Introduction

Current conditioning models are a source of information about learning and performance in various ways. Firstly, it’s now possible to use these models to describe in a reasonably accurate manner the conditions under which associative learning occurs. Secondly, there are important non-associative processes that influence the strength of a conditioned response. Thirdly, the discovery of these non-associative processes has consequences for treatment. There are important procedural and dynamic differences between animal and human conditioning. That’s why it’s important to have a model that, with knowledge about animal conditioning, forms a framework for human conditioning.

Conditioning Processes in Humans

An important development in animal conditioning is that more and more inferential techniques are being used, so that there is now also information about aspects that we can’t see. The two most important developments are the types of associations that are formed during different types of classical conditioning, and the nature of the cognitive representations that influence the conditioned response (CR). Post-conditioning stimulus revaluation is an illustration of this. This procedure consists of three phases:

1. Animals are given pairings of a conditioned stimulus (CS) and unconditioned stimulus (UCS) together until a CR is formed.
2. Then they receive the UCS alone a number of times – revaluation.
3. They receive test presentations from the CS.

The logic behind this is that is that if the CR is mediated by an association between the CS and UCS, then revaluation of the UCS will also affect the CR. In contrast, if the CR is mediated by a reflective association between stimulus and response, then the CR won’t be affected by revaluation, because the UCS has no mediating role. We assume that animals generally learn associations between CS and UCS. This has various implications for our conception of Pavlovian responding. Firstly, it means that the CS activates an internal representation of the UCS and that this representation mediates the CR. Secondly, it means that the strength/nature of the CR depends on how the UCS representation is assessed. Thirdly, the strength of the CR can be modulated by procedures that lead to revaluation of the UCS representation.

It’s been proven in two ways that people also learn the association between CS and UCS. First, research shows that people only show a differential CR if they can verbally represent the contingency between CS and UCS. Secondly, post-conditioning revaluation of the CUS appears to influence the strength of the CR. The revaluation processes can be very important for modulating the strength of the CR in humans. There are a number of ways in which people can achieve revaluation. This can be done through direct experience with the UCS, through socially or verbally transmitting information about the UCS, or through a person’s response/reaction to the CS or UCS. Revaluation can influence the strength of the CR independently of other experiences with the contingency between CS and UCS.

Currently, most animal conditioning models are based on contingency rather than proximity. This means that they emphasize that the proximity between CS and UCS is not sufficient to cause conditioning. More important is the predictive significance of the CS that heralds the UCS. To predict the relationship or covariation between events, situational information and previous expectations about the covariation are needed. The so-called covariation bias can cause a disturbed observation of the covariation. It’s important here that previous experiences can influence the strength and course of conditioning in people.

Latent inhibition – when a CS is repeatedly presented alone before conditioning, it’s more difficult to from an association between the CS and UCS than if the CS is not presented alone. This process can also be shown in people.

Another phenomenon is known as ‘blocking’; if the UCS is predicted by a CS (e.g. A), the combination of the CS (A) and a new component (e.g. B) has little or no effect on B. Blocking is an example of a combination between CS and UCS with no CR. Examples of blocking in people are not always found to be reliable.

Another phenomenon known as sensory preconditioning – if an animal is presented with two neutral stimuli (CS1 and CS2), no behavioural changes occur. However, if the animal then combines the CS2 with a UCS, presentation of the CS1 will also generate the CR associated with the UCS. This phenomenon has also been found in humans. It shows that associative learning can occur without the presents of a differential CR and without an aversive UCS.

Higher-order conditioning means that if the CS has an association with the UCS and can evoke a CR, then the CS can also be used to enhance other possible CS stimuli. Experiments in humans show that the CS2 can be associated with the UCS representation created by CS1, because neither the response to CS1 nor the CS1 itself can make the memory of the aversive UCS disappear.

The foregoing information has made it clear that human conditioning has the most important associative characteristics of animal conditioning. In addition, it’s important to reflect the contingent learning of people in terms of expectations. In other words, people assess the relationship between the CS and the UCS by looking at the relevant information and forming an expectation based on this information. People differ from animals in the sophistication and diversity of information sources. In addition, it’s important to include certain human qualities with regard to nonassociative factors. For example, people can handle problems in a complex way and have different coping styles. In the model illustrated in this article, the ability of the CS to activate a cognitive representation of the UCS depends on the variety of factors that determine what the person expects. The strength of the CR is modulated by processes that influence the assessment of the person. This model differs from traditional conditioning in two ways.

1. The association between CS and UCS is influenced by factors other than the perceived contingency.
2. The strength of the CR is determined by non-associative factors that influence the evaluation of the UCS.

Traditional Criticisms of Conditioning Accounts of Phobia

Now that a model has been established and discussed, it’s possible to review a number of criticisms. First of all, one of the apparent difficulties with a conditioning account of phobias was that it didn’t seem to be able to predict the conditions under which someone would not develop a phobia, since not all individuals experiencing pain or trauma paired with a situation develop a phobia of that situation. The current conditioning theory has various explanations for this: latent inhibition and the dependence on the evaluation of the CUS. Current theory does not expect phobia to arise if the traumatic UCS receives less value immediately after the experience.

Secondly, many anxious people can’t remember trauma. The current model sees the acquisition of an association between CS and UCS and the modulation of a negative UCS as two relatively independent processes.

Third, it was often found that CS presentations only increased anxiety, even though the UCS was not present. this can be explained by the influence of the individual evaluation. Anxious people appear to revive the trauma in their heads and to focus on the traumatic components of an event. This could be sufficient to prevent extinction.

Fourth, there appears to be a disproportionate distribution of fears in the clinical and non-clinical population. Fears are connected with certain situations and events (snakes, spiders) and not with other situations, while other situations (cars, electricity) are often more dangerous. From an evolutionary point of view, an explanation could be that our ancestors have created a predisposition to stimuli that were once a threat. This statement has received much criticism, partly due to the lack of predictive power. A lighter version states that one possesses selective association, meaning that certain incentives are more easily associated with consequences. This so-called ‘willingness’ is not determined evolutionally, but rather by earlier conviction about the relationship between stimuli and outcomes. This can also be found in the current model; the expectation plays a role in this.

The Constituency of Conditioning Models

The purpose of classical conditioning in humans is greater than in animals. We’re not so interested in the factors that determine associative strength, but rather in the understanding of all factors that determine the strength and persistence of a CR. That is why a model is needed that focuses more on the prediction of a performance than on the underlying processes Rachman outlined a ‘three pathways’ model of acquisition:

1. Normal conditioning through direct experience with the trauma
2. Transmission of information
3. Observational learning

There’s evidence that part of the acquisition of phobias goes through the ‘other’ routes, and not through direct experience of a traumatic event. This form of conditioning seems to be more important if there was little prior experience with the stimuli, for example in childhood. Expectations can have two effects. First, they can have an effect on the assessment of covariation and strength of the CR. Secondly, they can develop a differential CR without direct experience with the UCS.

Revaluation can function in a number of ways in fears and phobias. An example is in denial, which appears to have a positive effect in the short term. In addition, many people use a certain way of devaluation as a coping strategy. They make the threat more neutral, use positive comparisons, selectively ignore elements or make the event less important. This coping strategy reduces fear. In addition, different events in a person’s life can influence the evaluation of a trauma. An example of a sudden shift in anxiety is spontaneous remission, in which the symptoms suddenly disappear. This seems to happen more often if there are positive changes in one’s life. The revaluation of trauma is therefore important in the modulation of anxiety. Moreover, it is a determinant of the strength of a CR.

The Scope of Conditioning Models of Phobias

For which fears is such a conditioning model relevant? Not only for simple phobias acquired through conditioning, but also for phobias that arise from, for example, observation. The relevance of the model for mild non-clinical fears is not entirely clear. A major obstacle is the lack of empirical evidence. It must be established to what extent associative phenomena and the effects of revaluations are identified in terms of ontogeny, remission, and maintenance. Moreover, it’s suggested that conditioning is involved in panic attacks. The ‘catastrophic interpretation’ of feelings is an important part of this. The model also suggests a combination of associative and cognitive factors.

Implications for Treatment

The most important aspects of the current conditioning approach to anxiety are the consequences for therapy:

• With latent inhibition and blocking in mind, regular nontraumatic exposure to situations as early as possible seems very useful. This is a preventative method that is already widely used (e.g. in dentistry).
• Acquiring fears and phobias is influenced by individual coping strategies, which can be influenced by coping skills and positive thinking.
• The revaluation of stimuli is important, for example by convincing the patient that the stimulus is no longer a threat. Evaluation and expectation don’t’ seem to depend solely on verbal information, making therapy more difficult.
• Selfobservation of a person’s response to a feared stimulus can be a cause for changing the evaluation of the UCS, exposure can help with this.