Model Of Classical Conditioning Research Articles

A bottom up approach towards the acquisition and expression of sequential representations applied to a behaving real-world device: Distributed Adaptive Control III

Biological systems display a high degree of flexibility in problem solving. In this paper a model is presented, Distributed Adaptive Control III (DACIII), which is aimed at understanding these forms of behavior. DACIII is part of a larger modeling series directed at understanding how biological systems acquire, retain, and express knowledge of the world. This modeling series has its roots, on one hand, in the methodological consideration that brain and behavior need to be modeled from a multi-level perspective. On the other, the importance of the acquisition of representations of events in the world, as opposed to an a priori specification, is emphasized. DACIII is presented against the background of the paradigms of classical and operant conditioning. On the basis of an analysis of these experimental approaches towards the study of animal behavior a theoretical framework is defined aimed at identifying the minimal requirements of a control structure which could display these behaviors. The proposed model is evaluated in different configurations using both simulated and real robots. It is demonstrated that DACIII is able to fully bootstrap itself from a mode of control which solely relies on proximal sensors and predefined reflexes, to a level of control which is dominated by acquired representations of events transduced by distal sensors. This transition is reflected in the performance of the behaving device, from strongly variable trajectories to highly structured behavioral sequences. The results are compared with alternative models of classical and operant conditioning and models which attempt to capture the properties of its underlying neural substrate.

Effect of stage of change on cue reactivity in continuing smokers.

Three classical conditioning models (the conditioned compensatory response, conditioned withdrawal, and conditioned appetitive motivational models) postulate that drug cues evoke physiological and emotional responses associated with motivational states that prompt drug use. There is accumulating evidence to suggest that factors other than classical conditioning can influence emotional and physiological reactivity to drug stimuli. This study tested whether stage of change affects the nature of reactivity to smoking cues among continuing smokers. Precontemplators (smokers not considering quitting) and contemplators (smokers considering quitting in the near future) watched videotapes containing smoking cues. Emotional and physiological responses to the smoking video were contrasted with responses to a neutral videotape. Precontemplators had lower heart rates than did contemplators in response to the smoking videotape. Both contemplators and precontemplators evinced increased positive affect in response to the smoking cue. A comparison sample of nonsmokers did not show any reactivity to the smoking cue. Implications of these findings for conditioning theories of smoking are discussed.

Effects of US-Alone Presentations on Human Evaluative Conditioning

In the context of evaluative conditioning, the effects of additional presentations of the unconditioned stimulus (US) prior to conditioning (US preexposure) or after conditioning (US postexposure) were examined using between- and within-subjects control conditions. Two experiments that differed with respect to the nationality of the subjects were conducted. In both experiments, US-alone presentations reduced the magnitude of the evaluative response. The US pre- and postexposure effects were observed in subjects classified as aware as well as in subjects classified as unaware of the experimental contingencies. Another finding is that the evaluative conditioning procedure described by Martin and Levey (1978; Levey & Martin, 1975) resulted in reliable conditioning effects also in an American sample, thus extending the scope of that special evaluative conditioning paradigm. The findings are discussed in the context of recent models of classical and evaluative conditioning. Especially, the unexpected US postexposure effect gives rise to speculations concerning the learning process underlying evaluative conditioning.

The Transition from Automatic to Controlled Processing

The transition from automatic (unconscious) to controlled (conscious) processing is described in terms of a neural network model of classical conditioning ( Schmajuk et al., 1996). In the framework of the network, an environmental stimulus is processed in controlled or conscious mode when Novelty and attention to the stimulus are large, and in automatic or unconscious mode otherwise. In the model, indirect dopamine (DA) agonists, such as amphetamine or nicotine, enhance the DA representation of Novelty, thereby increasing attention and engaging conscious processing of environmental stimuli. By contrast, DA receptor antagonists, such as haloperidol, reduce the DA representation of Novelty, thereby decreasing attention, and engaging unconscious processing of the stimuli.

A Real-Time Neuronal Model of Classical Conditioning

A new neuronal model of classical conditioning is proposed. The model, called the delay-producing connections (or DPC) model, is an extension of Klopf's (1988) drive-reinforcement model and Sutton and Barto's (1981) model. The DPC model makes two contributions: lt represents the trace of each conditioned stimulus (CS) by a differential equation; and it replaces each CS in the activation rule by its CS trace, which is assumed to be equal to the CS eligibility. The DPC model reproduces the usual shape of a conditioned response, the curve of efficacy of conditioning as a function of the interstimulus interval (ISI), the dependence of the optimal ISI on CS duration, the extinction of a conditioned response [even for long-lasting CSs as opposed to Klopf's (1988) model], and several other properties of classical conditioning.

Expectancy and conditioning in placebo analgesia: Related or independent mechanisms?

T he role of cognition in conditioning has been one of the central disputes in the history of experimental psychology. Strict behaviorists view conditioning as mechanistic process in which consciousness is irrelevant [4,12,18]. In contrast, cognitive theorists argue that conditioning effects are mediated by expectancy [13]. Although mechanistic theories held sway during most of the twentieth century, the tide seems to have shifted, and cognitive interpretations of classical and operant conditioning now predominate [10,11]. In their Focus article, Price and Fields propose that classical conditioning affects placebo analgesia in two ways. First, there is a classical conditioning effectthar occurs without the subject's conscious awareness of the conditioned stimuli-unconditioned stimuli (CS-US) association, and second, classical conditioning may alter expectancies, as proposed by Reiss [9] for conditioned anxiety and Kirsch [5-7] for conditioned placebo effects. The first of these views is consistent with stimulus-substitution models of classical conditioning, which have formed the basis of most conditioning accounts of placebo effects [19], but are widely regarded as outmoded [10]. In this Commentary, I argue that the data support the mediational but not the mechanistic interpretation of conditioning effects. Elsewhere, I have summarized much of the data supporting mediational interpretation of conditioned placebo effects [6,7]. As Price and Fields note, many of these data are derived from placebo effects on responses other than pain. It is possible that the mechanisms of placebo analgesia differ from those of placebo-

Stimulus contingencies that permit classical conditioning of opioid activity in the rat fetus.

In a prenatal model of classical conditioning, rat fetuses received presentations of an artificial nipple (conditioned stimulus; CS) paired with milk (unconditioned stimulus). Infusion of milk promotes activity in the kappa opioid system of the fetus, but after 2, 3, or 6 pairings with the artificial nipple, milk evoked both kappa and mu opioid activity. The nipple CS has no effect on opioid activity, but after pairing with milk evoked a mu opioid response. Conditioned mu opioid activity was evident in 60% of subjects tested after 1 paired conditioning trial. Significantly more fetal subjects (90%) exhibited conditioned opioid activity if preexposed to the nipple twice before conditioning. CS preexposure altered behavior during the conditioning trial, with preexposed fetuses showing more pronounced responses to milk infusion. Exposure to familiar stimuli facilitates classical conditioning of physiological responses, including opioid activity, during the first suckling episode.

Variables associated with anticipatory nausea and vomiting in pediatric cancer patients receiving ondansetron antiemetic therapy.

Investigated the prevalence of anticipatory nausea and vomiting (ANV) among 59 pediatric cancer patients who had routinely received ondansetron (Zofran) antiemetic therapy and determined patient- and treatment-related factors associated with ANV. Of the sample, 59% indicated at least mild ANV symptoms, suggesting that a significant number of patients report ANV and are bothered by it, despite the use of Zofran. These children were compared to those reporting no ANV symptoms. Most ANV symptomatology was consistent with a traditional classical conditioning model although cognitive processes may also play a role. Children with greater expectations of severe postchemotherapy vomiting and those who were more distressed by nausea and vomiting were more likely to experience ANV symptoms. Implications for psychological and pharmacological treatments of ANV are discussed.

Heyman's steady-state theory of addiction

AbstractHeyman's target article contributes to our understanding of addictions by offering solutions to several paradoxes and by recognizing the stable nature of addictive behavior. Previous classical and operant conditioning models have emphasized molecular processes, such as acquisition and extinction, and have failed to address the aggregate effects of long-term exposure to the contingencies of drug and alcohol use.

Human Evaluative Conditioning without Experiencing a Valued Event

Two experiments were conducted to examine whether sensory preconditioning is demonstrable in the evaluative conditioning paradigm. Both experiments included between- and within-subjects control conditions. In Experiment 1, forward pairings of the preexposed stimuli were used, whereas in Experiment 2, forward and backward pairings were employed. The results show that affective–evaluative learning is sensitive to a sensory preconditioning procedure, thus demonstrating that evaluative conditioning does not require the direct experience of a valued event. The subjects did not show any signs of verbal knowledge of the stimulus arrangements. The results are discussed in the context of recent models of classical and evaluative conditioning.

An attractor neural network model of classical conditioning.

Living beings learn to associate known stimuli that exhibit specific temporal correlations. This kind of learning is called associative learning, and the process by which animals change their responses according to the schedule of arriving stimuli is called "classical conditioning". In this paper, a conditionable neural network which exhibits features like forward conditioning, dependency on the interstimulus interval, and absence of backward and reverse conditioning is presented. An asymmetric neural network was used and its ability to retrieve a sequence of embedded patterns using a single recalling input was exploited. The main assumption was that synapses that respond with different time constants coexist in the system. These synapses induce transitions between different embedded patterns. The appearance of a correct transition when only the first stimulus is applied, is interpreted as a realization of the conditioning process. The model also allows the analytical description of the conditioning process in terms of internal and external or researcher-controlled variables.

Multiple Chemical Sensitivities–Syndrome and Solution

After describing two patients seen by the author, we define multiple chemical sensitivities and discuss the scope of the problem and the epidemiology. Although the incidence of multiple chemical sensitivities is not known, the demographics are similar to that of agoraphobia. The classical conditioning model is proposed as a useful description of multiple chemical sensitivities. The desensitization approach to the diagnosis and treatment is proposed. Results with three patients were encouraging and the approach seems worthy of further evaluation and refinement.

A conditioning reinterpretation of cognitive events in alcohol and drug cue exposure

Cue exposure treatments of alcohol and substance abuse disorders are based on a classical conditioning model of drug use and relapse. Recently, social learning theory has been utilized to explain the relationship of cognitive constructs (i.e., self-efficacy, outcome expectations) to measures of cue reactivity. However, social learning theory has not provided clear and testable mechanisms by which cognitions influence behavior. This paper proposes a mechanism, based on principles of classical conditioning, whereby cognitions may influence reactivity to alcohol and drug cues. This view of cognitions within a conditioning framework has several important implications for cue exposure research and treatment.

Brief Treatment of Children's Dental Pain and Anxiety

Pain interferes with children's dental care, but anxiety and pain are often confounded. We tested a classical-conditioning model of dental pain with 45 8- to 11-yr.-old children but found little support for it. Instead, different treatments for pain were effective in reducing the children's expectations of discomfort. Expected discomfort may be the most important part of dental pain, so expectations might well be the focus of such treatments.

Classical conditioning and cognitive determinants of subjective craving for opiates: an investigation of their relative contributions.

Subjective craving for drugs is frequently reported by detoxified addicts. Explanatory models emphasizing classical conditioning (CC) and cognitive mechanisms have been proposed, and the mechanisms postulated by the two approaches are discussed here. There are three major variants of the CC model, arguing that craving is associated with conditioned changes which are respectively drug-agonistic, opponent-process, or withdrawal reactions. The cognitive model highlights the role of 'outcome expectancies' as determinants of both appetitive and avoidant motivations. The present investigation has identified correlates of craving predicted by the above models, and tested them empirically. Detoxified opiate addicts participated in in a Craving Test requiring them to rate their craving, physical state, and emotions during exposures to both neutral and drug-related material. Other measures, including personality and outcome expectancies for drug use, were also taken, and interrelationships among the variables were explored statistically. Whilst some of the predictions of the CC formulations were borne out, the cognitive model received more consistent support. The theoretical and treatment implications of these data are considered.

Classical conditioning as a nonstationary, multivariate time series analysis: A spreadsheet model

The implementation of the Gallistel (1990) model of classical conditioning on a spreadsheet with matrix operations is described. The model estimates the Poisson rate of unconditioned stimulus (US) occurrence in the presence of each conditioned stimulus (CS). The computations embody three implicit principles:additivity (of the rates predicted by each CS),provisional stationarity (the rate predicted by a given CS has been constant over all the intervals when that CS was present), andpredictor minimization (when more than one solution is possible, the model minimizes the number of CSs with a nonzero effect on US rate). The Kolmogorov-Smirnov statistic is used to test for non-stationarity. There are no free parameters in the learning model itself and only two parameters in the formally specified decision process, which translates what has been leamed into conditioned responding. The model predicts a wide range of conditioning phenomena, notably: blocking, overshadowing, overprediction, predictive sufficiency, inhibitory conditioning, latent inhibition, the invariance in the rate of conditioning under scalar transformation of CS-US and US-US intervals, and the effects of partial reinforcement on acquisition and extinction.

An auditory conditioned stimulus modulates unconditioned stimulus-elicited neuronal activity in the cerebellar anterior interpositus and dentate nuclei during nictitating membrane response conditioning in rabbits.

The effects of the presentation of an auditory conditioned stimulus (CS) on unconditioned stimulus (US)-elicited neuronal activity in the anterior interpositus (AIPN) and dentate (DN) nuclei of the cerebellum were investigated during the initial stages of classical conditioning of the nictitating membrane (NM) response in rabbits. In Experiment 1, a 500-ms CS (but not a 30-ms CS) facilitated US-elicited single-unit activity in the AIPN and depressed US-elicited activity in the DN during training. In Experiment 2, lesions of the AIPN but not of the DN prevented acquisition of conditioned NM responses. The results are interpreted within the framework of a model of classical conditioning that proposes that conditioned neuronal activity that underlies behavioral plasticity develops from the modulation of US-elicited neuronal activity by the CS.

Distributed adaptive control: The self-organization of structured behavior

Starting with a neural model for classical conditioning we have developed a system for robot control that is completely self-organizing. Instead of relying on predefined control rules the system will develop adapted control by interacting with its environment. We have tested this model in navigation tasks. Our results demonstrate that the level at which control models are normally defined seems to emerge out of the neural level which implements our control architecture.

Classical conditioning and the acquisition of human fears and phobias: A review and synthesis of the literature

This paper is an attempt to consider classical conditioning models of human fears and phobias in a contemporary context, and to consider how conditioning models might be of some theoretical help in this area. The paper covers (i) a contemporary review of the basic phenomena of human conditioning, (ii) a comparison of conditioning processes in humans and animals, (iii) a description of a contemporary model of human conditioning designed to accommodate recent research findings, (iv) a re-examination of the traditional criticisms of conditioning accounts of phobias in the light of this contemporary model, (v) a discussion of some of the features of fears and phobias that this model can address, and (vi) a brief discussion of the scope of this model and some implications for the treatment of clinical fears and phobias.

Characterization of a psychophysiological model of classical fear conditioning in healthy volunteers: influence of gender, instruction, personality and placebo

Two experiments are described which evaluate the role of associative mechanisms and placebo effects on aversively conditioned skin conductance responses in groups of healthy volunteers. In both experiments, skin conductance level (SCL), variability (spontaneous fluctuations, SF) and amplitude (SCR) were recorded during a sequence of tone stimuli (80 dB, 1 s, 360 Hz). All the variables habituated during the first ten presentations of the tones. Tone 11 was immediately followed by a loud (100 dB) aversive brief (1 s) white noise UCS. The conditioning trial significantly enhanced SCRs to a further ten presentations of the tones and increased SCL and variability (SF). No enhancement of SCRs occurred when tone 11 was omitted and the UCS occurred in temporal isolation (experiment 1). Thus enhanced SCRs to tones following paired tone-noise presentation involves an associative mechanism. Increased "spontaneous" variability was shown to involve both conditioning and sensitization following the UCS. In both experiments females showed greater conditioned SCRs than males. In experiment 2 no effect of "anxiolytic" placebo could be discerned and there were no general relationships between questionnaires scores of extraversion or neuroticism with skin conductance measures in a group of 40 volunteers. The results question the role of conditionability and autonomic lability as major determinants of extraversion and neuroticism. These studies validate the use of the psychophysiological model of aversive conditioning in pharmacological studies of the mechanisms of habituation, conditioning and sensitization.