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1.
Rats were trained to run up and down an alleyway for sucrose reinforcement on a variable interval schedule. Differential aversive classical conditioning with auditory CSs was then conducted in a separate apparatus (“off the baseline”) prior to those CSs being presented while the subjects were responding for sucrose in the alleyway. Once the effects of the CSs had extinguished, shock was reintroduced following one CS but not the other (“on the baseline” differential aversive classical conditioning). Both “off the baseline” and “on the baseline” conditioning resulted in conditioned suppression to the CS followed by shock, but little effect of the CS followed by no shock was found. In the “on the baseline” phase, total suppression of baseline responding occurred at moderate US intensities, and this appeared to result from the subject avoiding the location at which he was last shocked. At lower values, both baseline response rate and relative suppression ratio were functions of US intensity. The results are discussed in relation to the effects found in similar experiments using avoidance baselines. 相似文献
2.
Three experiments with rat subjects examined the development of simultaneous and serial feature-positive discriminations in appetitive conditioning. In Experiment 1, reinforced presentations of a simultaneous light-tone compound were intermixed with nonreinforced presentations of either the light or the tone. The compound stimulus acquired conditioned behaviors of a form characteristic of the predictive feature alone; the element common to reinforced and nonreinforced trials did not evoke conditioned behavior. In Experiment 2, reinforced presentations of a serial light-trace-tone compound were intermixed with nonreinforced tone-alone presentations. The light feature stimulus acquired conditioned behaviors characteristic of visual CSs. The tone stimulus, common to reinforced and nonreinforced trials, evoked conditioned behaviors characteristic of auditory CSs, but only when preceded by the light. In Experiment 3, variations in the interval between the light and tone on reinforced trials had little effect on responding to the light CS but substantially altered the pattern of responding to the tone CS. These results suggested that simultaneous and serial feature-positive discriminations may be solved differently. Performance in simultaneous feature-positive discriminations may be determined solely by associations between the feature stimulus and the reinforcer, but performance in serial discriminations may also involve the acquisition of a conditional cue function to the feature. 相似文献
3.
Rabbits were trained in eyelid conditioning with a “backward” arrangement of unconditioned stimulus (UCS) followed by conditioned stimulus (CS). When such a CS was tested alone it was observed to produce substantial conditioned responding if the UCS had been arranged to be “surprising” during the backward pairings, but not if it had been arranged to be “expected.” The comparisons were made in a within-subjects design where the surprisingness of the UCS on the different pairing occasions was manipulated by preceding the UCS by discriminative CSs which were otherwise either never followed by the UCS (CS?) or consistently followed by the UCS (CS+). The results may have implications for the nonmonotonic course of responding seen during backward conditioning, as a UCS is at first surprising, but then expected on the basis of contextual cues. 相似文献
4.
The role of temporal factors in the development of conditioned inhibition was investigated in a backward conditioning design. Separate groups of rats received tone CSs either 3 or 30 sec following shock presentations. The CSs predicted the same shock-free interval for both groups. A third group was presented with a random relationship between CS and shock. The CSs were tested by super-imposition on a Sidman avoidance baseline and only the group with a 3-sec UCS-CS interval revealed an inhibitory effect of the CS. These results are in accord with predictions made by the Solomon-Corbit model of acquired motivation and by Denny’s “relaxation” theory of escape and avoidance. 相似文献
5.
Peter C. Holland 《Learning & behavior》1979,7(4):424-432
The form of rats’ Pavlovian conditioned responses to visual and auditory conditioned stimuli (CSs) paired with a variety of unconditioned stimuli (USs) was examined in three experiments using direct behavioral observation techniques. In Experiment 1, the form of conditioned behavior occurring most frequently during later portions of the CS-US interval depended only on which of several appetitive USs was used, but the form of behavior occurring most frequently during early portions of the CS-US interval depended only on the nature of the CS. US-dependent behaviors resembled the response to the US, and CS-dependent behaviors resembled the original orienting response (OR) to the CS. In Experiment 2, the use of larger magnitude appetitive USs resulted in higher frequencies of US-dependent behaviors, but lower frequencies of CS-dependent behaviors in the presence of auditory and visual CSs. In Experiment 3, US-dependent conditioned behavior to auditory and visual CSs paired with shock was more frequent when high-intensity shocks were used, but CS-dependent behavior was more frequent when low-intensity shocks were used. These results suggested that Pavlovian conditioned responding may involve two independent types of behavior—one appropriate to the US and another based on the original OR to the CS. 相似文献
6.
Three experiments examined inhibitory learning in rats, using Pavlovian and differential inhibitory eyeblink conditioning
procedures. Experiment 1 was designed to compare summation and retardation effects following Pavlovian conditioned inhibition
(A1/XA) or differential inhibition (A1/X) training using auditory and visual conditioned stimuli (CSs). After ten 100-trial
sessions of training, both Pavlovian conditioned inhibition and differential inhibition produced a retardation effect. However,
a summation effect was obtained only for rats given Pavlovian conditioned inhibition training. Experiment 2 showed that increasing
differential inhibition training to twenty 100-trial sessions produced summation and retardation effects. In Experiment 3,
rats were trained with either ten or twenty 100-trial sessions of intramodal inhibitory training with two tone CSs (2 kHz
vs. 8 kHz). Summation and retardation effects were obtained after only 20 sessions of differential conditioning. The findings
indicate that extensive training is needed to establish conditioned inhibition with intermodal or intramodal differential
conditioning. 相似文献
7.
Peter C. Holland Judith S. A. Asem Connor P. Galvin Caitlin Hepps Keeney Melanie Hsu Alexandra Miller Vivian Zhou 《Learning & behavior》2014,42(1):1-21
Rats will approach and contact a lever whose insertion into the chamber signals response-independent food delivery. This “autoshaping” or “sign-tracking” phenomenon has recently attracted considerable attention as a platform for studying individual differences in impulsivity, drug sensitization, and other traits associated with vulnerability to drug addiction. Here, we examined two basic stimulus selection phenomena—blocking and overshadowing—in the autoshaped lever pressing of rats. Blocking and overshadowing were decidedly asymmetrical. Previously reinforced lever-extension conditioned stimuli (CSs) completely blocked conditioning to auditory cues (Exps. 1 and 2), and previously nonreinforced lever-extension CSs overshadowed conditioning to auditory cues. By contrast, conditioning to lever-extension CSs was not blocked by either auditory (Exp. 3) or lever-insertion (Exp. 4) cues, and was not overshadowed by auditory cues. Conditioning to a lever-insertion cue was somewhat overshadowed by the presence of another lever, especially in terms of food cup behavior displayed after lever withdrawal. We discuss several frameworks in which the apparent immunity of autoshaped lever pressing to blocking might be understood. Given evidence that different brain systems are engaged when different kinds of cues are paired with food delivery, it is worth considering the possibility that interactions among them in learning and performance may follow different rules. In particular, it is intriguing to speculate that the roles of simple cue–reinforcer contiguity, as well as of individual and aggregate reinforcer prediction errors, may differ across stimulus classes. 相似文献
8.
In Experiment 1, pigeons were trained to discriminate short (2 sec) and long (8 sec) durations of tone by responding to red and green comparison stimuli. During delay testing, a systematic response bias to the comparison stimulus correct for the long duration occurred. Tests of responding without the tone reduced accuracy on long-sample trials but not on short-sample trials suggesting that the pigeons were attending to the tone and not simply timing the total trial duration. The pigeons were then trained to match short (2 sec) and long (8 sec) durations of light to blue/yellow comparisons. During delay testing, “choose-long errors” occurred following tone durations, but “choose-short errors” occurred following light durations. In Experiment 2, accuracy was assessed on test trials in which the tone and the light signals were simultaneously presented for the same duration or for different durations. Pigeons responded accurately to durations of light, but were unable to accurately respond to durations of tone simultaneously presented with the light. The data from Experiment 1 suggest that there are important differences between light and tone signals with respect to the events that control the termination of timing. The data from Experiment 2 indicate that pigeons cannot simultaneously time visual and auditory signals independently and without interference. Consequently, they are inconsistent with the idea that there is a single internal clock that times both tone and light durations. 相似文献
9.
Two experiments attempted to establish vicious-circle behavior through fear motivation combined with secondary punishment. In Experiment 1, rats were trained with two CSs, a tone and a buzzer, paired with shock in different contexts. Secondary punishment based on delay and trace conditioning procedures facilitated running in fear-motivated rats, relative to four control groups. In Experiment 2, rats were given pairings of a tone CS with shock, and a buzzer CS with a drop into a water tank. Fear-motivated rats which received secondary punishment during either 33% or 100% of test trials exhibited self-punitive running relative to a nonpunished (0%) group and a backward-conditioning control group. Results indicate that “all secondary” vicious-circle behavior can be established through Pavlovian conditioning, thus supporting a conditioned fear interpretation. 相似文献
10.
Three experiments with rat subjects examined the effects of contextual stimuli on performance in appetitive conditioning. A 10-sec tone conditioned stimulus (CS) was paired with a food-pellet unconditioned stimulus (US); conditioning was indexed by the observation of headjerking, a response of the rat to auditory stimuli associated with food. In Experiment 1, a context switch following initial conditioning did not affect conditioned responding to the tone; however, when the response was extinguished in the different context, a return to the original conditioning context “renewed” extinguished responding. These results were replicated in Experiments 2 and 3 after equating exposure to the two contexts (Experiment 2) and massing the conditioning and extinction trials (Experiment 3). The results of Experiment 1 also demonstrated that separate exposure to the US following extinction reinstates extinguished responding to the tone; this effect was further shown to depend at least partly on presenting the US in the context in which testing is to occur (Experiments 2 and 3). Overall, the results are consistent with previous data from aversive conditioning procedures. In either appetitive or aversive conditioning, the context may be especially important in affecting performance after extinction. 相似文献
11.
Conditioned lick suppression in rats was used to explore the role of timing in trace conditioning. In Experiment 1, two groups of rats were exposed to pairings of a CS (CS1) with a US, under conditions in which the interstimulus interval (ISI) that separated CS1 offset and US onset was either 0 or 5 sec. Two additional groups were also exposed to the same CS1→US pairings with either a 0 or a 5-sec ISI, and then received “backward” second-order conditioning in which CS1 was immediately followed by a novel CS2 (i.e., CS1→CS2). A trace conditioning deficit was observed in that the CS1 conditioned with the 5-sec gap supported less excitatory responding than the CS1 conditioned with the 0-sec gap. However, CS2 elicited more conditioned responding in the group trained with the 5-sec CS1-US gap than in the group trained with the 0-sec CS1-US gap. Thus, the CS1-US interval had inverse effects on first- and second-order conditioned responding. Experiment 2 was conducted as a sensory preconditioning analogue to Experiment 1. In Experiment 2, rats received the CS1?CS2 pairings prior to the CS1→US pairings (in which CS1 was again conditioned with either a 0 or a 5-sec ISI). Experiment 2 showed a dissociation between first- and second-order conditioned responding similar to that observed in Experiment 1. These outcomes are not compatible with the view that differences in responding to CSs conditioned with different ISIs are mediated exclusively by differences in associative value. The results are discussed in the framework of the temporal coding hypothesis, according to which temporal relationships between events are encoded in elementary associations. 相似文献
12.
Three rats were trained under a discrimination procedure in which responding was reinforced only following the repeated presentation of three bursts of white noise (S+). S? consisted of presentations of either two or four bursts of noise. All animals responded significantly more in the presence of S+ and, in two cases, showed lower response rates to both “2” and “4” stimuli. Responding by the third animal revealed differentiation between S+ and the stimulus “2,” but no reliable suppression to stimulus “4.” The present instances of discriminative control by the stimulus “3” replicate Fernandes and Church’s (1982) demonstration of control by sequential auditory stimuli in the rat. Moreover, because the present procedure involves adjacent S? values both greater as well as less than S+, these results extend our knowledge of the rat’s abilities with sequential auditory stimuli: Rats are capable of making intermediate numerical discriminations based upon something other than a simple many-versus-few dichotomy. 相似文献
13.
In Experiment I, one group of goldfish (TD) was trained to discriminate blue and green while a second group (PD) was exposed to the same colors in a “pseudodiscrimination,” after which both groups were reinforced for response to a tone. The TD group subsequently showed a sharper auditory discrimination gradient than the PD group and performed better in a differentially reinforced tone discrimination. The former PD animals then were given true discrimination training and the former TD animals pseudodiscrimination training with the colors, after which the first group showed better tone discrimination than the second. These results are analogous to those found in pigeons and rats. In Experiment II, goldfish which were trained in an easy color discrimination and shifted to a more difficult tone discrimination performed better than a control group trained from the outset with the tones. This result suggests that the dimensional specificity of the processes responsible for “transfer along a continuum” cannot safely be assumed in the absence of appropriate controls. 相似文献
14.
Rescorla RA 《Learning & behavior》2008,36(2):67-74
Three experiments used a compound test procedure to evaluate whether superior conditioning results from the pairing of stimuli that are related to each other. In each case, a stimulus compound was tested after its component conditioned stimuli (CSs) had been conditioned by the same unconditioned stimuli (USs) arranged such that either related or unrelated CSs and USs were paired. Experiment 1 explored auditory and gustatory stimuli conditioned by LiCl or shock, using rats. Experiments 2 and 3 used second-order conditioning in pigeons to pair stimuli that were similar by virtue either of qualitative features or of shared physical location. In each case, the compound test provided clear evidence that pairing related stimuli produces superior associative learning. 相似文献
15.
In a Pavlovian procedure, groups of pigeons were presented with a compound auditory-visual stimulus that terminated with either response-independent electric shock or food. In a subsequent test, the tone CS was dominant in aversive conditioning, reliably eliciting conditioned head raising and prancing. The red light CS was dominant in appetitive conditioning, reliably eliciting pecking. This result was replicated in a second experiment, in which trials were widely spaced. Pour additional groups of pigeons received pairings of the separate element CSs with the USs. Red light, but not tone, was an effective CS in appetitive conditioning, whereas tone, but not red light, was effective in aversive conditioning. There was no discriminative responding in zero-contingency control groups. Several theoretical accounts of these data are discussed. 相似文献
16.
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
17.
Two studies used a one-trial-a-day aversive conditioning procedure with rats as subjects to investigate the effects of a noise versus a light CS on conditioned freezing. Experiment 1 demonstrated that less conditioned freezing was elicited by the light, although the two CSs led to similar levels of freezing to the contextual cues of the conditioning chamber. Experiment 2 replicated these outcomes and showed that the manipulation of CS intensity produced results similar to those of modality, with the more intense CSs eliciting less freezing. The second experiment also determined that freezing to contextual cues resulted from context conditioning. According to the Rescorla-Wagner model, CSs that condition poorly should generate little competition with context conditioning. Since neither the modality nor intensity factor reliably influenced context conditioning, as measured by context-evoked freezing, the studies provide no support for the view that the effects on CS-evoked freezing represent differences in the strength of conditioning to the various stimuli. This finding raises the possibility that all of the CSs conditioned well but varied in their abilities to elicit freezing because they differed in terms of the form of defensive behavior under their control. 相似文献
18.
Jean S. Hendry 《Learning & behavior》1982,10(4):476-482
The effects of compounding two conditioned stimuli (CSs), each of which had been extinguished to varying degrees in different groups of rats given identical acquisition training, was examined within the conditioned emotional response paradigm. Greater suppression to the compound than to the individual CSs was observed following 6, 12, 48, 72, and 96 stimulus extinction trials, although after only 12 extinction trials suppression to the individual stimuli was no longer observed. The amount of compound suppression decreased progressively as the number of extinction trials increased until, after 120 extinction trials on each stimulus, the compound no longer elicited observable suppression. Control group data indicated that the observed summation effect could not be attributed to disinhibition. The possible role of the summation of undetected excitation in studies examining configurai conditioning, avoidance conditioning and reinstatement is discussed briefly. 相似文献
19.
Three experiments demonstrated that, following the extinction of an established conditioned stimulus (CS; e.g., tone), the
pairing of an orthogonal stimulus from another modality (e.g., light) with the unconditioned stimulus (US) results in strong
recovery of responding to the extinguished CS. This recovery occurred to about an equal degree regardless of whether or not
initial training contained unambiguous stimulus—reinforcer relationships—that is, consistent CS—US pairings—or some degree
of ambiguity, including intramodal discrimination training, partial reinforcement, or even cross-modal discrimination training
(tone vs. light). Experiments 1 and 2 demonstrated that this recovery of responding was largely specific to the extinguished
CS, but moderate generalization to other stimuli from the same modality did appear. The results are discussed with reference
to alternative mechanisms applicable to learning-dependent generalization between otherwise distinct CSs. These models assume
that such generalization is mediated by either a shared response, shared reinforcer, shared context, or shared hidden units
within a layered neural network. A specific layered network is proposed to explain the present results as well as other types
of savings seen previously in conditioning of the rabbit nictitating membrane response. 相似文献
20.
Overshadowing and associability change: Examining the contribution of differential stimulus exposure
In two appetitive conditioning experiments with rats, we investigated the mechanisms responsible for demonstrations of the superior associability of overshadowed conditioned stimuli (CSs) relative to control CSs. In Experiment 1, we investigated whether previous demonstrations were a consequence of differences in the relationship between the CSs and the unconditioned stimulus (US) or of differences in the conditions of exposure to the CSs. Rats received trials with X, Y, and an AB compound, but no delivery of the US (X–, Y–, AB–). A subsequent AY–, AX+, BY + test discrimination revealed that the AY/BY component of the discrimination was solved more readily than the AY/AX component—suggesting the contribution of an exposure effect. In Experiment 2, we better equated the conditions of exposure between A and Y by using AB+, XY+, X– training in Stage 1. In Stage 2, instrumental responses were rewarded during an AY compound. A final test revealed that Y took better control of instrumental responding than did A. The results of these experiments are discussed in terms of classical and contemporary theories of learning and attention. 相似文献