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1.
In four experiments utilizing an appetitive conditioning preparation, reacquisition of conditioned responding was found to occur both rapidly and slowly following extinction. In Experiment 1, acquisition of responding to a tone that had been conditioned and extinguished occurred more rapidly than acquisition in either a group that received equivalent exposure to the food unconditioned stimulus or a “rest” control group that received only exposure to the apparatus in the first two phases. However, reacquisition was impaired relative to acquisition in a “learning-experienced” group that had previously received conditioning and extinction with a different stimulus. Experiments 2 and 3 produced similar results, but also found that high responding during reacquisition was confined to trials that followed reinforced, rather than nonreinforced, trials. Experiment 4, in which very few initial conditioning trials were used, produced reacquisition that was slow compared with both learning-experienced and rest controls. The results are consistent with a role for sequential learning: Reacquisition is rapid when animals have learned that reinforced trials signal other reinforced trials. 相似文献
2.
In the present experiments, savings phenomena following a limited amount of initial acquisition and extended extinction were
examined. Experiments 1 and 2 compared rates of reacquisition following brief acquisition and various amounts of extinction
in conditioning of the rabbit’s nictitating membrane and heart rate response, respectively. Experiment 3 compared rates of
acquisition to a novel stimulus (e.g., light) following brief acquisition and various amounts of extinction to another stimulus
(e.g., tone). In addition, in Experiment 3 recovery of responding to the extinguished stimulus during acquisition to the novel,
cross-modal stimulus was examined. Experiments 1, 2, and 3 demonstrated that with a limited number of acquisition trials (1)
there was a graded reduction in the rate of reacquisition as a function of the number of extinction trials in both conditioning
preparations, (2) there was a graded reduction in the rate of cross-modal acquisition as a function of the number of extinction
trials, but (3), in Experiment 3, recovery of responding to the extinguished stimulus during cross-modal training of the novel
stimulus appeared uniformly robust even in the face of extended extinction. 相似文献
3.
Anthony Dickinson 《Learning & behavior》1976,4(4):416-420
In Experiment 1, four groups of rats received conditioned suppression training in which a tone was reinforced with shock. If the tone had been previously paired with response-independent food, aversive conditioning was slightly facilitated by comparison to control groups preexposed either to the tone randomly associated with food or to the tone and food unpaired. However, by comparison to a control which was not preexposed to the tone, animals receiving prior pairings of the tone and food showed retarded aversive conditioning. Experiment 2 replicated the facilitation in aversive conditioning after the tone had been paired with food relative to the random control condition and demonstrated that this difference occurred even if the tone and background stimuli continued to be associated with response-independent food during aversive conditioning. This result suggests that pairing a stimulus with an appetitive reinforcer reduces the retardation of aversive conditioning produced by stimulus preexposure. 相似文献
4.
Four experiments used a within-subjects design with rats to study the effects of preexposure on the restoration of fear responses
(freezing) to an extinguished conditioned stimulus (CS). In each experiment, rats were preexposed to one CS (A), but not to
another (B), and then were exposed to pairings of each of these CSs with an aversive unconditioned stimulus (US). In each
experiment, there was less freezing to A than to B across extinction, showing a latent inhibitory effect of preexposure. There
was no differential recovery to A and B following either a US reexposure (Experiment 1) or a delay interval (Experiment 2). However, when a delay interval included US reexposure, there was greater recovery to the preexposed CS, A, than to the
nonpreexposed CS, B (Experiments 1, 3, and 4). These results suggest that the effects of US reexposure and delay combine to affect recovery from the depressive effects
of CS-alone exposure. The results are consistent with the view that US reexposure produces better mediated conditioning of
CSs that are strongly associated with the context. The results may additionally reflect an effect of preexposure on the learning
produced by extinction. 相似文献
5.
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
6.
Pavlov (1927/1960) reported that following the conditioning of several stimuli, extinction of one conditioned stimulus (CS) attenuated responding
to others that had not undergone direct extinction. However, this secondary extinction effect has not been widely replicated in the contemporary literature. In three conditioned suppression experiments with rats,
we further explored the phenomenon. In Experiment 1, we asked whether secondary extinction is more likely to occur with target
CSs that have themselves undergone some prior extinction. A robust secondary extinction effect was obtained with a nonextinguished
target CS. Experiment 2 showed that extinction of one CS was sufficient to reduce renewal of a second CS when it was tested
in a neutral (nonextinction) context. In Experiment 3, secondary extinction was observed in groups that initially received
intermixed conditioning trials with the target and nontarget CSs, but not in groups that received conditioning of the two
CSs in separate sessions. The results are consistent with the hypothesis that CSs must be associated with a common temporal
context during conditioning for secondary extinction to occur. 相似文献
7.
In three experiments with rats, we demonstrated that a conditioned response that is learned and extinguished in one context (Context A) can be renewed when the conditioned stimulus (CS) is tested in a second context (Context B). In Experiments 1 and 3, the effect was observed in conditioned suppression; in Experiment 2, it was produced in appetitive conditioning. The result occurs when Contexts A and B are equally familiar, equally associated with reinforcement, or equally associated with both reinforcement and nonreinforcement. The results extend the range of conditions known to produce the renewal effect, and they are consistent with the view that retrieval of extinction depends more on the context than does retrieval of conditioning. 相似文献
8.
Three experiments demonstrated that, following the extinction of an established conditioned stimulus (CSA—e.g., tone), the
pairing of a novel, cross-modal stimulus (CSB—e.g., light) with the unconditioned stimulus (US) results in strong recovery
of responding to the extinguished CSA. Experiment 1 demonstrated that the recovery of responding to CSA is not the result
of US reinstatement but is attributable to pairings of CSB with the US. Experiment 2 demonstrated that the recovery of responding
is specific to CSA and is not the result of cross-modal generalization. Experiment 3 revealed that a large number of CSB-US
pairings in Stage 1 significantly reduced the amount of recovery to CSA during subsequent CSB-US trials. Experiment 3 also
provided unexpected evidence of cross-modal secondary extinction. The extinction and subsequent recovery of responding seen
in the present experiments is discussed with respect to possible contributions from contextual associations, CS processing,
US processing, conditioned response expression, and layered excitatory associations. 相似文献
9.
Todd R. Schachtman Wesley J. Kasprow Robert C. Meyer Mark J. Bourne Julie A. Hart 《Learning & behavior》1992,20(3):207-218
Using a conditioned taste aversion preparation overshadowing of flavor-illness association was produced through the presentation of a second flavor during the interval between the first flavor and illness. The modulatory effects of extinguishing the association between the second (over-shadowing) flavor and illness on conditioned responding to the target flavor was investigated. In Experiment 1, we found that, following one-trial overshadowing, extinction of the overshadowing flavor had no effect on conditioned responding to the target flavor. In Experiment 2, we found a similar absence of an effect of extinction of the overshadowing stimulus in a multitrial over-shadowing paradigm. Experiment 3 confirmed the results of Experiments 1 and 2 using conditioning parameters that were designed to weaken the association between the overshadowed flavor and illness. In Experiments 4 and 5, we used simultaneous presentation of the flavors during conditioning and obtained a weakened aversion to the overshadowed flavor when the overshadowing CS was extinguished. These findings are inconsistent with previous observations in conditioned fear preparations that suggest that extinction of the association between the overshadowing stimulus and the unconditioned stimulus attenuates overshadowing. Possible reasons for the discrepant results are discussed. 相似文献
10.
Conditioned suppression in rats is often unaffected when the context (or set of background stimuli) is changed following conditioning. This suggests that responding to the conditioned stimulus (CS) can be relatively insensitive to the context in which the CS is presented. In two experiments, we examined whether sensitivity to contextual stimuli is affected by preexposure to the CS. In Experiment 1, when the CS was novel at the outset of conditioning, conditioned suppression was not affected when the context was changed following conditioning. However, when the CS had been preexposed, responding was weaker when extinction occurred outside of the conditioning context. In Experiment 2, responding was again sensitive to the test context, regardless of whether preexposure occurred in the conditioning context or in an alternate context. These results suggest that the extent to which responding is sensitive to context can depend on the conditioning history of the CS. 相似文献
11.
Water-deprived rats were used to investigate the effects of training a CS in more than one context on conditioned lick suppression. In each experiment, partial reinforcement of the CS was intermingled with unsignaled presentations of the US. In Experiment 1, subjects were either trained in one context alone, trained consecutively in two contexts (such that all training in one context occurred prior to any training in the second context), or trained alternately in two contexts. Following training, the first context, the second context, or neither context was extinguished. Testing of the CS occurred in a third (neutral) context. To the extent that either training context became established as a comparator stimulus for the CS, the comparator hypothesis (Miller & Matzel, 1988) predicts an increase in excitatory responding to the CS following extinction of that context. Subjects trained in a single context exhibited appreciable fear of the CS only when the CS’s training context had been extinguished. Additionally, subjects trained consecutively in the two contexts showed increased fear of the CS following extinction of the second, but not the first training context (i.e., a recency effect). Subjects trained alternately in the two contexts showed no increased fear of the CS as a result of either context alone being extinguished. In Experiment 2, subjects trained alternately in two contexts showed increased fear of the CS only when both training contexts were extinguished, suggesting that both training contexts had become comparator stimuli. These data indicate that multiple training contexts can either compete or act synergistic-ally in modulating responding to a Pavlovian trained CS as a function of the order of training in the different contexts. 相似文献
12.
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
13.
Stimuli that predict the occurrence of aversive events come to elicit conditioned analgesia. Experiments 1A and 1B examined the possibility that conditioning can inhibit analgesia when stimuli are paired in a backward fashion with a shock US (Pavlovian CS- s). Analgesia conditioned in response to shock context exposure was reversed during the CS- (light) presentation after four sessions. The ability of the CS- to function as a conditioned inhibitor of analgesia was then evaluated in both summation (Experiment 1A) and retardation-of-acquisition testing (Experiments 1A and 1B). The results support the conclusion that a stimulus presented after shock in a backward fashion comes to be a conditioned inhibitor of analgesia. Experiments 2A and 2B examined the assumption that the results obtained with our pain sensitivity measure (tailflicking in response to radiant heat) reflect changes in responsiveness to painful input, rather than a general motor inhibition or general insensitivity to sensory input. In Experiment 2A, tailflick responding to painful and nonpainful input was compared in animals receiving either morphine or saline. In Experiment 2B, tailflick responding to painful and nonpainful input to the tail was compared in both the shock and a neutral context. In both experiments, only the painful input yielded changes in responsivity. The results support the conclusion that the alterations in pain sensitivity produced by the CS- for shock represents a conditioned inhibition specific to pain. 相似文献
14.
In three experiments with rat subjects, we examined the effects of trial spacing in appetitive conditioning. Previous research
in this preparation suggests that self-generated priming of the conditional stimulus (CS) and/or unconditional stimulus (US)
in short-term memory is a cause of the trial-spacing effect that occurs with intertrial intervals (ITIs) of less than 240
sec. Experiment 1 nonetheless showed that a trial-spacing effect still occurs when ITIs are increased beyond 240 sec, and
that the effect of ITI over 60–1,920 sec on conditioned responding is best described as a linear function. In Experiment 2,
some subjects were removed from the context during the ITIs, preventing extinction of the context. Removal abolished the advantage
of the long ITI, suggesting the importance of exposure to the context during the long ITI. Experiment 3 still produced a trial-spacing
effect in a within-subjects design that controlled for the level of context conditioning and reinforcement rate in the absence
of the CS. Overall, the results are most consistent with the idea that adding time to the ITI above 240 sec facilitates conditioning
by extinguishing context-CS associations—and possibly context-US associations—that otherwise interfere with CS-US learning
through retrieval-generated priming (see, e.g., Wagner, 1981). 相似文献
15.
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
16.
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
17.
D. A. Powell Charles M. Gibbs Brian Maxwell Dianne Levine-bryce 《Learning & behavior》1993,21(4):303-313
To determine whether the magnitude of heart rate (HR) slowing induced by classical conditioning contingencies is comparable under a broad range of stimulus conditions, experiments were conducted in which rabbits were exposed to tones, increases in illumination, or vibratory stimuli as conditioned stimuli (CSs) and in which paraorbital electric shocks, corneal airpuffs, or intraoral pulses of water served as unconditioned stimuli (USs). The results indicated that conditioned bradycardia was elicited by all three CSs. Moreover, when a corneal airpuff served as the US, small but reliable CS-evoked HR decelerations also occurred. Finally, CS-evoked HR slowing also occurred in response to a tone CS employed in an appetitive task, in which water was the US. These findings suggest that HR slowing is a general phenomenon that occurs when rabbits are exposed to signals that systematically predict aversive or appetitive consequences according to a Pavlovian conditioning paradigm. 相似文献
18.
In two experiments, the marine molluskHermissenda crassicornis was exposed to context discrimination training. In one context, defined by the presence of a diffuse chemosensory stimulus (shellfish extract A), brief, unsignaled, unconditioned stimuli (USs; high-speed rotation) were presented; in a second context, defined by the presence of shellfish extract B, no USs were presented. Animals were then tested (at both 1.5 and 24 h) by exposing them to small pieces of the shellfish meat used to define the two contexts. The latency to strike at the meat served as an index of the context-US association. In Experiment 1, the latency to strike at the cue associated with rotation was reduced relative to both preconditioning strike latencies and the associatively neutral cue. However, in a two-choice test where the animals could approach the conditioned or neutral stimulus, the animals regularly avoided the stimulus paired with rotation. Moreover, if, following conditioning, the animals were presented with an unsignaled rotation in the conditioned context or the neutral context, the animals exhibited more effective defensive clinging (an unconditioned reflex normally elicited by rotation) in the conditioned context, suggesting that it “prepared” the animal for the aversive US. In total, these results demonstrate thatHermissenda is capable of making associations to diffuse background (contextual) stimuli. Moreover, the results suggest that pairing the chemosensory cue with an aversive US elicits a strike response inHermissenda when the animal is placed in forced contact with the cue and an active avoidance response when the animal can choose between that cue and a neutral cue. 相似文献
19.
Rats were used in a lick suppression preparation to assess the contribution of conditioned-stimulus (CS)–context and context–unconditioned-stimulus
(US) associations to experimental extinction. Experiment 1 investigated whether strengthening the CS–acquisition context association enhances extinction by determining whether stronger
extinction is observed when CS-alone trials (i.e., extinction treatment) are administered in the acquisition context (AAC
renewal), relative to a context that is neutral with respect to the US (ABC renewal). Less recovery of responding to the CS
was observed in the former than in the latter case, extending the finding that AAC renewal is weaker than ABC renewal to our
lick suppression preparation. Experiment 2 assessed the contribution of the acquisition context–US association to extinction of a CS by examining the effect of postextinction
exposure to the acquisition context on responding to the extinguished CS. This manipulation enhanced responding to the extinguished
CS in AAC, but not ABC, renewal. Experiment 3 addressed the contribution of the CS–acquisition context association by examining the potential of a neutral stimulus, presented
in compound with the target CS during extinction treatment, to overshadow the CS–acquisition context association. This manipulation
enhanced responding to the extinguished CS in AAC, but not ABC, renewal. The results stress the important role of contextual
association in extinction and renewal. 相似文献
20.
Nicholas J. Grahame Robert C. Barnet Lisa M. Gunther Ralph R. Miller 《Learning & behavior》1994,22(4):395-408
Treatments that attenuate latent inhibition (LI) were examined using conditioned suppression in rats. In Experiment 1, retarded conditioned responding was produced by nonreinforced exposure to the CS prior to the CS-US pairings used to assess retardation (i.e., conventional LI). In Experiment la, retarded conditioned responding was induced by preexposure to pairings of the CS and a weak US prior to retardation-test pairings of the CS with a strong US (i.e., Hall-Pearce [1979] LI). Both types of LI were attenuated by extensive exposure to the training context (i.e., context extinction) following the CS-US pairings of the retardation test. Experiment 2 examined the specificity of the attenuated LI effect observed in Experiment 1. After preexposure to two different CSs in two different contexts, each CS was paired with a US in its respective preexposure context. One of the two contexts was then extinguished. This attenuated LI to a greater degree for the CS that had been trained in the extinguished context. Experiment 3 differentiated the roles in LI of CS-context associations and context-US associations. Following preexposure to the CS in the training context, LI was reduced by further exposure to the CS outside the training context. This observation was interpreted as implicating the CS-context association as a factor in LI. Thus, the results of these experiments suggest that LI is a performance deficit mediated by unusually strong CS-context associations. Implications for Wagner’s (1981) SOP model and Miller and Matzel’s (1988) comparator hypothesis are discussed. 相似文献