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1.
Pigeon subjects received training of a diffuse stimulus as either a conditioned inhibitor or a conditioned facilitator of a keylight signal for food. The ability of these diffuse stimuli to modulate responding was then assessed with two other keylights that were undergoing discrimination reversal. At a point where responding was equivalent for the two targets, the modulators had a greater impact on the target undergoing extinction than on the target undergoing acquisition. These results have implications for the nature of modulation and extinction. 相似文献
2.
Pigeon subjects received Pavlovian conditioning with stimulus elements and were then tested with compounds of those elements. Experiments 1–3 used localized keylight elements and found no evidence for greater responding to the compound than to the elements. Experiments 4A–4D found evidence for greater second-order conditioning by a compound of two elements than by the elements themselves when the elements consisted of two diffuse stimuli or one diffuse stimulus and one localized keylight. No greater second-order conditioning resulted from a compound of two localized keylight elements, suggesting the possibility of perceptual interactions that reduce identification of the elements in the compound. Experiment 6 found evidence of summation when that interaction was reduced by sequential presentation. However, one attempt to capture this interaction in terms of configural conditioning (Pearce, 1987) failed to receive confirmation. These results suggest that the localized stimuli conventionally employed in autoshaping experiments may show such substantial perceptual interaction as to recommend against their routine use for studying conditioning in compounds. 相似文献
3.
Robert A. Rescorla 《Learning & behavior》1988,16(2):169-176
Three experiments were conducted using an autoshaping procedure in pigeons to examine the conditions under which facilitation develops toB in anA? IBA+ paradigm. WhenB is a diffuse stimulus and A is a localized keylight, this paradigm results in B’s facilitating pecking at A. Prior inhibitory conditioning ofA promoted the development of this facilitation more successfully than did prior excitatory or control treatment of A. These results suggest that facilitation develops especially well when an inhibitory stimulus is reinforced in the presence of the diffuseB. That outcome is consistent with the view that facilitation involves the removal of inhibition. 相似文献
4.
In three experiments, we sought evidence for the acquired equivalence of cues in pigeons trained in an autoshaping paradigm. In Experiment 1, presentations of each of a pair of cues (different keylight stimuli) preceded a common consequence (a different keylight stimulus). The pattern of response then established by further training given to one member of the pair was found to generalize preferentially to the other, demonstrating equivalence between cues that had shared a common consequence. The same test procedure was used in Experiment 2, but with a training procedure in which each cue of a pair was preceded by a given stimulus. This too resulted in enhanced generalization between members of the pair, showing that equivalence can be established when cues have been experienced along with a common antecedent. Both training procedures were combined in Experiment 3 to confirm the reliability of the effects previously obtained. The discussion is focused on ways in which the associative explanation offered for cases of equivalence mediated by a common consequence might be extended to accommodate equivalence mediated by a common antecedent. 相似文献
5.
In Experiment 1, the development of autoshaped pecking to a keylight signaling food was blocked if the keylight was presented only in conjunction with another stimulus already established as a signal for food, even though the blocking stimulus (either an overhead light or a train of clicks) never elicited pecking itself. In Experiment 2, pigeons came to peck a white keylight which signaled the presentation of a red keylight which had earlier been established as a first-order signal for food, but this second-order autoshaping was blocked if the white keylight was presented only in conjunction with the houselight or clicker which had previously signaled the presentation of the first-order stimulus. Second-order autoshaping was thus blocked in the same way as was first-order autoshaping. 相似文献
6.
Two experiments assessed the degree to which Pavlovian facilitators were interchangeable with instrumental discriminative stimuli (Sds). In Experiment 1, rats were trained in a Pavlovian paradigm in which one stimulus (i.e., a facilitator) signaled the reinforcement of another stimulus (i.e., a target). Next, the rats were given instrumental discrimination training in which an Sd signaled the reinforcement of barpressing. A transfer test then assessed the capacity of the Pavlovian facilitator to promote barpressing. The results showed that the facilitator promoted significant barpressing, both when it was presented alone and when it was presented in compound with the Sd. Reliable transfer was not obtained with a “pseudofacilitator” control stimulus that, during training, was uninformative about the reinforcement of its target. Experiment 2 showed that a stimulus trained as an instrumental Sd reliably augmented responding to a stimulus previously trained as a target in a Pavlovian facilitation paradigm. A “pseudo-Sd” that, during training, was uninformative about the reinforcement of barpressing failed to promote such transfer. These results show that Pavlovian facilitators and instrumental Sds are interchangeable to a significant degree, and suggest that facilitators and Sds may act via similar mechanisms. 相似文献
7.
Leon R. Dreyfus J. Gregor Fetterman D. Alan Stubbs Susan Montello 《Learning & behavior》1992,20(2):135-145
Pigeons were presented on each trial with a pair of keylight stimuli that varied in duration. One of two subsequent choices was reinforced, depending on which of the two stimuli was longer. For some pairs, the duration of one stimulus was predictive of relative duration, but for other pairs, absolute duration was unpredictive. Choice responses depended on relative differences between the stimuli, but were also controlled to some degree by absolute duration of the second member of the pair. Individual differences in control by absolute and relative duration were evident. Those pigeons whose behavior was most influenced by absolute duration showed poorer transfer to a different set of duration pairs. 相似文献
8.
In the present study, we examined whether the presentation of postevent cues would bias recognition in a visual delayed matching-to-sample task with pigeons. Postevent cues were either consistent with the original target stimulus (i.e., they were the same as the correct choice option at recognition), inconsistent (i.e., they were the same as the incorrect recognition option), or neutral (i.e., they were different from both the correct and the incorrect recognition options). In Experiment 1, a single colored light served as the target stimulus. In Experiment 2, the target stimulus was one of three lights presented in a sequence. Both experiments demonstrated that recognition choices were biased toward the option corresponding to the postevent cue, but only if the cue occurred at the end of the delay interval. The present results mirror those found using the misinformation paradigm with human subjects. 相似文献
9.
A second-order autoshaping procedure was used to examine the effects of three variables on the amount of information that could be learned about the stimulus properties of a reinforcer. All three experiments paired several keylight S2s with different keylight S1s and then carried out discriminative autoshaping with those S1s. Learning about the stimulus properties of S1 was inferred from changes in the response to its paired S2 when that S1 was changed in value. The sensitivity of S2 to changes in S1 was investigated as a function of number of S2-S1 pairings (Experiment 1), partial reinforcement (Experiment 2), and temporal distance between S2 and S1 (Experiment 3). Each experiment found evidence of a selective change in responding to an S2 as a function of the treatment of its S1. However, the amount of that change was not affected by any of the three variables studied. Those results imply that, within the ranges used here, none of these variables changes the degree of learning about the stimulus properties of a reinforcer. 相似文献
10.
Ben A. Williams 《Learning & behavior》1978,6(4):371-379
Pigeons were trained on a discrete-trial delayed reinforcement procedure with respect to one response key that was periodically illuminated. In some conditions, a second response key, or a tone, both previously paired with reinforcement, was interpolated in the delay-of-reinforcement interval. In comparison to a control condition with neither stimulus in the delay interval, the interpolated stimulus attenuated (blocked) the amount of responding that was maintained by the delayed reinforcement contingency. The degree of blocking was unaffected by whether the interpolated stimulus was the tone or keylight, in spite of the fact that the keylight evoked responding and the tone did not. A second study showed that the blocking effects involved the response-reinforcer association in that blocking occurred when the delayed reinforcement was response-dependent but did not occur when reinforcement was response-independent. The results thus show that response-reinforcer associations are affected by informational variables in the same manner as has been shown for stimulus-reinforcer associations. They also demonstrate that preexisting stimulus-reinforcer associations can block response-reinforcer associations, thus suggesting that both types of association depend upon the same associative process. 相似文献
11.
Eliot Hearst 《Learning & behavior》1989,17(3):280-290
During training intended to establish positive and negative backward associations, pigeons received periodic 3-sec illuminations of a grain magazine, with food simultaneously available on 50% of the illuminations. For backward-positive subjects, a red keylight followed food trials only; for backward-negative subjects, it followed no-food trials only. During this training, the birds hardly ever pecked the red stimulus (no evidence of backward conditioning). However, when the red stimulus subsequently preceded and signaled grain for all birds, the backward-positive subjects pecked sooner and more often than did the backward-negative subjects, and control subjects performed at an intermediate level. Increases in the amount of original training did not significantly change the facilitatory effects of the backward-positive stimulus, but seemed to enhance the retarding effects of the backward-negative stimulus. These group differences cannot be attributed to what happened after the backward stimuli during original training. The features of the present technique that could possibly have produced strong and long-lasting positive and negative backward associations are discussed in comparison to prior research that has indicated weak or transitory evidence of true backward conditioning. 相似文献
12.
Pigeons learned to peck a keylight (S2) when it was paired with a stimulus (S1) that already evoked keypecking. Control procedures showed that S2 acquired control over responding because it was paired with S1 and because S1 had a conditioning history, thereby supporting the claim that S2 was a second-order conditioned stimulus. Second-order conditioning occurred as rapidly when S1 was a keylight as when it was a tone. Test procedures showed that after second-order conditioning, responding to S2 was markedly debilitated by the extinction of responding to S1, indicating that the ability of S2 to evoke a response importantly depends upon the continued ability of S1 to do so. Our demonstration that directed motor action in the pigeon is susceptible to second-order conditioning suggests a new interpretation of conditioned reinforcement in instrumental learning. Our demonstration that the effectiveness of S2 depends upon the continued effectiveness of S1 indicates that S-S associations are formed in this version of the second-order conditioning experiment. 相似文献
13.
Robert A. Rescorla 《Learning & behavior》1991,19(4):355-360
In two autoshaping experiments, pigeons received training of several modulators with each of two target excitors. Experiment 1 used a conditioned-facilitation (A?/XA+) procedure, and Experiment 2 used a conditioned-inhibition (A+/XA?) procedure. In the first procedure, the X modulators promoted responding to A, whereas in the second they depressed responding to A. Pairs of the X modulators were then presented in conjunction with a novel target stimulus, B. The ability of those pairs to modulate responding to B was greater when the modulators in a pair had both been trained with the same A stimulus rather than with different A stimuli. That suggests an involvement of the original training targets in the transfer of modulators to a novel target. 相似文献
14.
In Experiment 1, two groups of pigeons (n = 8) were given nondifferential (ND) training with a green keylight and a white vertical line on a dark surround nonsystematically alternated. Two groups (n = 8) received single stimulus (SS) training with the green light only. In Experiment 2, two groups of pigeons (n = 8) were given ND training with vertical and horizontal lines, while two other groups (n = 8) received SS training with only the vertical line. In both experiments, all groups were transferred to a green S+ (VI reinforced) and a red S? (extinguished) transfer problem. In each experiment, one ND and one SS group was tested in the same context as initial training (houselight off) and one ND and one SS group was tested in a changed context (houselight on). In both experiments and in both contexts, the ND groups performed less well on the transfer problem than did the SS groups. There was no evidence of greater control by the context in ND than in SS groups, which suggests that the observed difference in acquisition of the transfer task is not attributable to a purported difference in control by the context under the two conditions. The overall results favor the position that nondifferential training reduces attention to stimuli involved in the original training procedure and that this reduced attention transfers to stimuli subsequently experienced. 相似文献
15.
Three experiments, using rats, demonstrated the encoding of a food unconditioned stimulus (US) in a simple Pavlovian conditioning paradigm. In all three studies, one stimulus was used to signal the delivery of pellets and a different stimulus was used to signal the delivery of sucrose. In Experiment 1, postconditioning devaluation of one of the food USs selectively reduced the frequency of conditioned magazine-directed behavior during the stimulus trained with that US. In Experiment 2, transfer of the stimuli to instrumental responses resulted in selective depression of the response trained with a different outcome. In Experiment 3, acquisition of stimulus-outcome learning was impaired by unsignaled intertrial presentations of the same outcome but not of a different outcome. These results indicate that a detailed representation of the outcome is encoded in the normal course of Pavlovian conditioning. 相似文献
16.
Autoshaping procedures with pigeons were used to assess the susceptibility of unconditioned response (UR) activity to Pavlovian relations between stimulus and reinforcer events. Foodpeck latency (a measure of UR activity) was investigated as a function of the interval between stimulus (keylight) and reinforcer (grain) presentations, and of the stimulus-reinforcer contingency, that is, the conditional probabilities of reinforcer delivery in the presence and absence of the stimulus. Four experiments indicated that food-peck latency was sensitive to both manipulations. Generally, conditions that led to higher keypeck rates were associated with shorter latencies. Thus, UR potentiation was demonstrated. However, when the bird’s location prior to grain delivery was fixed by imposing a keypeck-reinforcer contingency, UR potentiation vanished; it then reappeared when the location constraint was removed. Visual observations supported the conclusion that food-peck latency effects were mediated by approach/withdrawal tendencies generated by the stimulus-reinforcer relation. Implications of these results for expectancy theory are discussed. 相似文献
17.
In two experiments, behavioral stereotypies elicited by scheduled presentations of food and water were compared. In Experiment 1, pigeons were exposed to a fixed-time 30-sec (FT 30-sec) schedule of food or water deliveries with a brightening keylight stimulus signaling time to the unconditioned stimulus (UCS) on each trial. Food and water presentations both produced terminal autoshaped keypecking that was similarly distributed in the trial but differed in response topography and persistence. Locomotor interim behavior was different in the two motivational conditions: With food presentations, it consisted of a “retreat” to the rear of the chamber after UCS termination, followed by “pacing” in the midportion of trials. The water schedule produced very little locomotor activity with no regular distribution in the trial. Experiment 2, using a random-time 30-sec (RT 30-sec) schedule, showed that the differences in interim locomotor behavior persisted in the absence of temporal predictability of the UCS and the keypecking terminal response. The results are taken to support Timberlake’s (1983a) behavior-system theory. 相似文献
18.
Little responding develops to a conditioned stimulus (CS) that is placed in a random relation to an unconditioned stimulus (US). However, if the USs not preceded by that CS are themselves signaled by another stimulus, then the CS does come to elicit responding. This result has been attributed (e.g., by Durlach, 1983) to the signal’s blocking of conditioning to background cues that otherwise would prevent conditioning of the CS. However, Goddard and Jenkins (1987) have suggested the alternative that signaling the USs promotes responding due to the adventitious creation of periods of signaled nonreinforcement. Two experiments were conducted to assess this alternative, involving an autoshaping preparation in pigeons. In Experiment 1, little responding to a keylight CS presented in a random relation to a food US occurred, despite the explicit presentation of a discrete noise signaling periods of no food in the intertrial interval (ITI). Experiment 2 was designed to replicate the procedure of Goddard and Jenkins, in which an auditory stimulus extended throughout the ITI of a random schedule, terminating only prior to extra USs and during the CS. Contrary to their findings, little responding developed to the target CS. However, responding did develop when the sound-free period occurred only prior to the extra USs. These results offer little support for the hypothesis that signaled periods of nonreinforcement promote responding on random schedules. However, they are consistent with the view that signaling of ITI USs acts by preventing conditioning of potentially competitive background cues. 相似文献
19.
In two experiments, rats solved two concurrent discrimination problems in which one stimulus (i.e., a facilitator) signaled the reinforcement of another stimulus (i.e., a target). Then a transfer test assessed the capacity of facilitators trained in one problem to promote responding to targets trained in the other. Experiment 1 found that a facilitator promoted as much responding to such a transfer target as to the target with which it was originally trained. Transfer was not obtained with a pseudofacilitator that was uninformative, in training, about the reinforcement of its target. Experiment 2 manipulated the stimulus modality of the targets and facilitators. Its results indicated that transfer performance was not due to generalization between training and transfer targets or facilitators. These results parallel those from comparable autoshaping paradigms with pigeons, and they agree with the view that facilitators promote responding by lowering the threshold for activation of the US representation. 相似文献
20.
Pigeons were given successive discrimination training in which pecking during a choice period when the key was white was either reinforced or not, depending upon the prior presence or absence of a discriminative stimulus, which was a two-element serial compound. The compound consisted of a keylight and food, with food presented second or first in a forward or backward pairing for different groups of pigeons. In Experiment 1, the sequence was an S+ indicating reinforced trials, while in Experiment 2, the sequence was an S? indicating nonreinforced trials. Following acquisition of discriminated operant behavior, a sequence generalization test was administered during which all possible orders of the two stimuli were presented on test trials prior to the onset of the choice period. The results showed that food overshadowed stimulus control by the color of the light on the key on the sequence-generalization test, independently of whether food was presented first or second during training and independently of whether food was associated with reinforcement or nonreinforcement. The similarity of results for the two experiments suggests that overshadowing occurs independently of whether the compound is a discriminative stimulus for reinforcement or nonreinforcement. Simultaneous presentation of elements of a compound stimulus is not necessary for overshadowing because the phenomenon was captured with sequentially presented stimuli. 相似文献