Probability of shock in the presence and absence of CS in fear conditioning.
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148 citations
Cites background from "Probability of shock in the presenc..."
...Since Rescorla (1968) showed that, for classical conditioning, if one removed the contingency between the conditioned stimulus (CS) and the unconditioned (US), preserving the temporal pairing between CS and US but adding additional trials where the US appeared on its own, animals consequently did…...
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147 citations
Cites background from "Probability of shock in the presenc..."
...Fear conditioning experiments form the cornerstones of contemporary theories of learning (e.g., Rescorla, 1968), and contextual learning has also been theoretically explored (Nadel and Willner, 1980)....
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146 citations
Cites background from "Probability of shock in the presenc..."
...Classical conditioning has been demonstrated in animal experiments even when only one in ten CSs is followed by a US (e.g., Rescorla 1968)....
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144 citations
Cites background or result from "Probability of shock in the presenc..."
...In fact Rescorla and Wagner (1972) discuss an initial learning effect according to which low levels of associative strength can be expected to accrue briefly to the background stimuli at all P(US/CS) levels during the first few learning trials. The apparent conflict between the data and the theory is therefore capable of resolution without going outside the theory provided it is assumed that in both experiments it was initial learning rather than asymptotic learning that was monitored. The assumption is rendered plausible by two features common to both experiments. First only a small number of training trials were given to subjects. Second the experimental situation employed was one likely to have been sensitive to low levels of fear. In conclusion it seems that the results of both of the present experiments can be explained by Rescorla and Wagner’s (1972) theory of Pavlovian conditioning....
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...Generally therefore, the results of Experiment I appeared to support Rescorla and Wagner's theory. The experiment demonstrated that background stimuli can act as potent variables in a Pavlovian conditioning situation. Moreover the results were consistent with the view that background stimuli act with the manipulated CS as elements within a complex compound stimulus. As predicted, the associative strength of the background stimuli, derived in this case from the black compartment of the apparatus, was found to depend upon the reinforcement history of the CS. As P(US/CS) increased, and hence as P(US/NoCS) decreased, the associative strength of these stimuli apparently diminished so that subjects became increasingly ready to re-enter and remain in the environment in which they had just received 10 shocks. With respect to the other variable tested, namely US intensity, the finding that the post-training reactions of subjects to the background stimuli were a function of US intensity could similarly be reconciled with the theory, although perhaps less readily. According to Rescorla and Wagner (1972) increasing US intensity should have two different effects....
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...In fact Rescorla and Wagner (1972) discuss an initial learning effect according to which low levels of associative strength can be expected to accrue briefly to the background stimuli at all P(US/CS) levels during the first few learning trials....
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...At present Rescorla and Wagner's theory does not provide rules for the detailed mapping of different values of associative strength on to behaviour (Rescorla and Wagner, 1972). It therefore predicts no more than the ordering of results. Nevertheless this particular result was unexpected partly because it was in conflict with data previously reported by Rescorla (1968). Using rat subjects in a Conditioned Emotional Response (CER) experiment, which involved the monitoring of subjects' post-training reactions to the manipulated CS rather than to background stimuli, Rescorla obtained a regular family of curves relative to manipulations of the P(US/CS) variable. On the other hand Willis (1969) also using rat subjects in a CER experiment, reported a marked discontinuity in the data relative to the P(US/CS) variable in the region of 0....
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...At present Rescorla and Wagner's theory does not provide rules for the detailed mapping of different values of associative strength on to behaviour (Rescorla and Wagner, 1972). It therefore predicts no more than the ordering of results. Nevertheless this particular result was unexpected partly because it was in conflict with data previously reported by Rescorla (1968). Using rat subjects in a Conditioned Emotional Response (CER) experiment, which involved the monitoring of subjects' post-training reactions to the manipulated CS rather than to background stimuli, Rescorla obtained a regular family of curves relative to manipulations of the P(US/CS) variable....
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144 citations
References
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"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)....
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