Conditioning circuits

A circuit of mutually exciting neurones capable of approaching and maintaining a state of permanent excitation has been described by Rashevsky as a possible mechanism for the production of conditioned reflexes. The mode of approach of such a circuit to the steady state is examined in some detail under slightly more general assumptions, and an estimate is made of the order of magnitude of the time required to reach this state.     

Conditioning in human opiate addicts

Eight volunteers maintained on daily methadone participated in a classical conditioning procedure to determine which if any of the elements of narcotic withdrawal could be conditioned. The unconditioned stimulus was the injection of a small dose of naloxone. The unconditioned response was a brief precipitated withdrawal syndrome. The conditioning stimulus was a tone, odor, and injection of saline. Conditioning was successful in the pilot study in 5 of 8 subjects. The conditioned response consisted of tearing, yawning, lacrimation, systolic blood pressure increase, respiratory irregularities and subjective feelings of narcotic withdrawal sickness (nausea, muscle aches, chills). A second group of 8 subjects showed, in addition to the above, evidence of conditioning of heart rate, respiratory rate and skin temperature decrease. These laboratory findings support the clinical reports of a conditioned withdrawal syndrome and suggest ways to improve treatment results by detecting and extinguishing or modifying conditioned responses.     

Control over sensory change versus sensory state preference in sensory contingent bar pressing

Sixteen rats selected as high responders in a sensory contingent bar pressing situation, were studied when they had free access to four different sensory states. The experimental procedure allowed choices (entries into states) and preferences (as reflected by time spent in states) to be measured simultaneously. Although clear and consistent preferences were observed, they proved to be a relatively weak predictor of choice behaviour. Implications for theories of choice were discussed and the results were interpreted in accordance with the hypothesis that control over the environment has motivational and reinforcing properties.     

Blocking in Human Electrodermal Conditioning

Associative blocking in human conditioning was investigated using electrodermal and self-reported US expectancy measures. Previous null results using a design reported by Lovibond, Siddle, and Bond (1988) suggested that a clearly demarcated phase structure and visual cues with semantic content may have distracted attention from the experimental contingencies. Therefore the current experiment intermixed pre-training and compound training trials and masked the transition to the test phase to remove or reduce phase boundaries. Simple coloured squares were used as CSs to reduce semantic content. A significant blocking effect was observed on both the expectancy measure and on the electrodermal measure. Both results were due to improved transfer of conditioning to the target CS in the overshadowing control group in comparison to previous experiments. The results were interpreted as providing evidence that previous null results were due to failure of transfer of learning across clearly distinct phases. There was no evidence of a dissociation between the electrodermal and self-report measures. Theoretical and procedural implications for human Pavlovian conditioning are discussed.     

Bidirectional Instrumental Conditioning

Three experiments examined bidirectional instrumental conditioning by training hungry rats to push a pole in one direction for food pellets and in the other for either a sugar or a starch solution. In the first study we examined whether the animals learned about the actionreinforcer relations using a specific satiety procedure. Prefeeding one type of reinforcer before an extinction test selectively depressed the performance of the action that had been paired with this reinforcer during training. The second experiment investigated the sensitivity of the bidirectional actions to variations in the action-reinforcer contingencies. When the instrumental contingency was degraded by presenting unpaired reinforcers, the animals pushed less in the direction that was paired with the reinforcer type that was the same as the non-contiguous one. A third study revealed that increasing the rate of reinforcement for one action enhanced its rate of performance without significantly affecting the performance of the other action. We conclude that the effects of reinforcer devaluation, the action-outcome contingency, and the rate of reinforcement are not mediated by Pavlovian associations between the manipulandum and the reinforcer.     

Conditioning as sensitization

The concept of sensitization has a long history in psychology, and on both empirical and logical grounds it has been argued that sensitization and conditioning denote different neurophysiological processes. Investigators have devised elaborate control procedures that purport to differentiate sensitized and conditioned responses. But, mainly on logical grounds, it is argued that there is no valid basis for considering sensitization and conditioning as separate processes. A theory of learning is proposed in which sensitization is the basic construct.     

Word Diagrams in Teaching Classical Conditioning

The Psychological Record - The present experiment examined the value of word diagrams on the concept learning of university students. All students learned the concept of classical conditioning by...     

Conditioning experiences in spider phobics.

Using the Phobic Origin Questionnaire (Ost, L. G. & Hugdahl, K. Behaviour Research and Therapy, 19, 439-477, 1981), the present study examined the extent to which severe spider phobics (N = 42) attributed their phobia to conditioning experiences, modeling experiences and/or informational learning experiences. Modeling was most often reported (71%), followed by conditioning (57%), and informational learning experiences (45%). It was also found that patients with a conditioning background reported less extreme cognitive symptoms when confronted with the phobic stimulus than patients with an indirect mode of acquisition (modeling and/or informational learning).     

Speech abnormalities in seizures: a comparison of absence and partial complex seizures

In order to determine whether speech changes are useful in differentiating seizure types, a study was done in which speech abnormalities during two distinct seizure types, partial complex and absence seizures, were compared. Speech changes noted during prolonged electroencephalographic and video monitoring were compared in 16 patients with 47 partial complex seizures and 19 patients with 95 absence seizures. Speech changes were common during both seizure types. Although some significant differences in speech patterns were noted in the two seizure types, the degree of overlap was such to preclude using speech changes alone as the sole clinical criteria in differentiating the seizures.     

Epileptic seizures in multiple sclerosis

Starting from informations in the literature, the authors deals with eight own cases, suffering from clinically certain multiple sclerosis and showing, as a further sign, epileptic seizures. Compared to the total of patients, these eight cases represent 1.78 p.c. of all patients treated for multiple sclerosis in this clinic. The features of seizures, frequency and dynamics of occurrence are referred to. The authors point out that it is necessary to differential between epileptic seizures and non-epileptic attacks, and they draw attention to the fact that here are difficulties with regard to differential diagnosis if epileptic seizure appears as a initial symptom of multiple sclerosis.     

Conditioning and Interpretation Shifts

This paper develops a probabilistic model of belief change under interpretation shifts, in the context of a problem case from dynamic epistemic logic. Van Benthem [4] has shown that a particular kind of belief change, typical for dynamic epistemic logic, cannot be modelled by standard Bayesian conditioning. I argue that the problems described by van Benthem come about because the belief change alters the semantics in which the change is supposed to be modelled: the new information induces a shift in the interpretation of the sentences. In this paper I show that interpretation shifts can be modeled in terms of updating by conditioning. The model derives from the knowledge structures developed by Fagin et?al [8], and hinges on a distinction between the propositional and informational content of sentences. Finally, I show that Dempster-Shafer theory provides the appropriate probability kinematics for the model.