scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Probability of shock in the presence and absence of CS in fear conditioning.

01 Aug 1968-Journal of Comparative and Physiological Psychology (J Comp Physiol Psychol)-Vol. 66, Iss: 1, pp 1-5
TL;DR: 2 experiments indicate that CS-US contingency is an important determinant of fear conditioning and that presentation of US in the absence of CS interferes with fear conditioning.
Abstract: 2 experiments indicate that CS-US contingency is an important determinant of fear conditioning and that presentation of US in the absence of CS interferes with fear conditioning. In Experiment 1, equal probability of a shock US in the presence and absence of a tone CS produced no CER suppression to CS; the same probability of US given only during CS produced substantial conditioning. In Experiment 2, which explored 4 different probabilities of US in the presence and absence of CS, amount of conditioning was higher the greater the probability of US during CS and was lower the greater the probability of US in the absence of CS; when the 2 probabilities were equal, no conditioning resulted. Two conceptions of Pavlovian conditioning have been distinguished by Rescorla (1967). The first, and more traditional, notion emphasizes the role of the number of pairings of CS and US in the formation of a CR. The second notion suggests that it is the contingency between CS and US which is important. The notion of contingency differs from that of pairing in that it includes not only what events are paired but also what events are not paired. As used here, contingency refers to the relative probability of occurrence of US in the presence of CS as contrasted with its probability in the absence of CS. The contingency notion suggests that, in fact, conditioning only occurs when these probabilities differ; when the probability of US is higher during CS than at other times, excitatory conditioning occurs; when the probability is lower, inhibitory conditioning results. Notice that the probability of a US can be the same in the absence and presence of CS and yet there can be a fair number of CS-US pairings. It is this that makes it possible to assess the relative importance of pairing and contingency in the development of a CR. Several experiments have pointed to the usefulness of the contingency notion. Rescorla (1966) reported a Pavlovian 1This research was supported by Grants MH13415-01 from the National Institute of Mental Health and GB-6493 from the National Science Foundation, as well as by funds from Yale University.

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: The cellular mechanisms that underlie learning and memory formation remain one of the most intriguing unknowns about the mammalian brain and Pavlovian fear conditioning is a good candidate to provide evidence.
Abstract: The cellular mechanisms that underlie learning and memory formation remain one of the most intriguing unknowns about the mammalian brain. A plethora of experimental evidence over the last 30 years has established that long-term synaptic plasticity at excitatory synapses is the most likely mechanism that underlies learning and memory formation. Experiments done largely in acute brain slices maintained in vitro have revealed many of the molecular mechanisms in the induction and maintenance of long-term potentiation (LTP). However, evidence directly liking LTP with learning and memory formation has not been established. Pavlovian fear conditioning is a good candidate to provide such evidence. The relations between events that produce fear conditioning are simple; these relations and their fear products involve circuits in the amygdala that are well understood, as are those circuits in the amygdala that underlie LTP. The evidence that links LTP in the amygdala with fear conditioning is reviewed.

132 citations

Journal ArticleDOI
TL;DR: Results of autoshaping experiments suggest that contextual value does interact with CS-US learning and may also affect performance to the CS.
Abstract: Context-unconditioned-stimulus (US) associations have been suggested as the mediator of the response decrement that occurs when extra USs are added to the intertrial intervals (ITIs) of an otherwise standard Pavlovian conditioning situation. The present autoshaping experiments were concerned with the effect of signaling those extra USs, since such signaling might be expected to lessen their ability to condition the context. Experiments 1 and 2 showed that signaling the ITI USs did reduce their detrimental effects on responding to the conditioned stimulus (CS). To determine whether that reduction was due to an impact of signaling on the target-CS-US association or on performance to the target-CS, Experiment 3 examined responding to differentially trained CSs in a common context, as well as responding to identically trained CSs in differentially trained contexts. Whether the CS was tested in a context of relatively high or low associative strength, more responding occurred to the CS trained with signaled, as compared with unsignaled, ITI USs; further, there was more responding to that CS in the more highly valued context. The pattern of results suggests that contextual value does interact with CS-US learning and may also affect performance to the CS.

130 citations

Journal ArticleDOI
TL;DR: This article outlines and assesses the main theories of the placebo effect and suggests how they might sit together in a larger model of placebo etiology.
Abstract: This article outlines and assesses the main theories of the placebo effect and suggests how they might sit together in a larger model of placebo etiology. Among the approaches considered are expectancy theory, emotional change theory, classical conditioning, and the biological approach. Although these are sometimes assumed to be competing models, in many cases they shed light on different pans of the placebo puzzle. Expectancies are the core of most placebo effects in human beings. The effects of expectancies are sometimes unmediated but in other cases are mediated by changes in emotional state, immune system function, perception, or behavior. Although expectancies are implicated in most placebo effects, a small number of placebo effects may be solely attributable to nonconscious contingency learning.

127 citations


Cites background from "Probability of shock in the presenc..."

  • ...Modern accounts of classical conditioning stress the information value of the CS, in terms of predicting the subsequent occurrence of the US (Kamin, 1968, 1969; Rescorla, 1968, 1988; Rescorla & Wagner, 1972)....

    [...]

  • ...Modern accounts of classical conditioning stress the information value of the CS, in terms of predicting the subsequent occurrence of the US (Kamin, 1968, 1969; Rescorla, 1968, 1988; Rescorla & Wagner, 1972)....

    [...]

Journal ArticleDOI
TL;DR: A revised version of the Moore-Stickney model and a real-time version of Pearce and Hall’s (1980) model, both incorporating the proposed modifications for the effect of hippocampal lesions, were applied to different classical conditioning paradigms and proved capable of simulating most hippocampal lesion effects.
Abstract: Moore and Stickney (1980) described a real-time computational version of Mackintosh’s (1975) attentional model of associative learning. By assuming that hippocampal lesions affect computations that control the rate of learning, they were able to simulate impairments of latent inhibition and blocking, as reported in studies of classical conditioning. Schmajuk (1984a) proposed that hippocampal lesions affect computations of stimulus associabilities, as defined in Pearce and Hall’s (1980) model of learning. A revised version of the Moore-Stickney model and a real-time version of Pearce and Hall’s (1980) model, both incorporating the proposed modifications for the effect of hippocampal lesions, were applied to different classical conditioning paradigms. Simulation experiments with both models were carried out for the following protocols: acquisition under simultaneous, delay, and trace conditioning; partial reinforcement; noncontingent training; conditioned inhibition; differential conditioning; extinction; latent inhibition; blocking; overshadowing; and discrimination reversal. Although some discrepancies between simulation experiments and relevant literature were noted, both models proved capable of simulating most hippocampal lesion effects.

127 citations

Journal ArticleDOI
TL;DR: The siphon withdrawal reflex of Aplysia undergoes differential classical conditioning with cutaneous stimulation of the siphon or mantle shelf as the discriminative conditioned stimuli (CS+ and CS-) and shock to the tail as the unconditioned stimulus (US).
Abstract: he siphon withdrawal reflex of Aplysia undergoes differential classical conditioning with cutaneous stimulation of the siphon or mantle shelf as the discriminative conditioned stimuli (CS+ and CS-) and shock to the tail as the unconditioned stimulus (US). The reflex has proved to be useful for analyzing the neural mechanisms of conditioning. To test the generality of this experimental system, we have begun to compare the properties of conditioning in Aplysia with those of conditioning in vertebrates. We first examined the effect of the interstimulus interval (ISI) by varying the time between presentation of the CS+ and the US in different groups of animals. Significant differential conditioning was obtained when the onset of the CS+ preceded the onset of the US by 0.5 sec, and marginal conditioning was obtained when the ISI was 1.0 sec. By contrast, no significant conditioning occurred when the CS+ preceded the US by 2, 5, or 10 sec, when the onsets of the stimuli were simultaneous, or when US onset preceded the CS+ by 0.5, 1.0, or 1.5 sec (backward conditioning). We next examined the effect of contingency by giving one group of animals normal differential conditioning, and a second group the same training but with additional USs inserted between the paired trials. Presentation of these additional USs reduced the degree to which the US was contingent on the CS+, but did not change the number of pairings. Animals receiving normal training again showed significant conditioning, whereas animals receiving additional USs showed no conditioning.(ABSTRACT TRUNCATED AT 250 WORDS)

124 citations


Cites background or result from "Probability of shock in the presenc..."

  • ...Furthermore, it often takes more than five trials to establish an effect of contingency in vertebrates (e.g., Rescorla, 1968)....

    [...]

  • ...This procedure decreases the degree to which the US is contingent on the CS, and decreases conditioning (Rescorla, 1968)....

    [...]

  • ...The results of our experiments on the effect of contingency are also qualitatively similar to the results of analogous experiments with rats (Rescorla, 1968)....

    [...]

  • ...For example, many vertebrate behaviors show either a tight interstimulus interval function (e.g., Smith et al., 1969) or a strong effect of contingency (Rescorla, 1968) but not both....

    [...]

References
More filters
Journal ArticleDOI
TL;DR: This "truly random" control procedure leads to a new conception of Pavlovian conditioning postulating that the contingency between CS and US, rather than the pairing of CS andUS, is the important event in conditioning.
Abstract: The traditional control procedures for Pavlovian conditioning are examined and each is found wanting. Some procedures introduce nonassociative factors not present in the experimental procedure while others transform the excitatory, experimental CS-US contingency into an inhibitory contingency. An alternative control procedure is suggested in which there is no contingency whatsoever between CS and US. This \"truly random\" control procedure leads to a new conception of Pavlovian conditioning postulating that the contingency between CS and US, rather than the pairing of CS and US, is the important event in conditioning. The fruitfulness of this new conception of Pavlovian conditioning is illustrated by 2 experimental results.

1,328 citations

Journal ArticleDOI
TL;DR: In this paper, three groups of dogs were trained with different kinds of Pavlovian fear conditioning for three different types of dogs: randomly and independently; for a second group, CSs predicted the occurrence of USs; and for a third group, S predicted the absence of the USs.
Abstract: Three groups of dogs were Sidman avoidance trained They then received different kinds of Pavlovian fear conditioning For one group CSs and USs occurred randomly and independently; for a second group, CSs predicted the occurrence of USs; for a third group, CSs predicted the absence of the USs The CSs were subsequently presented while S performed the avoidance response CSs which had predicted the occurrence or the absence of USs produced, respectively, increases and decreases in avoidance rate For the group with random CSs and USs in conditioning, the CS had no effect upon avoidance

160 citations

Journal ArticleDOI
TL;DR: Rats in an experimental group were given 30 trials of differential CER and then the CS+ and CS− were combined during CER extinction, resulting in less suppression for the experimental group than shown by a control group, interpreted as a demonstration of the active inhibitory properties of CS−.
Abstract: Rats in an experimental group were given 30 trials of differential CER and then the CS+ and CS− were combined during CER extinction. The combination resulted in less suppression for the experimental group than shown by a control group which had a CS+ and a formerly random stimulus combined during extinction. This was interpreted as a demonstration of the active inhibitory properties of CS−.

44 citations


"Probability of shock in the presenc..." refers background in this paper

  • ...Although such an account is plausible for the present data, it fails to explain the active inhibition of fear found by Rescorla and LoLordo (1965), Rescorla (1966), and Hammond (1967)....

    [...]