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1.
Rats received Pavlovian aversive (shock) conditioning in which white noise was established for different groups as a CS+, CSO, or CS?. Then, in an appetitive T-maze discrimination, the CSs were presented contingent upon a designated correct response for which food reinforcement was factorially varied at 0, 1, 2, or 4 pellets. Although the CS+ suppressed and the CS? facilitated speed of running in the correct arm at the start of discrimination training, these effects extinguished rapidly and did not interact with reward magnitude. Furthermore, choice learning was faciltated by the CS+ and retarded by the CS?, with these effects being comparable for the 1- to 4-pellet reinforcement conditions, but absent for the 0-pellet condition. These findings are difficult to reconcile with a transfer interpretation positing a general signaling property of the CS and are better interpreted as across-reinforcement blocking effects: By predicting a preferred outcome (safety) comparable to the preferred outcome of food reinforcement, the CS? blocks (retards) the association of reinforcement and the SD; conversely, by predicting a nonpreferred (shock) outcome discrepant from the preferred food outcome, the CS+ “counterblocks” (enhances) the association of reinforcement and the SD. 相似文献
2.
Patricia B. Cronin 《Learning & behavior》1980,8(3):352-358
Delayed-reward learning in pigeons was examined using a simultaneous red-green visual discrimination task in which the conditions during the delay interval were varied between groups. The nondifferential group received training in which the stimulus present during the 1-min delay was the same following a peck on the correct and incorrect colors. The other three groups received 1-min delay training in which different stimuli occurred in the delay interval following correct and incorrect choices. The differential group received continuous, differential stimuli during the delay. The reinstatement group received the differential stimuli in the 10 sec immediately following the choice and during the last 10 sec of the delay. The reversedcue group was treated in the same way, except that the 10-sec delay stimulus immediately following an incorrect response was also presented for 10 sec prior to reward on correct choices, and the stimulus following a correct response also occurred 10 sec before nonreward on incorrect choices. Nondifferential birds failed to learn the discrimination, while differential and reinstatement birds learned it readily. The reversed-cue birds learned to choose the incorrect stimulus. Differential and reinstatement birds showed no decrement in performance when the delay was increased to 2 min. These findings suggest that similarity of prereward and postresponse delay stimuli controls choice responding in long-delay learning, a finding compatible with both memorial and conditioned reinforcement interpretations. 相似文献
3.
If rats chose S+ in a brightness discrimination in a T-maze, they experienced, on that run and over four forced runs to S+ which followed, a pattern of reinforcement in which quantity of reward in the goalbox increased from 0 to 14 food pellets, decreased from 14 to 0 food pellets, or varied randomly. If the rats erred and chose S?, reinforcement was withheld, and they were forced a second time to 0 reward in the S? goalbox. The results indicate that rats readily learn the brightness discrimination under these conditions, the animals exposed to the sequentially increasing pattern learning somewhat slower than the others. This was true in spite of substantial delay of reward. Theoretical accounts based on perseverative inhibitory or facilitatory tendencies, or upon frustration, fail to describe the data accurately. Instead, analysis of the data shows that the animals were accurately anticipating the quantity of reward to be obtained on each run, running fast for large quantities and slowly for small.
相似文献4.
Three different techniques were employed to analyze the associative structures mediating performance on an instrumental biconditional discrimination. In all three experiments, rats were trained concurrently on two tasks in which different stimuli signaled which one of two responses would be followed by reward. In each task, one response was rewarded in one stimulus and the other response was rewarded in the other stimulus. Correct responses earned pellets in one task and sucrose in the other task. The transfer procedure was used in Experiment 1A to identify whether or not an association developed between a biconditional discriminative stimulus and its instrumental outcome. Evidence was obtained that a biconditional cue elevated preferentially a new response trained with the same outcome. Experiments 1B and 3 examined the potential contribution of this stimulus-outcome association to biconditional performance by training the biconditional cues as signals (S-s) for the nonreinforcement of a different response. There was no evidence that this operation interfered with the ability of a biconditional cue to control performance of its correct response. In Experiments 1B and 2, the value of the instrumental outcome was reduced in an attempt to assess the contribution of stimulus-response associations to performance on the biconditional discrimination. The results of Experiments 1B and 2 reveal that correct responses were depressed following devaluation of the outcome used to train them, suggesting that learning about the response-outcome relation occurs. The implications of these results for binary and hierarchical models of instrumental learning are discussed. 相似文献
5.
Prior research on Pavlovian-to-instrumental transfer has shown that when a CS previously associated with shock (AvCS+) is presented contingent upon a choice response to a discriminative stimulus for food reinforcement, it facilitates discrimination learning. Conversely, a response-contingent CS previously associated with the absence of shock (AvCS?) retards discrimination learning. To evaluate whether these findings reflect across-reinforcement blocking and enhancement effects, two experiments investigated the effects of appetitively conditioned stimuli on fear conditioning to a novel stimulus that was serially compounded with the appetitive CS during conditioned-emotional-response (CER) training. Although there were no differential effects of the appetitive CSs in CER acquisition, Experiment 1, using a relatively weak shock US, showed that a CS previously associated with food (ApCS+) retarded CER extinction to the novel stimulus, in evidence of enhanced fear conditioning to that stimulus. In addition, Experiment 2, using a stronger shock US, showed that a CS previously associated with the absence of food (ApCS?) facilitated CER extinction to the novel stimulus, in evidence of weaker fear conditioning to that stimulus. These results parallel traditional blocking effects and indicate not only that an ApCS+ and an ApCS? are functionally similar to AvCSs of opposite sign, but that their functional similarity is mediated by common central emotional states. 相似文献
6.
Two groups of pigeons were required to generate a fixed sequence of responses on three keys, for example, middle-left-right. One group received a small food reward (SFood) following each correct response except the terminal one, which was followed by a large food reward. The second group received conditioned reinforcement from an overhead light (SLight) for each correct response, with the terminal correct response followed by both SLight and the large food reward. We manipulated length of sequence (3 or 7 responses) and duration of required interresponse interval (IRI; 1 to 9 sec). SLight contingencies generated more accurate performances than did SFood when sequence length was 3 responses but not when it was 7 responses. IRI duration influenced accuracy under the SLight contingencies but not under SFood. These results show that conditioned reinforcers sometimes generate more accurate sequence learning than do primary reinforcers, and that schedule contigencies influence which type of feedback will optimize performance. The results parallel those from the matching-to-sample and conditional discrimination literature. 相似文献
7.
The greater the dissimilarity between exteroceptive stimuli, the easier it is to discriminate between them. To determine whether a similar relationship holds for memories produced by reward events, rats in three runway investigations received trials in pairs, the number of food pellets (0.045 g) occurring on Trial 1 indicating whether reward or nonreward would occur on Trial 2. In each investigation, discriminative responding on Trial 2 was better the larger the difference in reward magnitude on Trial 1. This finding was obtained under a wide variety of conditions: for example, when the larger of two reward magnitudes on Trial 1 signaled nonreward on Trial 2 (Experiment 1, 10 vs. 2 pellets); when the smaller of two reward magnitudes on Trial 1 signaled nonreward on Trial 2 (Experiment 2, 10 vs. 2 pellets); and when the same magnitude of reward on Trial 1 signaled nonreward on Trial 2 (Experiment 3, either 5 pellets or 0 pellets). The findings obtained here indicate that the greater the dissimilarity between reward magnitudes, the greater the dissimilarity between the memories they produced and, thus, the easier it is to discriminate between them. It is suggested that the present results may provide a basis for understanding findings obtained in other instrumental learning investigations in which reward magnitude is varied. 相似文献
8.
Holly C. Miller Andrea M. Friedrich Randi J. Narkavic Thomas R. ZentAll 《Learning & behavior》2009,37(2):161-166
When differential outcomes follow correct responses to each of two comparison stimuli in matching to sample, relative to the
appropriate control condition, higher matching accuracy is typically found, especially when there is a delay between the sample
and the comparison stimuli. In two experiments, we examined whether this differential-outcomes effect depends on using outcomes
that differ in hedonic value (e.g., food vs. water). In Experiment 1, we found facilitated retention when a blue houselight
followed correct responses to one comparison stimulus and a white houselight followed correct responses to the other, prior
to nondifferential presentations of food. In Experiment 2, we found facilitated retention again when a blue houselight followed
correct responses to one comparison stimulus and a tone followed correct responses to the other, prior to nondifferential
presentations of food. The results of both experiments indicate that the differential-outcomes effect does not depend on a
difference in hedonic value of the differential outcomes, and they suggest that outcome anticipations consisting of relatively
arbitrary but differential stimulus representations can serve as cues for comparison choice. 相似文献
9.
Quantity discrimination abilities are seen in a diverse range of species with similarities in performance patterns, suggesting common underlying cognitive mechanisms. However, methodological factors that impact performance make it difficult to draw broad phylogenetic comparisons of numerical cognition across studies. For example, some Old World monkeys selected a higher quantity stimulus more frequently when choosing between inedible (pebbles) than edible (food) stimuli. In Experiment 1 we presented brown capuchin (Cebus [Sapajus] paella) and squirrel monkeys (Saimiri sciureus) with the same two-choice quantity discrimination task in three different stimulus conditions: edible, inedible, and edible replaced (in which choice stimuli were food items that stood in for the same quantity of food items that were given as a reward). Unlike Old World monkeys, capuchins selected the higher quantity stimulus more in the edible condition and squirrel monkeys showed generally poor performance across all stimulus types. Performance patterns suggested that differences in subjective reward value might motivate differences in choice behavior between and within species. In Experiment 2 we manipulated the subjective reinforcement value of the reward by varying reward type and delay to reinforcement and found that delay to reinforcement had no impact on choice behavior, while increasing the value of the reward significantly improved performance by both species. The results of this study indicate that species presented with identical tasks may respond differently to methodological factors such as stimulus and reward types, resulting in significant differences in choice behavior that may lead to spurious suggestions of species differences in cognitive abilities. 相似文献
10.
An attempt was madeto manipulate the strength of internal stimulus representations by exposing pigeons to brief delays between sample offset and comparison onset in a delayed conditional discrimination. In Experiment 1, pigeons were first trained on delayed conditional discrimination with either short (0.5-sec) delays or no delays. When delays were increased by 2.0 sec, birds trained with a delay performed at a higher level than did birds trained with no delays. In Experiment 2, subjects were first trained on a delayed simple discrimination. Following a circle stimulus, responses to a white key were reinforced; however, following a dot stimulus, responses to the white key were not reinforced. The pigeons were then trained on a delayed conditional discrimination involving hue samples and line-orientation comparisons with differential outcomes. Choice of vertical following red yielded food; choice of horizontal following green yielded no food. Mixed delays were then introduced to birds in Group Delay, whereas birds in the control group received overtraining. When tested on a delayed simple discrimination with hue stimuli (red and green initial stimuli followed by white response stimulus), pigeons in Group Delay tended to perform at a higher level than did birds in the control group (i.e., although the birds in both groups responded more following red than following green, birds in Group Delay did this to a greater extent than did birds in the control group). Thus, experience with delays appears to strengthen stimulus representations established during training. 相似文献
11.
The effect of differential outcome expectancies on memory for temporal and nontemporal information was examined. Pigeons were trained to match short (2-sec) and long (8-sec) sample durations to red and green comparison stimuli, and vertical and horizontal lines to vertical and horizontal comparison stimuli. In Experiment 1, one differential outcome (DO) group received food for correct choices on short-sample trials, whereas another received food for correct choices on long-sample trials. On line-orientation trials, half of each DO group received food for correct responses following vertical samples, whereas the other half received food for correct responses following horizontal samples. Overall retention was greater in the DO groups than in a nondifferential (NDO) group that received either food or no food for correct responses on a random half of all trials. Furthermore, although the NDO group displayed a choose-short bias for temporal samples, both DO groups displayed equivalent biases to select the comparison stimulus associated with food. In Experiment 2, differential outcome expectancies were extinguished off-baseline. Subsequently, in the first nondifferential outcome test session, the. DO groups performed less, accurately than the NDO group. These findings indicate that temporal samples are not retrospectively and analogically coded when they are differentially associated with food and no food. Instead, they are remembered in terms of the corresponding outcome expectancies. 相似文献
12.
Hulse and Dorsky found that rats were better able to track (run slowly to) 0 food pellets in a strongly monotonic (decreasing) serial pattern (14-7-3-1-0 food pellets) than in either a weakly monotonic one (14-5-5-1-0) or a nonmonotonic one (14-1-3-7-0). These findings were seen as incompatible with associative approaches based on animal experiments. Instead, they were taken to be consistent with cognitive theories of human behavior that relate pattern difficulty to formally defined structural complexity. In Experiment 1, tracking was found to be poorer with a strongly monotonie series (15-10-5-0) than with either of two weakly monotonic series (15-15-0-0 or 14-14-2-0), and in Experiment 2 a nonmonotonic series (1-29-0) produced better tracking than a strongly monotonic one (20-10-0). Although these results are not necessarily incompatible with the structural complexity view, they do suggest that “element discriminability” is a factor in serial-pattern learning. They are, therefore, compatible with a memory approach that views tracking as a form of discrimination learning. 相似文献
13.
Douglas S. Grant 《Learning & behavior》1982,10(1):7-14
In two matching-to-sample experiments, pigeons’ performance with samples of stimuli (red and green), number of responses (1 and 20), and reinforcers (food and no food) was assessed. Samples of red, 20 responses, and food were associated with the red comparison stimulus, and samples of green, 1 response, and no food were associated with the green comparison stimulus. On interference trials, three sample types were presented on each trial, and two of the samples (congruent) were associated with the correct comparison and the third sample (incongruent), with the incorrect comparison. Performance on interference trials was compared with that on control trials in which either two (Experiment 1) or three (Experiment 2) congruent samples were presented. It was found that presentation of an incongruent sample reduced matching accuracy markedly, and about equally, whether samples were presented successively or in compound. Although the type of sample that was incongruent was without effect, matching accuracy declined strongly as the recency of the incongruent sample increased. Serial position of the incongruent sample also influenced the shape of the retention function on interference trials. Presentation of the incongruent sample either first or second resulted in accuracy decreasing across the retention interval, whereas presentation of the incongruent sample last in the input sequence resulted in increasing accuracy across the retention interval. The theoretical implications of the findings are considered. 相似文献
14.
When rats receive a sequence of rewards of different magnitudes for traversing a runway, they learn to “track” the sequence, showing anticipation of the forthcoming reward by appropriate running speed. There is disagreement as to whether this behavior depends on rats’ encoding and recalling a complete sequence of foregoing hedonic events or just the immediately preceding one. The present experiments showed that rats can remember more hedonic events than the most recent one. In Experiment 1, when exposed concurrently to the sequences 10-1-0 (pellets) and 0-1-10, they were faster on Run 3 of the increasing than of the decreasing sequence, a discrimination which cannot be made on the basis of the preceding (1-pellet) reward alone. Experiment 2 showed that this behavior reflects genuine anticipation of the Run 3 reward, not simultaneous contrast or other simple aftereffects of Runs 1 and 2. It is argued, however, that these results, together with related findings by Capaldi and Verry (1981), show merely that rats can recall a hedonic event other than the most recent one, not that a sequence of such events is fully recalled in order. 相似文献
15.
A series of four experiments studied the retention of the response made on a just-preceding trial as a function of the presence, and amount, of food reward given on that trial. Rats were trained to alternate arm choices in a T-maze, and then were tested for alternation with 5- or 30-sec delays between runs. When the subjects had received prior experience with the reward amounts used in testing, larger rewards led to better retention than did small or no rewards. However, when reward omission first occurred during the test phase, it produced more alternation on the following trial than did reward presence. The results suggest that both reward amount and surprisingness determine short-term retention of responses paired with the rewards. 相似文献
16.
Ben A. Williams 《Learning & behavior》1991,19(3):264-269
Rats were trained on a series of reversals of a two-choice conditional discrimination. Choice responses were followed by different delays of reinforcement, which were either unsignaled or filled with either a brief or a long tone. In some conditions, the tone occurred following both correct and incorrect choices; in other conditions, the tone occurred only after correct choices. Presentation of the tone following only correct choices greatly facilitated the acquisition of the discrimination, and there was little effect of the tone’s duration. Presentation of the tone following all choices did not improve discrimination acquisition relative to the no-signal condition. The results demonstrate facilitatory effects of a signal during a delay-of-reinforcement interval that are caused by the conditioned-reinforcement properties of the signal and cannot he explained by the alternative mechanisms of marking or bridging. 相似文献
17.
18.
This study explored the visual discrimination learning ability of fire-bellied toads (Bombina orientalis). Two groups of toads were trained in a simultaneous visual discrimination task involving video footage of either black crickets
on a white background (black-cricket toads) or white crickets on a black background (white-cricket toads). Fifteen widely spaced acquisition trials were followed by 12 reversal trials. Successful learning was observed by decreased
incorrect snapping and reduced latency to snap at the correct stimulus (S+) during acquisition; however, white-cricket toads
executed significantly more incorrect snaps than did black-cricket toads. Both groups of toads could master the reversal task
as measured by latency to snap at S+, but not as measured by the proportion of incorrect snaps. Despite the stronger potency
of the black-cricket stimulus, the results showed that toads can learn a simultaneous discrimination task and a reversal of
its contingency. This elaborate form of learning appears to be conserved among vertebrates. 相似文献
19.
Eight homing pigeons, trained to fly between two elevated feeders within a flight tunnel, were tested for their ability to discriminate between two magnetic field stimuli and two acoustic stimuli, using a unitary discrete-trials procedure with successive presentation of stimuli. Magnetic stimuli consisted of the ambient magnetic field and a reduced magnetic field in which the vertical component of the field was reduced to 50% of its ambient value. Acoustic stimuli consisted of an ambient white noise and the white noise plus a tone. Stimuli were paired with food reward and either a time penalty (Experiment 1) or electric shock (Experiment 2). Although subjects could discriminate sounds with our procedures, none of the subjects demonstrated discrimination of magnetic fields. The failure of pigeons to discriminate magnetic stimuli is discussed as a consequence of either the failure to provide conditions sufficient for such discrimination or the absence of a magnetic sense in these animals. 相似文献
20.
In simultaneous matching-to-sample and oddity-from-sample tasks, briefly delaying the offset of trial stimuli following an incorrect choice response was found to facilitate task acquisition (Experiment 1). Because thispenalty-time procedure also resulted in longer choice-response latencies, it was hypothesized that any procedure that increased response latency would facilitate task acquisition. However, in Experiment 2, no evidence of facilitation was found when a 2-sec pause was imposed prior to the choice response. The results of Experiment 3 suggest that penalty-time facilitation of acquisition was not due to either the added differential outcome on correct versus incorrect trials (i.e., incorrect choice responses do not darken the keys as do correct choice responses) or the aversive effects associated with trial prolongation (i.e., incorrect responses not only result in the absence of reinforcement but also delay the start of the next trial). Instead, results suggest that birds trained with the penalty-time procedure review the trial stimuli following an incorrect choice. 相似文献