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1.
The role of incentive learning in instrumental performance following a shift in the degree of water deprivation was analyzed in three experiments. In Experiments 1A and IB, rats trained to perform an instrumental action reinforced with either sucrose or maltodextrin solutions when in a high-deprivation state were subsequently shifted to a low-deprivation state and tested in extinction. This within-state shift in water deprivation reduced instrumental performance only when the animals had been exposed to the reinforcer in the low-deprivation state prior to instrumental training. In Experiment 2, a concurrent training procedure was used to assess whether the change in the value of the reinforcer brought about by preexposurewas mediated by the contingency between the instrumental action and the reinforcer. Preexposure to the reinforcer under the low-deprivation state produced a selective reduction of the performance of the action upon which it was contingent during training when testing was conducted in extinction following a shift from the high- to the low-deprivation state. These experiments provide evidence that animals have to learn about the incentive value of a reinforcer in a particular motivational state through exposure to the reinforcer in that state. 相似文献
2.
The effect of food deprivation level at the time of initial exposure to a subsequent food reinforcer was investigated in two experiments. In Experiment 1, deprivation at the time of initial exposure influenced the subsequent acquisition and extinction of an instrumental response. In Experiment 2, the residual deprivation effect associated with a reduction in deprivation level occurred only when rats initially experienced the reinforcer at a high, as compared with a low, deprivation level. Results were discussed in terms of the assumption that the limits of incentive generated by a reinforcer are influenced by the deprivation state at the time of first exposure to that reinforcer. 相似文献
3.
Hungry rats were trained to perform two instrumental actions, one for salt- and the other for lemonflavored polycose solution. When they were sated on one of these two outcomes by prefeeding immediately prior to a choice extinction test, the action trained with the prefed solution was performed less than the other action. The subsequent experiments examined the role of incentive learning in this specific satiety-induced outcome revaluation effect. The second experiment demonstrated that the experience of consuming a flavored polycose solution to satiety enabled the state induced by polycose consumption to control the devaluation of the flavored outcome. By contrast, the third study found that, although devaluing the prefed outcome, specific-satiety treatments could induce a relative inflation in the incentive value of other food outcomes. The final two studies demonstrated an increased outcome-devaluation effect in instrumental performance when these devaluation and revaluation effects were combined. Taken together, these studies demonstrate that specific satiety treatments produce changes in outcome value that depend upon incentive learning. 相似文献
4.
The control of goal-directed, instrumental actions by primary motivational states, such as hunger and thirst, is mediated by two processes. The first is engaged by the Pavlovian association between contextual or discriminative stimuli and the outcome or reinforcer presented during instrumental training. Such stimuli exert a motivational influence on instrumental performance that depends upon the relevance of the associated outcome to the current motivational state of the agent. Moreover, the motivational effects of these stimuli operate in the absence of prior experience with the outcome under the relevant motivational state. The second, instrumental, process is mediated by knowledge of the contingency between the action and its outcome and controls the value assigned to this outcome. In contrast to the Pavlovian process, motivational states do not influence the instrumental process directly; rather, the agent has to learn about the value of an outcome in a given motivational state by exposure to it while in that state. This incentive learning is similar in certain respects to the acquisition of “cathexes” envisaged by Tolman (1949a, 1949b). 相似文献
5.
John H. Hull 《Learning & behavior》1977,5(2):207-212
Experiments 1, 2, and 3 showed that food-deprived rats responding for food pellets made significantly more long-duration leverpresses than water-deprived rats responding for water drops. These experiments further showed that this difference in instrumental response topography is long-lived, and depends neither upon idiosyncrasies of the experimental chamber nor upon severity of deprivation conditions. In Experiment 4, food-deprived rats responding for food pellets made significantly more long-duration leverpresses than did either food- or water-deprived rats responding for sucrose solution. Human judges in Experiment 5 were able to correctly identify instrumental leverpress responses by rats as being for food or water based solely on previous viewings of other rats drinking water or eating food pellets. It appears that instrumental response topographies in rats vary depending principally upon the reinforcer received, and that these instrumental response topographies resemble consummatory response topographies. 相似文献
6.
In four experiments, we investigated encoding of the reinforcer in instrumental learning. We contrasted the view that the reinforcer is encoded as a consequence of the response with the position that the expectation of the reinforcer serves as an antecedent stimulus for the response. In all four experiments, a response was followed by one reinforcer in the presence of a stimulus known to elicit an expectation of a different reinforcer. In Experiments 1 and 2, we found that devaluing the consequent reinforcer reduced performance of the response more than did devaluing the expected reinforcer. In Experiment 3, we found no evidence at all for a detrimental effect of devaluing the expected reinforcer. Experiment 4 showed that a stimulus associated with a reinforcer will preferentially promote a response that has the same-consequent reinforcer rather than the same-antecedent reinforcer. These results provide further support for the view that response-reinforcer associations are the crucial product in instrumental learning situations. 相似文献
7.
It has been reported previously that rats prefer a flavor they consumed under high deprivation to a flavor they consumed under low deprivation (Revusky, 1967). Here it was found that this preference occurs only if nutritive solutions are used and the flavors are given preceding and following eating. If flavors are given separately from the daily feeding, rats prefer the flavor given under low deprivation, whether or not a nutritive solution is used (Experiment 3). If flavors are given before and after the daily feeding, rats prefer the flavor they had under high deprivation (before feeding) more if sucrose solutions are used than if saccharin solutions are used and more on a high-deprivation test than on a low-deprivation test (Experiments 1 and 2). It was concluded that the “incentive value” of consumption is not necessarily higher under high deprivation than under low deprivation. The preference for the low-deprivation flavor obtained here may reflect a greater proportional rewarding effect of consumption under low deprivation or may reflect an aversion to the flavor consumed under high deprivation. Perhaps a small taste of flavor under high deprivation initiates responses of digestion that are unsatisfied and thus aversive, and the more so the higher the deprivation level. 相似文献
8.
Urcuioli PJ 《Learning & behavior》2005,33(1):1-21
The role of the reinforcer in instrumental discriminations has often been viewed as that of facilitating associative learning
between a reinforced response and the discriminative stimulus that occasions it. The differential-outcome paradigm introduced
by Trapold (1970), however, has provided compelling evidence that reinforcers are also part of what is learned in discrimination
tasks. Specifically, when the availability of different reinforcing outcomes is signaled by different discriminative stimuli,
the conditioned anticipation of those outcomes can provide another source of stimulus control over responding. This article
reviews how such control develops and how it can be revealed, its impact on behavior, and different possible mechanisms that
could mediate the behavioral effects. The main conclusion is that differential-outcome effects are almost entirely explicable
in terms of the cue properties of outcome expectancies—namely, that conditioned expectancies acquire discriminative control
just like any other discriminative or conditional stimulus in instrumental learning. 相似文献
9.
In two experiments, two groups of rats were trained in a navigation task according to either a continuous or a partial schedule
of reinforcement. In Experiment 1, animals that were given continuous reinforcement extinguished the spatial response of approaching
the goal location more readily than animals given partial reinforcement—a partial reinforcement extinction effect. In Experiment
2, after partially or continuously reinforced training, animals were trained in a new task that made use of the same reinforcer
according to a continuous reinforcement schedule. Animals initially given partial reinforcement performed better in the novel
task than did rats initially given continuous reinforcement. These results replicate, in the spatial domain, well-known partial
reinforcement phenomena typically observed in the context of Pavlovian and instrumental conditioning, suggesting that similar
principles govern spatial and associative learning. The results reported support the notion that salience modulation processes
play a key role in determining partial reinforcement effects. 相似文献
10.
In two experiments, rats received preexposure consisting of six intraperitoneal injections of lithium chloride (LiCl). This
treatment reduced the magnitude of the unconditioned response (UR; suppressed consumption of a novel flavor) evoked by an
additional injection (Experiment 1) or by oral consumption (Experiment 2) of LiCl. In both experiments, preexposure also attenuated
the acquisition of a conditioned aversion with an LiCl injection as the unconditioned stimulus (US) but had no effect on the
aversion produced when the US was oral consumption of LiCl (Experiment 2). These results are consistent with the view that
the reduced ability of the preexposed US to serve as a reinforcer depends on blocking by injection-related cues and is independent
of habituation of the UR recorded in the present study. Possible interpretations of this dissociation are discussed. 相似文献
11.
Two experiments examined the effects of extended training on the development of response-reinforcer associations. Rats were trained by using various food reinforcers to make multiple instrumental responses. Subsequently, those reinforcers were devalued by being paired with a toxin. The presence of response-reinforcer associations was inferred from the decrease in the likelihood of a response following devaluation of its reinforcer. Such response-reinforcer associations are known to contribute to performance after moderate amounts of training. These experiments addressed the question of whether the contribution of those associations remains constant, increases, or decreases with more extended training. Experiment 1 found that even after a response had been extensively trained with one reinforcer, the substitution of a new reinforcer produced new associations between the response and that new reinforcer. After extended training, a response continued to acquire new associations with a reinforcer, as indexed by the impact of a devaluation procedure. Experiment 2 directly compared the contribution of reinforcers used extensively and moderately with the same response. It found that devaluation of the extensively used reinforcer more effectively reduced performance of the response, suggesting that the associations formed with additional training contribute to performance of the response. These experiments indicate that the contribution of response-reinforcer associations does not decrease but, instead, continues to grow throughout the course of extended instrumental training. 相似文献
12.
Andrew R. Delamater 《Learning & behavior》1997,25(4):400-412
In two experiments, the possibility of outcome-selective reinstatement of conditioned responding was examined. Evidence for outcome-selective reinstatement of previously extinguished appetitively conditioned magazine responses by rats was observed in both Pavlovian (Experiment 1) and discriminated instrumental conditioning (Experiment 2) procedures. In both experiments, stimulus-elicited magazine responses occurred more in the presence of a stimulus whose reinforcer was reinstated than they did in the presence of another stimulus whose reinforcer was not reinstated. This effect was observed after both brief and extensive amounts of extinction. Outcome-selective reinstatement of instrumental leverpressing, however, was not observed, although nonselective reinstatement of magazine responding and leverpressing was obtained in Experiment 2. Overall, the data from these studies challenge existing theories of reinstatement, and they provide additional evidence of the importance of outcome-specific processes in the control of learned performance. 相似文献
13.
Ruth M. Colwill 《Learning & behavior》2001,29(2):153-164
The effect of noncontingent outcomes on an instrumental response-outcome (R-O) association was examined in four experiments using transfer tests. In each experiment, rats were first given instrumental discrimination training designed to establish different stimuli as signals (S+s) for different outcomes. Transfer responses were subjected to different treatments across the experiments and then tested with the S+s. In Experiments 1 and 2, two transfer responses were both initially trained with two contingent outcomes. Then, each transfer response was subjected either to the addition of noncontingent presentations of one of those outcomes (Experiment 1) or to the replacement of one of the contingent outcomes with noncontingent presentations of that outcome (Experiment 2). Transfer tests revealed no significant difference in the ability of an S+ to promote performance of a transfer response based on their shared association with either the contingent or the noncontingent outcome. These results suggest that a response reinforced with two outcomes remains equally well associated with both of those outcomes despite prolonged exposure to noncontingent presentations of one of those outcomes. In Experiments 3 and 4, the possibility that the noncontingent schedules of reinforcement used in Experiments 1 and 2 might be capable of establishing an association between a response and its noncontingent outcome was examined. Transfer responses were trained with one contingent outcome and a different noncontingent outcome. Performance of these transfer responses was augmented more by presentations of an S+ trained with the contingent outcome than with the noncontingent outcome. These results confirm previous reports that instrumental responses are sensitive to outcome contingencies in acquisition and that noncontingent outcome presentations do not weaken previously established R-O associations. Several explanations are considered for the failure of subsequent noncontingent presentations of an outcome to reduce the strength of its association with the instrumental response. 相似文献
14.
In three experiments that used appetitive preparations with rats, we examined the effects of reinforcing a compound consisting of two previously reinforced stimuli on subsequent responding to those stimuli. Experiment 1 showed that a Pavlovian conditioned stimulus given this treatment evoked fewer magazine entries when presented alone than did a reinforced stimulus that did not receive the compound treatment. Experiment 2 examined inhibition of delay and generalization decrement accounts for the results of Experiment 1. Experiment 3 extended this finding to an instrumental learning paradigm. 相似文献
15.
Conditioned attention theory (CAT) of latent inhibition (LI) states that parallel learning processes occur during reinforced and nonreinforced stimulus presentation. The present experiments investigated the effects of nonreinforced preexposure of either a compound CS or elements of that compound which differed in salience. Three predictions were advanced: (1) Both the compound and its elements will show an increase in LI as a function of the number of preexposures; (2) the two elements will show different levels of LI, with more LI accruing to the more salient element; (3) overshadowing will occur during compound preexposure. Two experiments, using rats as subjects and a conditioned suppression test, are reported. In Experiment 1, groups received 0, 20, 40, or 80 nonreinforced preexposures to a compound whose elements differed in salience. The results of the subsequent test confirmed predictions 1 and 2. Experiment 2, in which groups were preexposed to either the elements or the compound, provided evidence for an overshadowing effect, confirming prediction 3 from CAT. 相似文献
16.
Hungry rats were trained to press a lever for food pellets prior to an assessment of the effect of a shift in their motivational state on instrumental performance in extinction. The first study replicated the finding that a reduction in the level of food deprivation has no detectable effect on extinction performance unless the animals receive prior experience with the food pellets in the nondeprived state (Balleine, 1992; Balleine & Dickinson, 1994). When tested in the nondeprived state, only animals that were reexposed to the food pellets in this state between training and testing showed a reduction in the level of pressing during the extinction test relative to animals tested in the deprived state. The magnitude of this reexposure effect depended, however, on the amount of instrumental training. Following more extended instrumental training, extinction performance was unaffected by reexposure to the food pellets in the nondeprived state whether or not the animals were food deprived at the time of testing. A second study demonstrated that the resistance to the reexposure treatment engendered by overtraining was due to the animals’ increased experience of the food pellets in the deprived state during training rather than to the more extensive exposure to the instrumental contingency. In contrast to the results of the first two experiments, however, a reliable reexposure effect was detected after overtraining in a final study, in which the animals were given greater reexposure to the food pellets in the nondeprived state. 相似文献
17.
Two experiments examined the effects of preexposure to a stimulus on the subsequent acquisition of conditioned suppression by rats. Variations in the level of suppression within conditioning trials were noted so thatinhibition of delay (taken here to mean less suppression at the beginning of a trial than at the end) could be detected. Inhibition of delay was observed both during the acquisition of suppression and (in Experiment 1) when suppression began to wane with continued postasymptotic training. Preexposure to the to-be-conditioned stimulus retarded acquisition of suppression and slowed the appearance of inhibition of delay both in acquisition and (in Experiment 1) in postasymptotic performance. Experiment 2 demonstrated that inhibition of delay was attenuated during conditioning that followed preexposure in which the stimulus was paired with a weak reinforcer. These results provide no support for the suggestion that preexposure to a stimulus retards later conditioning because it allows the subject to acquire information about stimulus duration that in turn fosters the development of inhibition of delay. Rather, they are compatible with the suggestion that preexposure causes the stimulus to lose associability. 相似文献
18.
In each of two experiments, rats were trained to press the lever in a Skinner box, food reinforcement being available on a variable-interval 60-sec schedule (VI 60). There followed an “exposure phase” for which the levers were removed from the boxes, and then a final test with the levers replaced to assess the effects of the intervening treatment on instrumental responding. Experiment 1 showed that simple exposure to the box reduced the vigor of instrumental performance in comparison with a condition in which food was made available during the exposure phase. Animals which received no exposure treatment also showed a relatively high rate of response. Experiment 2 demonstrated that an exposure treatment in which the occurrence of food is signaled by a light stimulus also leads to a decline in instrumental responding. These results are held to support the notion that associations between the context and the reinforcer serve to energize appetitive instrumental behavior. 相似文献
19.
Manipulating experience with the reinforcer, through either home cage presentations of Noyes pellets or availability of the free reinforcer immediately prior to testing, attenuated the preference for earned as opposed to free reinforcers. Similarly, changing the reinforcer to one of a different flavor at testing increased the preference for the noncontingent reinforcer. These results are consistent with an interpretation of earned reinforcer preference which emphasizes the role of the reinforcer as a discriminative signal for further instrumental responding. It is suggested that the tendency to perform instrumental responses for reinforcers when free reinforcers are available can be explained in terms of traditional learning processes. 相似文献
20.
In two experiments, rats received preexposure to three compound flavor stimuli, AX, BX, and CX, where X represents a saline
solution. AX and BX were presented in alternation; CX, on a separate block of trials. The value of X was then modified, being
devalued by aversive conditioning in Experiment 1, and rendered valuable by the induction of a state of salt need in Experiment
2. When given a choice between BX and CX, the rats consumed more of BX than of CX in Experiment 1, and more of CX than of
BX in Experiment 2, suggesting that B and C differed in their ability to modulate the response governed by the X element.
It was suggested that blocked preexposure to CX reduces the salience of the C stimulus but that the salience of B is maintained
by preexposure in which BX is alternated with AX. The implications of this result for the phenomenon of perceptual learning
are discussed. 相似文献