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1.
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
2.
Joint presentations of a conditioned stimulus (CS) and an unconditioned stimulus (US) strengthen the contingency between them, whereas presentations of one stimulus without the other degrade this contingency. For example, the CS can be presented without the US either before conditioning (CS–no US and then CS–US; latent inhibition) or after conditioning (CS–US and then CS–no US; extinction). In vertebrate subjects and several invertebrate species, a time lapse usually results in a return of the conditioned response, or spontaneous recovery. However, in land mollusks, spontaneous recovery from extinction has only recently been reported, and response recovery after latent inhibition has not been reported. In two experiments, using conditioned aversion to a food odor as a measure of learning and memory retention, we observed contingency degradation via latent inhibition (Experiment 1) and extinction (Experiment 2) in the common garden slug, Lehmannia valentiana. In both situations, the contingency degradation procedure successfully attenuated conditioned responding, and delaying testing by several days resulted in recovery of the conditioned response. This suggests that the CS–US association survived the degradation manipulation and was retained over an interval of several days. 相似文献
3.
In a series of related experiments, we studied associative phenomena in snails (Helix aspersa), using the conditioning procedure of tentacle lowering. Experiments 1A and 1B demonstrated a basic conditioning effect in
which the pairing of an odor (apple) as the conditioned stimulus (CS) with the opportunity to feed on carrot as the unconditioned
stimulus (US) made snails exhibit increased levels of tentacle lowering in the presence of the CS. Experiments 2 and 3 showed
that the magnitude of the conditioning was reduced when snails were exposed to the CS prior to the conditioning trial (a latent
inhibition effect). Experiment 4 examined the effects produced by pairing a compound CS (apple—pear) with food presentations
and demonstrated the existence of an overshadowing effect between the two odors. Experiment 5 revealed that pairing one CS
with another previously conditioned stimulus increased tentacle lowering to the new CS (a second-order conditioning effect).
Finally, Experiment 6 showed that pairing two odors prior to conditioning of one of them promoted an increase in tentacle
lowering in response to the other (a sensory preconditioning effect). The results are discussed in terms of an associative
analysis of conditioning and its implications for the study of cognition in invertebrates. 相似文献
4.
Ontogenetic differences in processing light-tone compounds were discovered in preweanling (17-day-old) and adult (60–80-day-old) rats. Suppression of general activity was used as an index of the magnitude of conditioned fear following a single training session in which a CS+ was paired with mild footshock. In Experiment 1, rats were trained on discriminations in which the CS? consisted of a light and the CS+ was either a tone alone (simple discrimination) or a light-tone compound (simultaneous feature-positive discrimination). Adults and preweanlings given each type of discrimination were then tested for fear of the CS? and a target stimulus (tone alone or light-tone compound). Adults in all groups displayed greater fear of the target than of the CS?. Preweanlings, however, discriminated the CS? from the target only when the target was the same as the original CS+. Experiment 2 revealed that age-related differences in conventional stimulus generalization is not a likely explanation for the pattern of results found in Experiment 1. Experiment 3 revealed age-related differences in expressed fear of a serial feature-positive discrimination; adults, but not preweanlings, showed greater fear of the compound than of the CS?. Alternative interpretations of the results from these experiments are discussed, and the general conclusion is that adults appear more inclined to process elements of a compound stimulus selectively, whereas preweanlings seem more likely to process the compound unselectively, with roughly equivalent processing of each element. 相似文献
5.
In four experiments, we examined how the spatiotemporal proximity to food of the two elements of a serial conditioned stimulus (CS) influenced the pattern of CS-directed versus food-site-directed behavior in rats. Experiment 1 showed that only temporal proximity affected responding when the serial CS consisted of two successive 4-sec presentations of either a spatially near or a spatially far lever (NN or FF). However, Experiment 2 showed that behavior depended markedly on whether rats received a near followed by a far lever (NF) or a far followed by a near lever (FN). Experiment 3 showed that the effects of Experiment 2 could be changed by increasing the duration of the second CS element, and Experiment 4 showed that these changes were not related to previous training. We concluded that behavior produced by the spatiotemporal qualities of the lever elements can be attributed to a mapping between the temporal qualities of the CS elements and an underlying sequence of search modes related to finding food. 相似文献
6.
When the conditioned stimulus (CS) is located some distance from the unconditioned stimulus (US), pairings of the CS and US can yield either conditioned approach to the CS (sign tracking) or conditioned approach to the US (goal tracking). However, goal tracking is the more common outcome, and, because of that, goal tracking has come to serve as a “standard” measure of associative learning in several laboratories. In contrast, in previous studies of sexual conditioning with domesticated quail, only sign tracking was observed. In the present study, quail continued to show sign tracking rather than goal tracking whether or not the US was highly localized (Experiment 1), whether food or a sexual US was used (Experiment 2), whether the CS was mobile or immobile (Experiment 3), and whether the CS was 91 or 233 cm from the US compartment (Experiment 4). The present findings encourage caution in the routine use of goal tracking as a measure of learning. The possible mechanisms of goal tracking are discussed in terms of occasion setting and behavior systems theory. 相似文献
7.
Three experiments, using rats, demonstrated the encoding of a food unconditioned stimulus (US) in a simple Pavlovian conditioning paradigm. In all three studies, one stimulus was used to signal the delivery of pellets and a different stimulus was used to signal the delivery of sucrose. In Experiment 1, postconditioning devaluation of one of the food USs selectively reduced the frequency of conditioned magazine-directed behavior during the stimulus trained with that US. In Experiment 2, transfer of the stimuli to instrumental responses resulted in selective depression of the response trained with a different outcome. In Experiment 3, acquisition of stimulus-outcome learning was impaired by unsignaled intertrial presentations of the same outcome but not of a different outcome. These results indicate that a detailed representation of the outcome is encoded in the normal course of Pavlovian conditioning. 相似文献
8.
Sexual responses were conditioned in male Japanese quail using the opportunity to copulate with a female as the unconditioned stimulus (US). The conditioned stimulus (CS) was a 3-D object made of a taxidermically prepared female quail head mounted on a terry-cloth body. Both appetitive conditioned responses (approach and proximity to the CS) and consummatory conditioned responses (mount and cloacal contact directed toward the CS) developed when 2-min presentations of the CS were followed immediately by the US, but not when the CS and US were separated by trace intervals of 10 or 20 min (Experiment 1). Postconditioning sexual satiation suppressed conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 2), and “acute” extinction suppressed both conditioned mounting and conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 3). These results demonstrate a functional dissociation between conditioned appetitive and consummatory responses and imply that the motivational and/or associative mechanisms underlying the two types of behavior are distinct. 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.
Previous place conditioning studies in mice have shown that injection of ethanol immediately before a conditioned stimulus (CS+) produces conditioned preference, whereas injection of ethanol immediately after CS+ produces conditioned aversion. In the present experiments, we examined the learning that occurs when ethanol is injected in “ambiguous“ procedures that provide the opportunity for both types of conditioning. When ethanol was given midway through the CS (Experiments 1 and 2) or both before and after the CS (Experiment 3), the direction of place conditioning was the same as when mice were exposed only to whichever contingency occurred first (a primacy effect). That is, injection of ethanol in the middle of the CS conditioned aversion, whereas injection both before and after the CS conditioned preference. Because these results support the idea that ethanol elicits both aversive and rewarding effects, they are most consistent with conditioning theories that conceptualize unconditioned stimuli (USs) as events that can activate multiple representational components. 相似文献
11.
An attentional-associative model (Schmajuk, Lam, & Gray Journal of Experimental Psychology: Animal Behavior Processes, 22, 321–349, 1996) assumes that nonreinforced presentations of an inhibitory conditioned stimulus (CS) do not decrease its inhibitory associations.
However, the model predicts that extended presentations will decrease attention to the inhibitor, thereby decreasing both
(1) the expression of its inhibitory power in a summation test and (2) the rate of acquisition in a retardation test. The
model also predicts that subsequent presentations of the inhibitory CS with a novel CS will increase both (1) and (2). Using
a predictive learning design in humans, Experiment 1 examined the predictions involving the summation tests, whereas Experiments 2 and 3 examined the predictions involving the retardation tests. Experimental results were in agreement with the predictions of
the model. 相似文献
12.
In two experiments, the influence of exposure to a CS? on the acquisition and retention of a conditioned odor aversion was examined. Preweanling rats were given exposure to the CS? either prior to (CS?/CS+) or following (CS + /CS?) the pairing of a second odor (the CS+) with footshock. The results of Experiment 1 indicated that subjects in both of the treatment conditions acquired aversions of comparable strength to the odor paired with footshock and that retention of the odor aversion was not affected by order of stimulus presentation during conditioning. Experiment 2 indicated, however, that the effectiveness of pretest exposure to various elements of the conditioning episode in reactivation of the memory for conditioningwas dependent on the order of stimulus presentation during conditioning. This differential effectiveness of the various reactivation treatments is discussed in terms of their relationship to the associative “status” of the stimuli present during conditioning and in terms of the information provided to the animal by the reactivation treatment. 相似文献
13.
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
14.
William Timberlake 《Learning & behavior》1986,14(3):276-286
The present experiments explored the relation between a mode of behavior produced by unpredicted presentations of an unconditioned stimulus (US) and subsequent interference with responding to a conditioned stimulus (CS) (the context-blocking effect). The US was food, the CS was a moving ball bearing, and the subjects were rats. The typical response to a moving bearing that predicts food is predatory interaction, and the behaviors that developed under unpredicted US presentations involved focused search and waiting oriented to the food tray. Experiment 1 manipulated the number of unpredicted food presentations and showed that the reduction in subsequent bearing contacts was more clearly related to the occurrence of initial food-tray behavior than to the number of prior food presentations. Experiments 2 and 3 manipulated the conditioning of food-tray behavior while holding constant the number of prior food presentations, and again showed a strong inverse relationship between initial food-tray behavior and ball-bearing contact. The latter experiments also indicated that the locus of interference with bearing-directed behavior was neither primarily central (associative or attentional) nor peripheral (motor interference), but resulted from the incompatibility of two modes of food-getting behavior, a more general predatory search mode versus a mode of focal search and waiting. A behavior-system account of these results does not preclude an associative basis for context-blocking effects, but it argues that such effects may occur at several levels and must function within appetitive structures underlying the animal’s food-getting behavior. 相似文献
15.
The similarity in the discrimination training leading to behavioral contrast and that preceding tests producing response enhancement to combined discriminative stimuli suggested that the two phenomena might be related. This was investigated by determining if contrast indiscrimination training was necessary for this outcome of stimulus compounding. Responding to tone, light, and to the simultaneous absence of tone and light (T + L) was maintained during baseline training by food reinforcement in Experiment I and by shock avoidance in Experiment II. During subsequent discrimination training, responding was reduced in T + L by programming nonreinforcement in Experiment I and safety or response-punishment in Experiment II. In the first experiment, one rat exhibited positive behavioral contrast, i.e., tone and light rates increased while his T + L rate decreased. In Experiment II, rats punished in T + L showed contrast in tone and light, this being the first demonstration of punishment contrast on an avoidance baseline with rats. The discrimination acquisition data are discussed in the light of current explanations of contrast by Gamzu and Schwartz (1973) and Terrace (1972). During stimulus compounding tests, all subjects in both experiments emitted more responses to tone-plus-light than to tone or light (additive summation). An analysis of the terminal training baselines suggests that the factors producing these test results seem unrelated to whether or not contrast occurred during discrimination training. It was concluded that the stimulus compounding test reveals the operation of the terminal baseline response associations and reinforcement associations conditioned on these multicomponent free-operant schedules of reinforcement.
相似文献16.
In two experiments with rat subjects, we examined the effects of a retention interval on performance in two conditioning paradigms in which a conditioned stimulus (CS) was associated with different unconditioned stimuli (USs) in successive phases of the experiment- Experiment 1 was designed to examine aversive-appetitive transfer, in which the CS is associated with shock and then food; Experiment 2 was designed to examine appetitive-aversive transfer, in which the CS is associated with food and then shock. Aversive and appetitive conditioned responses (freezing and head-jerk responding, respectively) were scored from videotape. In both experiments, a 28-day retention interval following the end of Phase 2 caused a recovery of the Phase 1 response and a resuppression of the Phase 2 response. The results suggest that the original association is not destroyed when the CS is associated with a new US in Phase 2. They also suggest that both retroactive and proactive interference effects may result-from interference with performance output rather than a disruption or loss of what is learned during or stored from the target phase. 相似文献
17.
Two experiments are described, which involved the investigation of interactions between the nature of the conditioned stimulus (CS) and the nature of the unconditioned stimulus (UCS) in producing signal-centered behavior. In Experiment 1, rats received response-independent heat reinforcement in a cold environment. For some groups, this heat UCS was signaled by presentations of a standard aluminum retractable lever; for other groups, it was signaled by a retractable lever covered in acrylic fur (furry lever CS). Only the subjects that received the furry lever CS paired with heat exhibited differential CS-contact behavior, when compared with unpaired, aluminum lever, and warm control subjects. In Experiment 2, hungry rats received pairings of either an aluminum or a furry lever with food (UCS). When compared with unpaired controls, only the subjects that received the aluminum lever paired with food showed differential signal-directed behavior; the subjects receiving the furry lever CS did not show differential contact with the CS, but instead exhibited differential food tray entry behavior during CS presentation. In the two studies, the signal-directed behavior exhibited by subjects resembled either thermoregulatory or feeding behaviors characteristic of rats. The results suggest that signal-directed behavior is determined by a complex interaction between the ecological relevance of the CS and the nature of the UCS—an interaction that can best be described in terms of a behavior systems model of conditioned responding. 相似文献
18.
In three experiments that used appetitive preparations with rats, we examined the effects of reinforcing a compound consisting of two previously reinforced stimuli on subsequent responding to those stimuli. Experiment 1 showed that a Pavlovian conditioned stimulus given this treatment evoked fewer magazine entries when presented alone than did a reinforced stimulus that did not receive the compound treatment. Experiment 2 examined inhibition of delay and generalization decrement accounts for the results of Experiment 1. Experiment 3 extended this finding to an instrumental learning paradigm. 相似文献
19.
Four experiments examined the effects of separate presentations of shock on conditioned suppression of instrumental responding evoked by a CS previously paired with shock. Experiment 1 showed that conditioned suppression of responding resulting from noise-shock pairings increased as a function of time after the initial noise-shock pairings. However, it also showed that this time-dependent increase in conditioned suppression of responding could be attenuated by presentations of light-shock pairings immediately prior to the test of the noise CS. Experiment 2 showed that this attenuation effect can be produced by presentations of either light-shock pairings or shock alone. Experiment 3 showed that the magnitude of this attenuation effect was directly related to the temporal proximity of the light-shock pairings to the test of the noise CS. Experiment 4 showed that the magnitude of this attenuation effect was inversely related to the intensity of separate shock presentations. 相似文献
20.
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