Introduction

Cognitive theories of vulnerability to depression state that cognitive factors are causes in the disorder. This article examines a cognitive theory for depression, namely the dual process model.

A General Dual Process Model

Most dual process models of cognition have three components. First, there is an associative processing component. Associative processing is responsible for fast and effortless information processing. Information previously associated with a particular stimulus becomes active again upon seeing the same stimulus. Past experiences facilitate the processing of current information. Smith and DeCoster (2000) state that associative processing is guided by the correspondence between the current stimulus and information obtained from a previous stimulus. Our impression of a stimulus is a combination of what we see at the moment and what our previous experiences tell us. Associative processing is stable and is being built up slowly. Learning new rules is automatic and does not depend on attention, but it requires many common experiences. This allows it to run faster.

Secondly, there is the reflective processing. Reflective processing is more conscious, but slower than associative processing. It is sequential rather than parallel. It can be influenced by a single experience. Learning new rules depends on attention.

Thirdly, there is the question of when to use associative and when to use reflective processing. Most dual process models agree that associative processing is automatically used. Reflective processing is discussed when expectations are not met. Associative processing is dominant until an unexpected stimulus is discussed, or when associative processing does not lead to the intended outcome. In those cases, they switch to reflective processing. Even when expectations do not come true, there are cases where reflective processing is not possible. Reflective processing takes effort and if cognitive means are limited, reflective processing can be disturbed.

The interaction between associative and reflective processing is important for the regulation of emotions. Forgas (2000) states that associative processing is used to maintain a certain emotional state by bringing in information that is congruent with the current emotion. Reflective processing is used to change emotion by bringing in information that is incongruent with current emotion.

A Dual Process Model for Cognitive Vulnerability to Depression

There is a negative bias with regard to one's self-image during associative processing. This has a cognitive vulnerability to depression. There is a lot of evidence that how a person feels about himself contributes a lot to vulnerability to depression. A self-schema is an organized representation of one's previous experiences. Beck (1979) stated that vulnerability to depression is increased when self-schemas are negative.

When someone has a negative associative processing, reflective processing can still happen to this negative bias. There are at least three cases where associative processing is not corrected. First, when biased associative processing violates expectations, but the cognitive means are not present to switch to reflective processing. In the absence of cognitive burden, people who are vulnerable to depression can use reflective processing to correct their negative associative processing. However, when the cognitive burden is increased through time pressure, a competitive task (such as remembering 6 numbers) or stress, one cannot fall back on reflective processing. The result is that the person's cognitive vulnerability becomes visible.

Secondly, when biased associative processing does not violate anyone's expectations and therefore there is no need for reflective processing. Biased associative processing does not trigger reflective processing in depressed people. Depressed people respond the same to functional and dysfunctional statements, while non-depressed people make more use of reflective processing when expectations are violated.

And third, when biased associative processing violates expectations, but that reflective processing cannot adequately adjust negative bias associative processing. An example is self-reflection. It is often thought that thinking about depression, wondering where the symptoms come from and what the consequences of the symptoms are helps to overcome depression. However, this is not the case. Thinking about depression actually increases depression.

Under each of these circumstances, associative processing is not adequately corrected and therefore a cognitive vulnerability to depression arises. If associative processing remains uncorrected, a negative spiral is created in which the vulnerability to depression becomes worse. The more negative one is in life, the less cognitive means are available to switch to reflective processing. This dual process model emphasizes a negative bias about one's self-image in associative processing and the inability to use reflective processing to correct such biases.

Development of Cognitive Vulnerability

Associative processing is influenced by the rules that have gradually been formed. However, some experiences may have more influence on forming an associative memory network than others. These experiences can be divided into early experiences, affective experiences and cultural biases.

The experiences that someone has early in his / her life have more influence on the formation of an associative memory network than experiences that someone experiences later in life. Depression can develop in people who have experienced experiences early in life that have a negative influence on their self-image.

Affective experiences also have an important role in forming associative processing. Evidence has been found for the hypothesis that associative processing is correlated with parts of the brain that regulate emotional experiences. This suggests that a negative affective experience can have a lot of influence on associative processing.

Finally, cultural beliefs influence the formation of associative processing. Cultural beliefs are often shared by an entire social community. People who belong to a minority group often have the same opinion as the rest of the community. Evidence has been found that African Americans and Whites both have implicit prejudices against African Americans. African-Americans have an associative bias against their own race because they have adopted the negative opinion of society.

Overcoming Cognitive Vulnerability

A dual process model provides some ways in which one can correct for their cognitive vulnerability. Firstly, expectations can be adjusted so that negative bias associative processing gives a trigger to switch to reflective processing. The correct cognitive means must then be present to switch to reflective processing. Another way is to adopt a reflective attitude and realize that the outcome of associative processing is only one perspective and does not necessarily have to be the truth. These strategies only affect the short term. An ideal strategy would be to influence associative processing in such a way that it no longer has a negative outcome. The repeated transition to reflective processing can change associative processing. This process is called consolidation. Consolidation occurs when a person has gained enough experience with a certain association that this new association is integrated into the associative system. However, this process can take weeks to years. This shows that repeated exposure to new associations is needed to consolidate the results from reflective processing to associative processing. A cognitive vulnerability can thus be reduced by repeatedly using reflective processing to correct the bias that results from associative processing.

Conclusion

This article examines a dual process model for the cognitive vulnerability to depression. This model emphasizes the interaction between two models of information processing, namely an associative and a reflective processing model. Associative processing is a fast, automatic form of information processing, while reflective processing is slower and requires more effort. It is assumed that negative associative processing, in particular about self-esteem, increases cognitive vulnerability to depression. However, this bias can be corrected by using reflective processing if the cognitive means allow this. Therefore, a cognitive vulnerability to depression is mainly seen when the cognitive means do not allow this correction.

Uncorrected negative associative processing leads to a depressed mood. As determined by Forgas and Ciarrochi (2002), reflective processing is important for the regulation of depressive moods. If there is no reflection, this depressive mood will only get worse.