to a rate-dependency hypothesis or to the nonspecific energization of behavior. In Experiments 4–6, the tone was introduced coincident with the occurrence of a simultaneous negative contrast effect. Rather than disinhibition, a decrease in licking occurred. These results were discussed in terms of differences between successive and simultaneous contrast. 相似文献
7.
In a consummatory experiment patterned after previous work with rats and goldfish, successive negative incentive contrast was sought in didelphid marsupials of two species (Lutreolina crassicaudata andDidelphis albiventris). Half of the subjects of each species were trained from the outset with a 32% sucrose solution and shifted occasionally to a 4% sucrose solution; the rest, which served as controls, were trained only with the 4% solution. The positive results obtained (less response to the 4% solution in the shifted subjects than in the controls) fit the hypothesis, based on comparative work with descendants of older vertebrate lines, that the mechanism of successive negative incentive contrast evolved in a common reptilian ancestor of birds and mammals. 相似文献
8.
In three experiments, rats shifted from 32% to 4% sucrose consumed less of the 4% sucrose than did rats that had received only the 4% solution. Experiment 1 showed that this negative contrast effect was not accompanied by a corticosterone elevation on the first day subsequent to the shift. Experiments 2 and 2a showed that corticosterone levels were substantially elevated on the 2nd postshift day and that there was a tendency for degree of elevation in corticosterone to be related to degree of lick suppression. These results are discussed in terms of other data suggesting that anxiolytic drugs and disinhibitory stimuli are more effective in alleviating contrast on the 2nd postshift day than on the 1st postshift day. It is suggested that, in the present paradigm, reaction to stimulus change may be the primary determinant of contrast on the 1st postshift day, but emotional processes related to reward loss and/or conflict develop by the 2nd postshift day. 相似文献
9.
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. 相似文献
10.
Rats shifted from 32% sucrose to 4% sucrose lick less than rats that experience oniy the 4% solution. Previous experiments have found this negative contrast effect to be reduced (“disinhibited”) by the addition of a novel tone in the postshift period. In Experiment 1 of this paper, the negative contrast effect was enhanced when a novel flavor was added to the sucrose solution in the postshift period. In Experiments 2–4, changes in the ambient context, even changes sufficient to produce disruptions in licking, did not alter the degree of negative contrast. Tiese results suggest that (1) rats compare rewards across substantially different contexts, (2) contrast may serve to enhance taste neophobia, and (3) a disinhibitory effect may be confined to the presentation of punctate, nontaste, novel stimuli within a familiar context. 相似文献
11.
Rats were given alternating 1-min access to two tubes containing sucrose solutions that varied in concentraton (32% vs. 2%, 32% vs. 4%, 32% vs. 8%, and 32% vs. 16%). Lick rate for 32% sucrose was higher when the alternative tube contained a lower concentration solution than when both tubes contained 32% (a positive-contrast effect), and lick rate for the lower concentration solution (2%, 4%, 8%, or 16%) was lower when the alternative tube contained 32% than when both tubes contained the lower concentration solution (negative contrast effect). Proportion of licks made for 32% under contrast conditions tended to match the proportion of concentration available from that tube. Regression analysis of the ratio of licks made to the two tubes under contrast conditions as a function of ratio of concentrations available indicated a good fit to a power function with an exponent of 1.13, within the range of those typically found in human magnitude estimation studies of relative sweetness. 相似文献
12.
Philipp J. Kraemer Heather Hoffmann Christopher K. Randall Norman E. Spear 《Learning & behavior》1992,20(3):219-222
This experiment established that for the infant rat, 10 days postpartum, a preference conditioned to an olfactory stimulus (conditioned stimulus) could be substantially-decreased-by subsequently lowering the value of the unconditioned stimulus (heat). This devaluation effect disappeared when a sufficiently long interval elapsed between the devaluation treatment and the test, despite maintained retention of the original conditioned preference over this same interval. This suggests that devaluation in infant rats does not permanently change the animal’s original representation of the unconditioned stimulus, but instead may replace it temporarily with a conflicting representation. 相似文献
13.
Ben A. Williams 《Learning & behavior》2002,30(1):1-20
Behavioral contrast is defined as a change in response rate during a stimulus associated with a constant reinforcement schedule,
in inverse relation to the rates of reinforcement in the surrounding stimulus conditions. Contrast has at least two functionally
separable components: local contrast, which occurs after component transition, and molar contrast. Local contrast contributes
to molar contrast under some conditions, but not generally. Molar contrast is due primarily to anticipatory contrast. However,
anticipatory contrast with respect to response rate has been shown to be inversely related to stimulus preference, which challenges
the widely held view that contrast effects reflect changes in stimulus value owing to the reinforcement context. More recent
data demonstrate that the inverse relation between response rate and preference with respect to anticipatory contrast is due
to Pavlovian contingencies embedded in anticipatory contrast procedures. When those contingencies are weakened, anticipatory
contrast and stimulus preference are positively related, thus reaffirming the view that the reinforcing effectiveness of a
constant schedule is inversely related to the value of the context of reinforcement in which it occurs. The underlying basis
of how the context of reinforcement controls reinforcement value remains uncertain, although clear parallels exist between
contrast and the effects of contingency in both Pavlovian and operant conditioning. 相似文献
14.
Bruce R. Lombardi 《Learning & behavior》1980,8(4):617-620
In two experiments, a successive negative contrast effect in licking was produced by shifting rats from 32% to 4% sucrose solution. Subsequent to the downshift in reward, the rats were tested for licking either a plain 12% sucrose solution or 12% plus a neutral flavor. Licking for the 12% solution was depressed in downshifted rats when a flavor was present, regardless of whether this flavor was novel or had been present in the shift solution. The results were interpreted in terms of an enhancement of neophobia by reward reduction. 相似文献
15.
Hooded Lister rats exhibited less neophobia towards (i.e., drank more of) a novel fluid (3% lemon or 5% sucrose) on a 10-min test if given a 6-min exposure to that fluid 6 h earlier. Presentation of a distractor (1.26% coffee) immediately after preexposure to the test solution enhanced neophobia habituation to lemon (Experiment 1), but disrupted habituation to sucrose (Experiment 3). This bidirectional distractor effect was not due to distractor-induced change in the hedonic value of the preexposed test flavor (Experiment 4). Evidence was obtained (Experiment 5) indicating that the rat perceives lemon to be more similar to coffee than is sucrose. It is suggested that when test flavor and distractor are dissimilar, processing of the distractor denies the preexposed test flavor sufficient processing in STM to allow encoding of information about that flavor in LTM. Consequently, the rat responds to a subsequent presentation of the test flavor as it would to a novel stimulus. When test flavor and distractor are similar, however, the distractor elicits less processing in STM (cf. Wagner, 1976) and is therefore less able to disrupt STM processing of the preexposed test flavor. The resultant loss of neophobia to the test flavor resulting from encoding of information about that flavor in LTM may then be augmented by generalization of attenuated neophobia to the distractor. Consistent with this analysis, coffee was shown to suffer more proactive interference when preceded by lemon than when preceded by sucrose (Experiment 6). 相似文献
16.
In three experiments, the time horizon over which the rat evaluates alternative feeding sources was investigated. The time horizon was measured by the suppression of intake of one incentive (a 0.15% saccharin solution) when a preferred alternative incentive (a 32% sucrose solution) was available but delayed. In Experiment 1, we found a direct function between the amount of saccharin intake and the delay time before access to 32% sucrose. Compared with intake for a saccharin-only control, saccharin intake was suppressed before 4-min and 16-min sucrose delays, but not before a 32-min delay. Because previous work (Flaherty & Checke, 1982) had reported suppression before a delay of nearly 32 min, in the subsequent experiments we examined factors that might account for this difference. In Experiment 2, we found that saccharin intake was suppressed before a 32-min delay interval when saccharin and sucrose solutions were presented in a bright-novel test environment but not when the same solutions were presented in the home cage. In Experiment 3, we found that the time between testing and subsequent postsession feeding could also affect the suppression of saccharin intake. Saccharin intake was suppressed when access to 32% sucrose was delayed by 32 min and the test situation was followed by immediate postsession feeding, but not when postsession feeding was delayed by 90 min. These results thus extend estimates of the rat’s time horizon to at least 32 min, but indicate that the effective time horizon can vary, depending on the test situation. 相似文献
17.
Aitken (1999) argues that, in a simultaneous discrimination, reports of the transfer of value from the positive to the negative stimulus can be more readily explained in terms of an artifact produced by the procedure in which differential inhibition accrues to the negative test stimuli during training, together with stimulus generalization (similarity between the positive and negative stimuli). We argue that (1) there is little evidence for differential inhibition, and it often occurs in the wrong direction; (2) value transfer can be demonstrated when differential value is established to the positive stimuli afterdiscrimination training, when differential inhibition is not likely to be a factor; and (3) on both logical and empirical grounds, stimulus similarity does not provide an adequate account of the transfer of value from the positive to the negative stimulus (i.e., the strongest evidence for value transfer occurs when there is least stimulus similarity). We propose that value transfer occurs whenever there is relatively little experience with the negative stimuli. However, when there is extended experience with the negative stimuli, contrast will be found. 相似文献
18.
Contrast in consummatory behavior was investigated following repeated shifts from 32% to 4% sucrose. In Experiment 1, contrast in licking and in open-field measures of activity occurred following the second and third downshifts. In Experiments 2a and 2b, equivalent contrast effects occurred following the first and second downshifts in sucrose. In Experiment 3, negative contrast remained unabated following nine downshifts in animals shifted between 32% and 4% sucrose on alternate days. Similar results were found for five downshifts in animals shifted every 2 days. In both of these latter conditions, positive contrast occurred over the first few shifts and was then lost as the 32% control group reached asymptote. These data show that repeated negative contrast effects in consummatory behavior are robust and enduring and occur under several different sets of experimental parameters. The results are discussed in terms of reinforcement level and emotional interpretations of contrast effects, and the possibility was suggested that the causal mechanism of contrast changes with repeated shifts. 相似文献
19.
In conditioned suppression discriminations, the Konorski-Lawicka paradigm involves A+ trials, where conditioned stimulus A is followed by shock, and sh → A? trials, where A is preceded by shock Rats easily mastered this A+/sh → A? discrimination, as indicated by suppression of food-reinforced barpressing on A+ trials and acceleration of barpressing on sh → A? trials. A history of A+ conditioning resulted in nearly perfect discrimination performance on the very first day of A+/sh → A ? training, but a history of sh→ A? conditioning retarded development of the discrimination. The basis for the development of the discrimination was discussed in terms of an inferred stimulus (sh′) arising from the aftereffects of shock. 相似文献
20.
In previous studies of anticipatory contrast, identical target components (A and B) preceded either a lower (extinction) or a richer schedule. Higher response rates occurred during the target preceding the lower rate of reinforcement, whereas preference was in favor of the target preceding the richer schedule. In Experiment 1, the response and preference measures were positively related when additional stimuli, with no reinforcement of their own, preceded the target components. The effect of these additional stimuli was presumed to be due to their overshadowing of the Pavlovian association between the target components and their following schedules. Experiment 2 also demonstrated a consistent relation between response rate and preference in a conditioned reinforcement procedure. In the absence of a strong Pavlovian association, anticipatory contrast, like other forms of contrast in free-operant procedures, reflects an increase in the value of the target component with an unchanged reinforcement schedule. 相似文献