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1.
Two experiments tested the effects of food deprivation on discounting in pigeons. An adjusting-amount procedure was used to estimate the subjective value of food at delays ranging from 1 to 24 s. Experiment 1 compared pigeons’ discounting of delayed food reinforcers at 75 %–80 % and 90 %–95 % of free-feeding weight. Experiment 2 compared discounting under 1- and 23-h food deprivation. In both experiments at both deprivation levels, discounting was well described by the hyperboloid discounting function. No systematic effect of level of deprivation on degree of discounting was observed in either experiment. This finding is consistent with the view that pigeons’ choices are controlled by the relative, rather than the absolute, value of reinforcers. 相似文献
2.
The role of incentive learning in instrumental performance following an upshift in the degree of water deprivation was analyzed in three experiments. In Experiments 1A and 1B, rats trained to perform an instrumental action reinforced by either sucrose or maltodextrin solutions when in a low-deprivation state were shifted to a high-deprivation state and tested in extinction. This shift in water deprivation increased performance only if the animals had been exposed to the reinforcer in the high-deprivation state prior to testing. In Experiment 2, the role of the instrumental contingency in mediating the preexposure effect observed in the first two studies was examined by training rats to make two instrumental actions for different outcomes. The preexposure experience with the outcomes produced a relative increase in performance of the action reinforced with the incentive preexposed in the high-deprivation state when a choice between the two response alternatives was conducted in that state. These experiments support the conclusion that instrumental performance following revaluation of the reinforcer by an upshift in the level of thirst depends on a process of incentive learning. 相似文献
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4.
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
5.
In four experiments, rats’ preferences for flavors consumed under high deprivation versus low deprivation were measured. In Experiment 1, rats preferred flavors received in unsweetened food under high deprivation to flavors received in unsweetened food under low deprivation. This preference did not vary with amount of food used to deliver the flavors (1-g vs. 16-g wet mash). Sweetening the food (0.10% saccharin) eliminated this preference when 16 g of mash was received, but not when 1 g of mash was received (Experiments 2 and 3). Sweetening the mash even more (0.15% saccharin) eliminated the preference when 1 g of mash was received, as well as when 20 g of mash was received. We suggested that the reinforcing value of sweetness is reduced by increasing deprivation level. 相似文献
6.
In Experiment 1, the form of keypecks produced in an autoshaping procedure with food or water reinforcers was compared with that of eating and drinking responses. Because the responses involve a number of different effector systems, several elements of response form were measured, including peck force and duration, gape, and eye closure. Gape was the only measure to reliably distinguish between both ingestive responses and between conditioned keypecks reinforced with food or water. With either reinforcer, keypecks had greater force than did ingestive behaviors. In Experiment 2, a transition between two forms of keypeck was produced by manipulating deprivation and reinforcer conditions. Some measures appeared to vary in a dichotomous manner between two discrete response forms; gape showed a gradual and continuous change involving the production of intermediate forms of the response. It was concluded that the control of conditioned response form involves theconstruction of the response from movements produced by several effector systems, each with potentially different sources of control. 相似文献
7.
Robert A. Rosellini 《Learning & behavior》1978,6(2):155-159
This article reports the reinforcer generality of the interference effect resulting from exposure to inescapable shock. In Experiment 1, rats that received inescapable shock showed weak interference with the acquisition of an appetitive operant compared to animals exposed either to escapable or no shock. In Experiment 2, the response-reinforcer contingency was degraded by introducing a 1-sec delay of reinforcement on the appetitive task. Inescapable shock produced much stronger interference with the acquisition of the operant response than in Experiment 1. The results demonstrate reinforcer generality of the debilitating effects produced by inescapable shock. 相似文献
8.
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
9.
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
10.
Kelly J. Stanhope 《Learning & behavior》1989,17(3):311-321
A dissociation between the effect of reinforcer type and response strength on the force of the pigeon’s keypeck response was shown in three experiments. In Experiment 1, pigeons were trained to peck two conditioned stimuli, one paired with water and another paired with grain. The pigeons made more forceful pecks for grain than for water and also showed a tendency, albeit an unreliable one, to respond on a higher percentage of food trials than water trials. In Experiment 2, the pigeons from Experiment 1 were satiated with either food or water and were then presented with the two conditioned stimuli in an extinction test. It was found that, regardless of the drive state, the pigeons made more forceful pecks to the stimulus that predicted food than to the stimulus that predicted water. In the thirsty group, however, this difference in force was not accompanied by a difference in the percentage of trials with a response. In Experiment 3, pigeons trained with a single reinforcer pecked more often on instrumentally reinforced trials than on Pavlovian conditioning trials, but there was no difference in the force of the pecks. Taken together, these results imply that differences in response strength cannot account for the difference between the force of food- and water-reinforced pecks. Instead, stimulus-substitution theory may provide the best account of the topography of the two types of pecks. 相似文献
11.
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
12.
Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables. 相似文献
13.
In four experiments, food deprivation was varied during conditioning and testing of conditioning of flavor preferences by sweeteners. Conditioned preferences for a flavor associated with a more concentrated solution were enhanced by increased deprivation in training whether sucrose or saccharin was used when rats consumed solutions freely during training. When consumption of solutions was controlled and higher deprivation levels were used, preference for the higher concentration of sucrose was still enhanced by increased deprivation in training, but this did not occur with saccharin. We suggest that deprivation may enhance the reinforcing value of sweetness only when calories increase along with sweetness. We also suggest that deprivation can enhance flavor preference learning by increasing consumption and thereby increasing exposure to the flavored solutions. 相似文献
14.
Newly hatched chicks were force-fed food and water throughout rearing, and food, water, or sand reinforcers during exposure to an omission-training procedure. The chicks were thus prevented from performing approach and contact responses to the reinforcer at any time in their lives. Nevertheless, the subjects displayed approach and species-specific feeding or drinking reactions directed toward an illuminated key paired with food or water, but not with sand. Illumination of a key either uncorrelated or negatively correlated with food or water did not engender appreciable responding. Feeding and drinking reactions were topographically distinct, determined by the type of reinforcer, but were not elicited by the reinforcer. These findings support a “learned release” view of autoshaping, according to which phylogenetically preorganized behavior patterns are triggered by distal stimuli paired with biologically significant proximal stimulation, and suggest a close relationship between autoshaping and primitive instances of visual object recognition. 相似文献
15.
In two experiments, pigeons' responding on an extraneous task was explicitly reinforced during delayed matching-to-sample
trials. In Experiment 1, red or green sample stimuli were followed by retention intervals of 0.2, 1, 4, or 12 sec, during
which pecks to a white center key were reinforced with 2.5-sec access to wheat according to extinction, variable-interval
30-sec, and variable-interval 15-sec schedules in different conditions. A proportion of .2, .5, .7, or .9 of subsequent red
or green choice responses that matched the sample were reinforced with 3-sec access to wheat. The result was that increasing
center key reinforcement, or reducing reinforcer probability, lowered overall accuracy. Initial discriminability fell, but
with no change in the rate of forgetting. In Experiment 2, initial discriminability was affected by extraneous reinforcers
that were contingent on center key pecking, but not by noncontingent reinforcers. A plausible conclusion is that initial discriminability
decreases when reinforcers strengthen competing behaviors. 相似文献
16.
Anthony Dickinson 《Learning & behavior》1976,4(4):416-420
In Experiment 1, four groups of rats received conditioned suppression training in which a tone was reinforced with shock. If the tone had been previously paired with response-independent food, aversive conditioning was slightly facilitated by comparison to control groups preexposed either to the tone randomly associated with food or to the tone and food unpaired. However, by comparison to a control which was not preexposed to the tone, animals receiving prior pairings of the tone and food showed retarded aversive conditioning. Experiment 2 replicated the facilitation in aversive conditioning after the tone had been paired with food relative to the random control condition and demonstrated that this difference occurred even if the tone and background stimuli continued to be associated with response-independent food during aversive conditioning. This result suggests that pairing a stimulus with an appetitive reinforcer reduces the retardation of aversive conditioning produced by stimulus preexposure. 相似文献
17.
In the first four experiments, it was found that aversions to saccharin solution produced by contingent poisoning were similar regardless of whether the rats had been trained under the test deprivation or under a different deprivation; the two deprivation states used were thirst and satiety. In Experiment 5, rats were poisoned after drinking grape juice while hungry or poisoned after drinking milk while thirsty, but they were not poisoned after grape-thirst or milk-hunger combinations. In abstract terms, poisoning occurred after AX and BY stimulus combinations, but did not occur after AY and BX combinations. There was some learning under these discrimination conditions. 相似文献
18.
Two experiments are reported on the elimination of autoshaped keypecking in pigeons by introducing added feedings that have the effect of removing the contingency between keylight (CS) and feedings. In Experiment 1, added feedings were signaled, by an already conditioned stimulus, in one group but not in another. Contrary to the Rescorla-Wagner theory, but consistent with scalar expectancy theory, responding in these groups declined at equal rates. In Experiment 2, following acquisition, some groups were exposed to repeated sessions in which they received feedings alone prior to receiving both CS and feedings noncontingently. Although prior exposure to feedings did reduce the total amount of responding in subsequent noncontingent sessions, it did not, contrary to scalar expectancy theory, reduce the initial level of responding to the CS. It is suggested that a differential between reinforcing conditions in the CS as compared with neighboring non-CS periods is more fundamental to conditioning than is acknowledged in the Rescorla-Wagner theory or in scalar expectancy theory. 相似文献
19.
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
20.
Pigeons were exposed to fixed-time and fixed-interval schedules that ranged from 30 to 960 sec. The probability of a subject’s location in the rear of the chamber (away from the reinforcer dispenser) peaked during the postreinforcer period, and was referenced to proportional time between reinforcers. Increasing the interreinforcer interval generally increased time in the rear. In some sessions (Experiment 1), location in the rear produced an explicit stimulus change (altered the color and intensity of lights, i.e., time-out); this change increased time spent in the rear without affecting its temporal locus or its relation to the interreinforcer interval. During Experiment 2, a keypeck (near the reinforcer site) produced the explicit stimulus change used in Experiment 1. The characteristics of keypeck time-out resembled those of movement to the rear of the chamber (with and without an explicit stimulus change), suggesting that movement away from the reinforcer site is functionally homologous to keypeck time-out. 相似文献