What do we think about the person who believes their destiny is ruled by the stars, or is mapped on the lines across their palm, or revealed in the tea leaves at the bottom of a cup? Are they any less delusional than the person who believes God wants them, and only them, to undertake some special task? What are the measurable differences? Could they all be signs of insanity or just some harmless beliefs?
From a psychological perspective a delusion is really a persons' explanation of their experiences. Some of these appear to be quite mild and some quite severe and disabling, which is perhaps why we take notice. Delusions are commonly described as fixed false beliefs. It is also commonly, if wrongly assumed, that only people with schizophrenia experience delusions. In fact delusions are remarkably common and are certainly seen in the population of people who might otherwise be regarded as perfectly normal. So, if delusions are not confined to clinical groups, how are they best explained?
Let's begin by considering both the type and content of delusions. Persecutory delusions are constructed around anxiety and the anticipation of danger. Likewise, grandiose delusions are constructed from feelings of elation, success and achievement. Depressive delusions have their roots in shame, loss and guilt. The underpinning and consistent factor across all these examples is emotion. The intensity of the delusion will correspond with the emotional investment the person has in it.
Now let's consider how a delusion starts. It's not straight forward as beliefs can be constructed in a number of ways. But let's simplify the process by an explanation and an example. The explanation might be due to the way we interpret and label our internal state. In people with delusions there appears to be a mechanisms which incorporates environmental factors as an explanation for internal states. What I mean by this is that people with the most severe or complex delusions tend to draw on a variety of coincidences and socially ambiguous events (e.g. facial expressions) and integrate them into their explanation of the way they feel.
Now an example. A person starts to feel ill after they have eaten in a restaurant. Rather than attributing their feelings of nausea to the meal they have just eaten they begin to ruminate on the facial expression and general demeanor of the waiter who served them, which they regarded as ‘suspicious'. This, they conclude, is evidence of the fact that the waiter has tampered with their food.
The way the person with delusions reasons their way through daily situations is significant. Experimental studies have shown a propensity for people with delusions to jump to conclusions instead of weighing up the information that could prove or disprove their thinking. This, coupled with an inflexibility to change the belief once established, is how the delusion is maintained.
Delusions may be bizarre, as is more commonly the case with schizophrenia or they may be perfectly plausible, as is the case with delusional disorder. The fact that a person has one or more delusions does not, in itself, mean their life should be negatively affected. But common to many people with delusions are social isolation, ruminations, sometimes a physical impairment like deafness, and anxieties about the world in which they live.