共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
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
3.
Latent inhibition, which refers to attenuated responding to a conditioned stimulus (CS) after CS-unconditioned stimulus (CS-US) pairings as a result of CS-alone presentations prior to the pairings, is often attenuated if preexposure and conditioning occur in different contexts (i.e., it is context specific). Here we report two conditioned lick suppression experiments, using rat subjects, that examined whether manipulations known to attenuate the context specificity of extinction could also eliminate the context specificity of latent inhibition. Context specificity of latent inhibition was eliminated when the CS was preexposed in multiple contexts (Experiment 1) and when the CS was massively pre-exposed in the training context alone (Experiment 2). These results and their practical implications are discussed in the framework of contemporary theories of latent inhibition. 相似文献
4.
Benzodiazepine administration prevents the use of error-correction mechanisms during fear extinction
Genevra Hart Nathan M. Holmes Justin A. Harris R. Frederick Westbrook 《Learning & behavior》2014,42(4):383-397
Three experiments examined the effect of systemic administration of the benzodiazepine midazolam on extinction and re-extinction of conditioned fear. Experiment 1 demonstrated that midazolam administration prior to extinction of a conditioned stimulus (CS) impaired that extinction when rats were subsequently tested drug free; however, extinction was spared if rats were extinguished, reconditioned, and re-extinguished under midazolam. Experiment 2 provided a replication of this effect within-subjects; rats were conditioned to two CSs (A and B), extinguished to one (A-), reconditioned to both, and then extinguished/re-extinguished to both stimuli in compound (AB-), under either vehicle or midazolam. On the drug-free test, rats given midazolam froze more to the CS that had been extinguished (B) than the one that been re-extinguished (A). The final experiment examined whether extinction under midazolam was regulated by prediction error. Rats were trained with three CSs (A, B, C) and extinguished to two (A-, C-). These stimuli then underwent additional extinction under midazolam or vehicle, with one CS now presented in compound with the non-extinguished CS (AB-, C-). Rats were then tested for fear of A relative to C. Rats given vehicle showed a deepening of extinction to A relative to C, as is predicted from error-correction models; however, rats given midazolam failed to show any such discrepancy in responding. The results are interpreted to indicate that the drug reduced prediction error during extinction by reducing fear, and rats were able to re-extinguish fear via a retrieval mechanism that is independent of prediction error. 相似文献
5.
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
6.
“Comparator” accounts of associative conditioning (e.g., Gibbon & Balsam, 1981; Miller & Matzel, 1988) suggest that performance to a Pavlovian CS is determined, by a comparison of the US expectancy of the CS with the US expectancy of general background cues. Recent research indicates that variation in the excitatory value of cues in the local temporal context of a CS may have a profound impact on conditioned responding to the CS (e.g., Kaplan & Hearst, 1982), implicating US expectancy based on local, rather than overall, background cues as the critical comparator term for a CS. In two experiments, an excitatory training context attenuated responding to a target CS. In Experiment 1, the context was made excitatory by interspersing unsignaled USs with target CS-US trials. In this case, posttraining extinction of the conditioning context restored responding to the target CS. In Experiment 2, the target CS’s local context was made excitatory by the placement of excitatory “cover” stimuli in the immediate temporal proximity of each target CS-US trial. In this experiment, posttraining extinction of the proximal cover stimuli, not extinction of the conditioning context alone, restored responding to the target CS. An observation from both experiments was that signaling the otherwise unsignaled USs did not appear to influence the associative value of the conditioning context. The results are discussed in relation to a local context version of the comparator hypothesis and serve to emphasize the importance of local context cues in the modulation of acquired behavior. Taken together with other recent reports (e.g., Cooper, Aronson, Balsam, & Gibbon, 1990; Schachtman & Reilly, 1987), the present observations encourage contemporary comparator theories to reevaluate which aspects of the conditioning situation comprise the CS’s comparator term. 相似文献
7.
In two experiments with rats as subjects, the temporal characteristics of inhibition produced through extinction were investigated.
Each experiment established two independent signals for unconditioned stimulus presentation, one trace and one delay. Following
initial training, either the trace or the delay conditioned stimulus (CS) was massively extinguished. In Experiment 1, a summation
test established that an extinguished delay CS (but not a neutral CS) passed a summation test with a delay, but not with a
trace, transfer excitor, and an extinguished trace CS (but not a neutral CS) passed a summation test with a trace, but not
with a delay, transfer excitor. In Experiment 2, a retardation test showed retarded behavioral control by an extinguished
delay CS when the CS was retrained as a delay CS, but not as a trace CS, and by an extinguished trace CS when the CS was retrained
as a trace CS, but not as a delay CS. The results are discussed in terms of contemporary theories of extinction. 相似文献
8.
Water-deprived rats served in seven conditioned lick suppression experiments designed to assess the effects on responding to a target CS of a series of unsignaled USs given in the training context following completion of CS training. Such treatment has been hypothesized to increase (inflate) the associative strength of the background cues from training (putatively, the CS’s comparator stimuli), thereby reducing responding to excitatory CSs and increasing the inhibitory potential of inhibitory CSs. Although posttraining extinction (deflation) of the CS’s comparator stimuli usually decreases inhibitory potential and increases excitatory potential of the target CS, posttraining inflation of the comparator stimuli had no effect on either excitatory responding to the target CS or summation test performance indicative of conditioned inhibition. This outcome was consistently obtained across a number of training, inflation, and test conditions selected to maximize sensitivity to any possible effects of comparator inflation. Implications of these null results for the comparator hypothesis of conditionedresponse generationare discussed. 相似文献
9.
Extinction-induced attenuation of single-phase and two-phase blocking was examined with rats in a conditioned lick-suppression
task. In Experiment 1, which compared the effectiveness of single- and two-phase blocking, it was found that single-phase
blocking was facilitated by the initiation of training with an A-US trial rather than an AX-US trial. Single-phase (but not
two-phase) blocking was attenuated as a result of 200 extinction trials with the blocking stimulus (Experiment 2). Experiment
3 revealed recovery from two-phase blocking after 800 extinction trials with the blocking stimulus. Recovery from both types
of blocking was specific to the blocked CS trained in compound with the extinguished stimulus (Experiment 4). This is the
first article to report that the blocking deficit can be reversed by extinguishing the blocking stimulus. These results are
discussed in light of acquisition models (i.e., retrospective revaluation) and expression models (i.e., the comparator hypothesis). 相似文献
10.
In Experiment 1, 12 pigeons were given eight sessions of VI single stimulus training with a color in a particular context followed by eight sessions of similar training with a line angle in another context. On the next day, half of the subjects were tested for wavelength and angularity generalization in each of the two contexts, a procedure that was thus consistent with training for one dimension and inconsistent for the other. The subjects made significantly more responses to each training stimulus under the consistent context condition, but there was no difference in absolute or relative generalization slopes. In Experiment 2, 12 pigeons were trained as in Experiment 1, but during generalization testing they were exposed to both contexts sequentially. Under the consistent context condition, the subjects responded more to the two training stimuli and yielded sharper absolute and relative wavelength generalization gradients: Under the inconsistent context condition, responding to the training wavelength was substantially disrupted. Thus, under appropriate testing conditions, contextual control over both the amount and the selectivity of responding can be demonstrated. 相似文献
11.
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
12.
Four experiments were performed to explore the role of context in operant extinction. In all experiments, leverpressing in
rats was first reinforced with food pellets on a variable interval 30-s schedule, then extinguished, and finally tested in
the same and a different physical context. The experiments demonstrated a clear ABA renewal effect, a recovery of extinguished
responding when conditioning, extinction, and testing occurred in contexts A, B, and A, respectively. They also demonstrated
ABC renewal (where conditioning extinction and testing occurred in contexts A, B, and C) and, for the first time in operant
conditioning, AAB renewal (where conditioning, extinction, and testing occurred in contexts A, A, and B). The latter two phenomena
indicate that tests outside the extinction context are sufficient to cause a recovery of extinguished operant behavior and,
thus, that operant extinction, like Pavlovian extinction, is relatively specific to the context in which it is learned. AAB
renewal was not weakened by tripling the amount of extinction training. ABA renewal was stronger than AAB, but not merely
because of context A’s direct association with the reinforcer. 相似文献
13.
Four experiments with rat subjects examined the role of context during the extinction of instrumental (free-operant) behavior. In all experiments, leverpressing was first reinforced on a variable-interval 30-s schedule and then extinguished before being tested in the extinction and renewal contexts. The results identified three important variables affecting the renewal effect after instrumental extinction. First, ABA and ABC forms of renewal were strengthened by increasing the amount of acquisition training. This suggests that the strength of the association learned during acquisition, or the final level of performance, influences the degree of renewal after extinction. The effect of the amount of training was modulated by the second factor, the degrees of generalization from the acquisition and extinction contexts to the test context. The third variable was acquisition training in multiple contexts, which was shown to strengthen ABC renewal. Methodological, theoretical, and practical implications are discussed. 相似文献
14.
In the present experiments, we investigated the effects of mindfulness on behavioral extinction and resurgence. Participants received instrumental training; either they received FI training (Experiment 1), or they were trained to emit high rates and low rates of response via exposure to a multiple VR yoked-VI schedule prior to exposure to a multiple FI FI schedule in order to alter their rates of responding learned during Experiment 2. Participants were then exposed to either a focused- (mindfulness) or an unfocused-attention induction task. All participants were finally exposed to an extinction schedule in order to determine whether a mindfulness induction task presented immediately prior to extinction training affected extinction (Experiment 1) and behavioral resurgence (Experiment 2). During the extinction phase, the rates of responding were higher in the control group than in the mindfulness group, indicating that the mindfulness group was more sensitive to the contingencies and, thus, their prior performance extinguished more readily (Experiment 1). Moreover, rates of response in the extinction components less precisely reflected previous training in the mindfulness group, suggesting less resurgence of past behaviors after the mindfulness induction (Experiment 2). 相似文献
15.
The source of renewal of instrumental responding in rats was investigated. In Experiment 1, two responses (R1 and R2) were reinforced with one outcome (O1) in contexts A and B (i.e., R1→O1, R2→O1), and then R2 was extinguished in A and R1 was extinguished in B. At test, the rate of R1 was higher than that of R2 in context A, and the reverse was the case in context B: Renewed responding was independent of the Pavlovian context→O1 associations. In Experiment 2, all rats received R1→O1 and R2→O2 trials in A and then were placed in B, where they were sated on O2 and either did (Group Extinction) or did not (Group No Extinction) receive concurrent extinction of R1 and R2. At test, we found more responding in A than in B for Group Extinction, but not for Group No Extinction, and the renewed responding in A was as sensitive to the current value of the outcome as responding that had not been subject to extinction (i.e., the rate was higher for R1 than for R2). That is, the renewed responding was goal-directed. These results identify the removal of contextual inhibion of either the response or the response→outcome associaon as potenal bases for renewal, and the response→outcome associaon as the source of renewed responding. 相似文献
16.
Subjects in six experimental groups (n = 16 each) received one-trial passive avoidance (PA) training in which shock was delivered upon movement from a white wooden
floor compartment to a black grid compartment. Then fear was extinguished (30 min) in the black compartment. After either
24 or 168 h, all the groups were treated in a room distinctively different from the training room. At each interval, one group
received a shock in an apparatus similar to the conditioning box, another received a shock in a dissimilar apparatus, and
another was placed in a neutral box. A PA test trial in the training apparatus indicated reinstatement of extinguished fear
in all the groups given a postextinction shock except the 24-h dissimilar group. Control groups revealed that the extinction
treatment was effective and that spontaneous recovery was not evident. The results were explained in terms of classical conditioning,
stimulus generalization, and the broadening (flattening) of stimulus generalization gradients with time. 相似文献
17.
Four conditioned suppression experiments with rats, using an ABC renewal design, investigated the effects of compounding the target conditioned excitor with additional, nontarget conditioned excitors during extinction. Experiment 1 showed stronger extinction, as evidenced by less renewal, when the target excitor was extinguished in compound with a second excitor, relative to when it was extinguished with associatively neutral stimuli. Critically, this deepened extinction effect was attenuated (i.e., more renewal occurred) when a third excitor was added during extinction training. This novel demonstration contradicts the predictions of associative learning models based on total error reduction, but it is explicable in terms of a counteraction effect within the framework of the extended comparator hypothesis. The attenuated deepened extinction effect was replicated in Experiments 2a and 3, which also showed that pretraining consisting of weakening the association between the two additional excitors (Experiments 2a and 2b) or weakening the association between one of the additional excitors and the unconditioned stimulus (Experiment 3) attenuated the counteraction effect, thereby resulting in a decrease in responding to the target excitor. These results suggest that more than simple total error reduction determines responding after extinction. 相似文献
18.
In two experiments, two groups of rats were trained in a navigation task according to either a continuous or a partial schedule
of reinforcement. In Experiment 1, animals that were given continuous reinforcement extinguished the spatial response of approaching
the goal location more readily than animals given partial reinforcement—a partial reinforcement extinction effect. In Experiment
2, after partially or continuously reinforced training, animals were trained in a new task that made use of the same reinforcer
according to a continuous reinforcement schedule. Animals initially given partial reinforcement performed better in the novel
task than did rats initially given continuous reinforcement. These results replicate, in the spatial domain, well-known partial
reinforcement phenomena typically observed in the context of Pavlovian and instrumental conditioning, suggesting that similar
principles govern spatial and associative learning. The results reported support the notion that salience modulation processes
play a key role in determining partial reinforcement effects. 相似文献
19.
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
20.
In 2 infant speech recognition experiments using trisyllabic sequences, the amount of redundancy within nontarget, context syllables was manipulated. Infants 6 1/2 months old were trained to discriminate the syllables [ba] versus [du] in contexts that were either redundant (e.g., [ko ba ko] or [ti ba ti]) or mixed (e.g., [ko ba ti] or [ti ba ko]) A visually reinforced head-turning procedure was employed. In Experiment 1, context was manipulated between subjects, but in Experiment 2 each subject received all 4 contexts (2 redundant, 2 mixed). Infants consistently recognized the familiar target in all contexts, but did so more successfully in redundant than in mixed trisyllablic contexts. These results suggest that amount of speech redundancy may be an important factor in infants' perceptual capabilities. 相似文献