共查询到20条相似文献，搜索用时 46 毫秒
1.
Christopher L. Cunningham Robert D. Fitzgerald David L. Francisco 《Learning & behavior》1977,5(2):135-142
A comparison was made of heart-rate (HR) responses of restrained rats to CSs that were part of an explicitly unpaired or a truly random control procedure. Subsequent to these procedures, an assessment was made of the relative capacities of these CSs to affect an established HR CR in a combined-cue paradigm and to impede the development of a HR CR in a reversal-conditioning situation. The principal findings were (1) that the explicitly unpaired and truly random CSs generated HR responses of opposite direction, i.e., HR acceleration vs. HR deceleration, respectively, and (2) that conditioning of a decelerative HR CR to the CS that had earlier been employed in the explicitly unpaired procedure was retarded compared to what was obtained to the truly random CS. The two CSs did not have reliably different effects in the combined-cue test. It was suggested that the truly random CS may have produced both associative and nonassociative influences on HR. It was hypothesized further than the explicitly unpaired CS may have acquired the capacity to function as a conditioned inhibiting stimulus. 相似文献
2.
Twenty-eight male albino rats were given a single 4-sec 1-mA electric-grid-shock unconditioned stimulus (US). In the same session they received two 12-sec conditioned stimuli (CSs). One CS (explicitly unpaired) terminated 180 sec before the US began; the other (backward paired) began immediately after the US terminated. The CSs used were a 1000-Hz 85-dB tone and an 84-dB click; their roles were counterbalanced. Over the next 2 days, each CS was presented for 2 min while the rats drank from a water bottle. The backward-paired CS was found to suppress licking more than the explicitly unpaired CS. This suppression was accompanied by an increase in defensive behavior (freezing and freeze/nod) and by a decrease in other activity. The suppression did not seem to be due to a maintained or enhanced CS-orienting response reflex, nor could it be attributed to an adventitiously reinforced interfering operant. The results support the presumption made in previous reports that the lick suppression evoked by a backward CS reflected one-trial backward excitatory fear conditioning. 相似文献
3.
Rabbits under high or moderate water deprivation received in Stage 1 either paired (CS+), unpaired (CS?), or no-tone/shock presentations, with the pairings being appropriate for nictitating membrane conditioning. In Stage 2, all groups were given paired tone and water deliveries for jaw-movement conditioning, while, in Stage 3, all group received the tone and shock paired together for membrane conditioning. In Stage 2, the previously established aversive CS+ suppressed jaw-movement conditioning under high deprivation, and membrane CR decrements were directly related to deprivation. Also in Stage 2, the aversive CS? raised jaw-movement conditioning under moderate deprivation. In Stage 3, membrane CR performance immediately returned in the aversive CS+ group. For the other groups, conditioning was faster under high, relative to moderate, deprivation; however, the initial membrane CR occurrence required more trials if unpaired presentations were used in Stage 1. These results suggest that CSs can acquire both opponent-process and associative effects expressed according to the prevailing training conditions. 相似文献
4.
SingleParamecium caudatum were conditioned by pairing ac-generated electric shock (US) with a vibratory stimulus (CS) produced by an auditory speaker. Naive paramecia subjected to shock reliably exhibited a backwards jerk and axial spinning similar to the avoiding reaction described by Jennings in 1904. Such responses did not occur initially to CS alone, but increasingly appeared during the CS period preceding shock pairing (delayed conditioning paradigm). Control subjects given the CS and UCS at the same intervals, but explicitly unpaired, did not show a sustained increase of responses to the CS alone. Short-term memory was demonstrated by subjects first conditioned and then presented CS alone during extinction. These subjects were readily reconditioned. Paramecia trained and stored for 24 h showed reliable memory savings as compared to stored control subjects. Other paramecia were differentially conditioned by training with two CSs. Following the recommendations of Rescorla (1967), a procedure was designed for truly random presentation of the CS and UCS as an additional control for pseudoconditioning. Single paramecia were conditioned with intervals between CSs randomly ranging from 8 to 32 sec. Control subjects received the same number of CSs and UCSs, which were administered independently and randomly during the same total session duration. Thus, CS and UCS were occasionally paired for control subjects. The responses to CS in the conditioned group were anticipatory conditional responses due to the pairing contingency and not wholly due to pseudoconditioning. 相似文献
5.
Three experiments with rat subjects sought to enhance one-trial excitatory simultaneous and backward fear conditioning by using a two-element compound conditioned stimulus (CS) instead of only a single element. During conditioning, experimental groups received a 4-sec CS either coextensively with a 1-mA grid-shock unconditioned stimulus (US) or immediately after US termination. In subsequent tests, CSs evoked more lick suppression and freezing in these groups than in various controls. Compound CSs evoked more lick suppression and freezing than did CS elements, but did so equally for experimental and control groups. Therefore, the use of compounds did not enhance conditioning. Unexpectedly, an explicitly unpaired control in which CS followed US termination by 3 min tended to show more CS-evoked suppression and freezing than did a control in which CS preceded US onset by 3 min. This result raises the possibility that associations between the CS and the training context might engender responding to backward-paired CSs. 相似文献
6.
Jack Edward Sherman 《Learning & behavior》1978,6(4):463-468
Two experiments with rat subjects in a conditioned punishment paradigm are reported. These experiments attempted to determine if the events entering into association with the CS following conditioning with informative (forward) and noninformative (simultaneous) CSs were comparable. In Experiment 1, exposure to intense shock alone following trace (ISI = 10 sec) conditioning with moderate shock enhanced the suppressive effects of a 2-sec CS. A similar manipulation following explicitly unpaired CS-US presentations (ISI = 2 min) had no effect. These data were taken as evidence that the CS and US were associated during trace conditioning. Experiment 2 showed that exposure to intense shock following simultaneous conditioning also enhanced suppression to the CS. These results suggested that simultaneous and forward conditioning procedures yield similar forms of associative learning. 相似文献
7.
Three experiments demonstrated Pavlovian appetitive discrimination learning in the marine mollusc,Aplysia californica. In each experiment, subjects were exposed to two conditioned stimuli; one stimulus (CS+) was paired with food presentations and the other stimulus (CS?) was never followed by food. In Experiments 1 and 3 different chemosensory stimuli were used, and in Experiment 2 different tactile stimuli were used. For both types of conditioned stimuli, bite responses occurred significantly more often to the CS+ than to the CS?. Experiment 2 also showed thatAplysia could learn a reversal of this discrimination. Experiment 3 showed that nonreinforced presentations of CS+ resulted in a decline in the frequency of conditioned biting. The implications of these results for neurobiological analyses of learning are discussed. 相似文献
8.
The present study employed a Pavlovian-instrumental-transfer paradigm to investigate the role of conditioned fear in appetitive discrimination learning. Each of three Pavlovian training procedures was used to establish a conditioned fear excitor (CS+), a “neutral” CS (CSo), and a conditioned fear inhibitor (CS?). Then, the CSs were administered to rats in the three groups contingent upon the rewarded response in a difficult visual discrimination. In addition, half of each group received shock punishment for each incorrect response. Relative to CSo, CS+ facilitated performance in contrast to the usual interfering effect of conditioned suppressors; conversely, CS? retarded performance even when its reinforcing action (fear inhibition) was potentiated by punishment for the incorrect response. These results, together with other findings showing a reversed outcome when the CSs are administered for the incorrect response, indicate that Pavlovian conditioning comprises both general signaling and affective functions, the former reflecting a basic “expectancy” or nominal type of cognitive processing in the rat. 相似文献
9.
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
10.
Dale Swartzentruber 《Learning & behavior》1993,21(1):14-22
Two autoshaping experiments with pigeons examined contextual control of responding to conditioned stimuli (CSs) when separate phases of reinforcement and nonreinforcement occurred in different contexts. In Experiment 1, a CS was first conditioned in Context A prior to nonreinforcement in Context B. In Experiment 2, a conditional discrimination reversal procedure was employed in which one CS was first reinforced in A prior to nonreinforcement in B, and another CS was first nonreinforced in A and then reinforced in B. In both experiments, the extent of contextual control was assessed by testing the CSs in A and B. The CS specificity of control was assessed by examining control of CSs that had been treated like the original CSs, but in a different pair of contexts. The results show that contexts control responding to CSs through a CS-specific mechanism, as well as through a mechanism that is independent of the identity of the CS. However, the extent to which control is mediated by a CS-independent mechanism depends on the training history of the CS. 相似文献
11.
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
12.
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
13.
Two experiments used rats in a conditioned lick suppression preparation to investigate how the conditioned stimulus (CS)-duration
and partial-reinforcement effects (i.e., weakened responding due to conditioning with a CS of longer duration and presenting
nonreinforced CSs intermingled with CS—unconditioned stimulus [US] pairings, respectively) interact with overshadowing. Experiment
1 found that when overshadowing treatment was combined with either extended CS duration or partial reinforcement, the response
deficit was weaker than when either of these three treatments was administered alone. In Experiment 2, the generality of the
findings in Experiment 1 was investigated by replicating it with various US—US intervals. This time counteraction was observed
only when both the absolute duration of total CS exposure and the US—US interval were short. The results support neither the
view that the ratio between the total CS exposure and total time in the context determines the CS-duration and the partial-reinforcement
effects nor the view that these two effects arise from a loss of effectiveness of the excitatory CS—US association during
CS-alone exposures in partial reinforcement or early periods of CS exposure with long CSs. 相似文献
14.
Robert D. Fitzgerald David L. Francisco James Metcalfe Maralee S. Lawson 《Learning & behavior》1984,12(2):217-222
Classical discrimination conditioning of heart rate (HR) and respiratory-motor (RM) activity was examined in 16 newborn (average age = 1 day) and 8 neonatal (average age = 2 weeks) pygmy goats over 4 days of conditioning involving an electric shock US and auditory CSs. On the 4th day, one-half of the animals in each group received a low to moderate dose of ethanol to test the resistance of the CRs to drug effects. Discriminated conditioning of RM activity but not HR occurred in the newborn group, indicating an absence of close coupling between skeletal-motor activity and HR at this early age. While the newborn group failed to show recognizable HR reactions to the CSs during the 4 days of testing, it did show a long-latency brady-cardia UR beginning at 2 days of age that may have been secondary to baroreceptor reflex actions. The neonatal group displayed conditioning of both HR and RM activity. The similar latencies of the two types of CRs during the CS suggested that they may have been related to each other. However, the fact that the RM CR developed a day before the HR CR, combined with the observation that ethanol modified the HR CR but not the RM CR, supports the view that there was considerable independence between the two types of CRs. 相似文献
15.
Barpress suppression in a 1-min interval following CS trials was investigated using 16 rats in a conditioned suppression procedure with a two-stage design. For one group, each CS co-terminated with a brief shock US in Stage 1; then, in Stage 2, only half the CSs ended with a shock, which in turn was followed 1 min later by a second shock. For a second group, the two stages were reversed. When CSs were followed by single shocks in Stage 1, posttrial suppression weakened across trials; but when, in Stage 2, double shocks followed half the CSs, posttrial suppression grew stronger. When half the trials were followed by double shocks in Stage 1, posttrial suppression was maintained at initial levels but weakened in Stage 2 when single shocks followed each trial. In both stages, posttrial suppression was stronger on nonreinforced than on reinforced trials. Two factors were hypothesized to control posttrial suppression. First, posttrial suppression weakens with training under the single-shock procedure because post-shock temporal stimuli come to inhibit fear unless themselves paired with shock. Second, posttrial suppression is stronger on nonreinforced trials than on reinforced trials because freezing behaviors initiated during the CS are not disrupted by a US and so persist into the posttrial interval. 相似文献
16.
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
17.
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
18.
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
19.
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
20.
Water-deprived adult rats were used in a conditioned-suppression-of-licking procedure to determine the effect of inhibitory training with a novel stimulus trained in simultaneous compound with a previously established conditioned inhibitor. This procedure constitutes an inhibitory analogue to the excitatory blocking procedure in classical conditioning. The conditioned-inhibition training consisted of either explicitly unpaired CS and US presentations or negative contingency training, in which the likelihood of the US was greater in the absence than in the presence of the CS, but the CS and the US were occasionally paired. To assess conditioned inhibition, a retardation test was used, and comparable retardation was obtained for subjects that were administered the blocking treatment and control subjects given similar conditioned-inhibition training with a compound stimulus in which the nontarget element was not previously established as a conditioned inhibitor. 相似文献