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1.
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
2.
Robert A. Rescorla 《Learning & behavior》1991,19(1):65-70
An autoshaping paradigm with pigeon subjects was used to study two-types-of modulation: facilitation and inhibition. In each paradigm, a diffuse stimulus signaled when a keylight would be reinforced. Transfer of that diffuse stimulus to a different keylight was assessed after the response-evoking power of the original keylight had been altered in the presence of a different modulator. That alteration of the original target produced a specific change in the transfer of modulators trained with that target. The results are interpreted as suggesting that transfer to another target stimulus is partly mediated by the association of the original target with the reinforcer. They are inconsistent with at least one version of a configurai cue interpretation. 相似文献
3.
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
4.
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
5.
In a Pavlovian conditioning situation, an initially neutral stimulus may be made excitatory by nonreinforced presentations
in compound with an established conditioned excitor [i.e., second-order conditioning (SOC)]. The established excitor may be
either a punctate cue or the training context. In four conditioned suppression experiments using rats, we investigated whether
SOC phenomena parallel other cue interaction effects. In Experiment 1, we found that the response potential of a target stimulus
was directly related to the intertrial interval when SOC was mediated by a punctate cue, and inversely related to the intertrial
interval when SOC was mediated by the training context. Experiment 2 demonstrated that punctate- and context-mediated SOC
are oppositely affected by posttraining context extinction, and Experiments 3 and 4 demonstrated that context- and punctate-mediated
SOC are differentially affected by conditioned stimulus (Experiment 3) and unconditioned stimulus (Experiment 4) preexposure
treatments. These findings parallel phenomena in conditioned inhibition and cue competition situations. 相似文献
6.
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
7.
Four experiments were performed to determine the stimulus characteristics that favor the development of conditional stimulus control in the single reversal paradigm with pigeon subjects. In Experiment 1, pigeons were trained on a successive discrimination between tone frequencies ranging from 350 to 3500 Hz in a particular houselight context condition (houselight-on or -off). The subjects then were trained on the reversal of the tone discrimination in the alternative context. Subsequent tone-frequency generalization testing in the two contexts indicated that they had failed to gain conditional control over the pigeons’ discriminative performance. Such control was obtained in Experiment 2, in which the two problems were alternated daily for 32 sessions of training. The gradients then peaked at the appropriate S+ value in each context. In Experiment 3, the key colors (blue vs. red) served as contexts while pigeons learned a successive discrimination in which the discriminative cues were houselight-on versus houselight-off conditions. This was followed by a reversal of the discrimination in the alternative key-color context condition. The key colors were effective conditional cues in this situation. In a previous experiment (Thomas, McKelvie, & Mah, 1985), key color had been ineffective as a conditional cue when the discriminative cues were lines superimposed on the colored background. In Experiment 4, key color was effective when the color and lines were presented on a single key as in the earlier experiment, but were sequenced such that the onset of the key color preceded and then overlapped the presentation of the lines. We concluded that conditional discriminations are easiest for pigeons when visual cues are used, but the conditional and discriminative cues must be presented in such a way that they do not combine to form a psychological compound. 相似文献
8.
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
9.
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
10.
In Experiment 1, six groups of pigeons (n=8) were tested for wavelength generalization either immediately or 24 h after learning a successive discrimination, with 550 nm reinforced and a black vertical line extinguished. The groups differed in the stimulus present during single stimulus pretraining, which was 550 nm (pretrain S+), the vertical Une (pretrain S?), or a neutral dim white light (pretrain Sn), respectively. The three immediate generalization gradients were steep and indistinguishable, reflecting only the immediately preceding discrimination training condition. The three delay gradients were flatter, with the flattening particularly marked in the pretrain S? group. This was interpreted as proactive interference (PI) resulting from the memory that both the 550-nm and the line stimuli had previously been reinforced. In Experiment 2, two (TD) groups of pigeons (n=16) were given single stimulus training with a 555-nm keylight followed by eight sessions of discrimination training with two line angles, then one session of non-differential (ND) training with the same two lines, and then a wavelength generalization test either immediately or after a 24-h delay. Two other (hold) groups (n=16) received similar training, except for the TD Une angle training sessions, in these hold groups, the wavelength gradient was flatter in a delayed test; in the TD groups it was steeper, indicating PI from the prior TD training. These two experiments suggest that the “attentional sets,” which purportedly result from TD and ND training, may fruitfully be viewed as target memories subject to the principles of interference theory. 相似文献
11.
In three between-groups blocking experiments with rats, two concurrent and one forward, several common control procedures
were employed: Reinforced trials with the putative blocking stimulus were either omitted entirely (Kamin control), replaced
by unsignaled reinforcements (Wagner control), or replaced by reinforced trials with a different stimulus (C1 control). In
each experiment, parallel treatments with the target stimulus absent during training served to examine the possibility that
differential responding in tests with the target stimulus might be traced solely to differential exposure to the nontarget
stimuli. In Experiment 1, responding by a concurrent blocking group during the test was no different than responding by a
Kamin control group, and responding by a Wagner control group was greater than that of either of the other groups—a pattern
of results, mirrored in the performance of the target-absent groups, that could be attributed to the elevation of contextual
excitation by unsignaled reinforcement. In Experiment 2, responding in the test by a concurrent blocking group was no different
than that by a C1 control group. In Experiment 3, a finding of less responding by a forward blocking group than by a C1 control
group when the target stimulus was present during training, but not when it was absent, provided plausible evidence of blocking. 相似文献
12.
Most associative theories have assumed that stimulus competition occurs only between conditioned stimuli (CSs) that are trained in compound. The present research investigated the possibility of competition between two CSs that were individually paired to the same unconditioned stimulus (US). We used human subjects in an anticipatory suppression analogue to Pavlovian conditioning. Experiment 1 showed that X+ training followed by A+ training resulted in impaired responding to X. This did not occur when A+ training preceded X+ training. Experiment 2 replicated the basic effect and showed that it did not occur when the Phase 2 training consisted of A? instead of A+ nor when the A+ pairings occurred in a second context. Experiment 3 showed that A+ pairings occurring in a second context could still produce the effect when X was tested in the context in which the A+ pairings had occurred, but not when X was tested in a context different from that used for A+ training. Collectively, these results suggest that individually trained CSs may compete with each other when one of those CSs is more strongly activated by the test context than the other one. 相似文献
13.
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
14.
The relationship between the duration of stimuli and their conditioned reinforcing effect was investigated using a learning-tests procedure. In Experiment 1, stimuli were the same duration on training (stimulus → reward) and test (choice response → stimulus). Ten- and 30-sec stimuli provided effective differential conditioned reinforcement but 3-sec stimuli did not. In Experiment 2, different pigeons had each combination of the 3- and 30-sec stimuli on training and test trials. Evidence of conditioned reinforcement was obtained only for the birds with 30-sec stimuli on both training and test. The results were interpreted as indicating that stimuli become effective conditioned reinforcers on test trials only when their duration exceeds the duration of differential short-term memory cues resulting from a difference in the events that precede them on training and test trials. 相似文献
15.
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
16.
Ruth M. Colwill 《Learning & behavior》1993,21(4):337-345
The effect of training a positive discriminative stimulus (S+ ) as a signal for the nonreinforcement of an instrumental response (S?) on the ability of that stimulus to evoke its original instrumental response was examined in three experiments using rats. In all three experiments, two different stimuli were established as S+s for different response-outcome relations. In Experiment 1, an S+ was less effective in controlling its original response after it had undergone training as an S? for a new response that earned the same outcome than it was after training as an S? for a response that earned a different outcome. Experiment 2 established that this effect was not mediated by Pavlovian inhibitory conditioning produced by the negative correlation between the S+ and the outcome during S? training. Simply arranging a negative correlation between S+ and the outcome whose occurrence it had previously signaled did not impair the ability of that S+ to elicit its original response. In Experiment 3, the response-evoking properties of an S+ were found to be undermined by using the S+ as a signal for the simple extinction of a new response trained with the same outcome, but not with a different outcome. These results suggest that positive discriminative stimuli use their associations with the outcomes earned in their presence to control the responses that earned those outcomes. 相似文献
17.
David R. Thomas C. F. Hickis Raymond L. Jackson Robert J. Newlin 《Learning & behavior》1979,7(3):301-308
In Experiment 1, two groups (n = 10) of pigeons received 17 sessions of TD (true discrimination) or ND (nondifferential) training with line angles. Seventeen sessions of SS (single stimulus) training with a wavelength preceded this training and two followed it. Subsequent wavelength generalization testing in extinction revealed a sharper TD than ND gradient. This slope difference was evident from the very first test stimulus presentation and remained stable throughout testing. As a consequence of substantial overtraining, there was no reduction of response strength and no sharpening of generalization during testing for either group. In Experiment 2, two groups (n = 16) of pigeons received 10 sessions of TD or PD (pseudodiscrimination) training with line angles, followed by four sessions of SS training with a single wavelength. During this training and in subsequent wavelength generalization testing in extinction, brief blackouts separated stimulus presentations. Again, the TD group yielded the sharper gradient. Although responding weakened and the gradients sharpened during the test, these effects were comparable in the two groups. Furthermore, gradients based on the percentage of trials with at least one response showed the same TD-PD slope difference. This finding indicates that differential control over responding by response-produced feedback is inadequate to account for the TD-PD difference in generalization slope. Both experiments indicate that a purported difference in resistance to extinction is also an inadequate explanation. 相似文献
18.
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
19.
Sample and comparison location as factors in matching acquisition,transfer, and acquired equivalence
Urcuioli PJ 《Learning & behavior》2007,35(4):252-261
Pigeons learned symbolic matching with samples appearing equally often on left and right keys. For a location-relevant group,
the reinforced comparison choice for each sample reversed across sample locations; for a location-irrelevant group, the reinforced
choices were the same. Consistent with the hypothesis that samples at different locations are functionally different for pigeons,
Experiment 1 showed that matching acquisition was comparable in these two groups. Nevertheless, the location-irrelevant group
eventually ignored sample location, given that their performances subsequently transferred to a novel (center-key) sample
location. This transfer was not simply due to sample familiarity at different training locations; rather, it required that
left- and right-key samples occasion the same reinforced choices in training. Acquired equivalence between those samples was
then assessed in Experiment 2. The location-irrelevant group showed the predicted equivalence effects, but the location-relevant
group did not—in fact, its results were the opposite of those predicted by equivalence. Their results indicate that the functional
comparison stimuli are also defined in terms of their locations. 相似文献
20.
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