Researchers and mental health professionals use a common definition to describe delusions: a fixed, false belief held despite contradictory evidence (American Psychiatric Association 2013, p. 87). Not only does this definition fail to distinguish delusions from other widespread beliefs, such as religious or ideological beliefs, but it also attempts to simplify delusions to an individual characteristic of irrationality (i.e., the person has failed to distinguish what is true and false; Gold & Hohwy, 2000). This conceptualization of delusions has been criticized, and new theories have emerged that focus on the inherently social nature of acquiring beliefs. This framework might better explain why delusions exist in the general population and identify some ways in which false beliefs can form.
There are many types of delusions, which Gold (2017) clustered into three categories. These categories are not universally accepted (particularly the category of social inferiority), but offer food for thought.
- Persecution – fear of being harmed or controlled by others
- Persecutory delusions: beliefs that an agent or group of agents wants to harm the person
- Delusions of jealousy: beliefs about infidelity
- Delusions of control: beliefs about one’s actions being manipulated by another agent
- Delusions of thought: beliefs that thoughts are being inserted into, or withdrawn from, one’s mind or that one’s thoughts are being read
- Religious delusions – beliefs of being persecuted by supernatural forces
- Grandiosity: being special or particularly capable
- Grandiose delusions: beliefs that one is special or has particular powers
- Referential delusions: beliefs that external events have a special meaning for the person
- Erotomanic delusions: beliefs that someone, usually of high social status, is in love with the person
- Religious delusions: beliefs that one is a religious figure or on a divine mission
- Social inferiority – the opposite of grandiose delusions
- Somatic delusions: anxieties about one’s health or bodily function
- Nihilistic delusions: beliefs concerned with an imminent catastrophe or with nonexistence
Delusions tend to cluster around a surprisingly small subset of social themes about an individual’s position in the social world (Bell et al., 2021). Persecutory delusions are the most endorsed type of delusion (e.g., the government is spying on me and plotting against me; Appelbaum et al., 1999). Researchers have speculated that delusions may represent an extreme end of an adaptive social process shaped by evolution (Bortolotti, 2015). Since humans evolved in complex and dynamic social groups, having specialized social-cognitive abilities, such as being attuned to our social status and danger from others, was beneficial (Gold, 2017).
Delusions are often associated with schizophrenia because they are a core symptom of this mental health disorder; however, delusions are observed across various mental health disorders (Bebbington & Freeman, 2017), neurological disorders, infections, and medications/drugs (Gold, 2017; Manschreck, 1979). Delusions also exist in the general population (Van Os, 2003). For example, an individual with obsessive-compulsive disorder might engage in a repeated action (e.g., sitting in the same seat on a train) because they fear something bad would otherwise happen (e.g., the train would crash). There is no link between the individual’s behavior and the safety of themselves or others, yet they may hold this belief despite contradictory evidence. Does this belief count as a delusion? This example is evidence of a grey area when deciding which beliefs should be considered delusional.
It is estimated that 5-6% of the general population endorse a delusional belief, but this belief may be less distressing or preoccupying than delusions that accompany psychotic disorders (Freeman, 2006). How might these delusional beliefs form? What individuals believe and know is largely based on culture (i.e., knowledge, concepts, rules, and practices transmitted across generations), which operates on both an individual level (e.g., identity or level of adherence to cultural values) and a social level (e.g., families, institutions; Causadias, 2013). Let’s consider a cult that believes their leader has superpowers (e.g., can fly). This belief is passed across generations and maintained in part because of extreme within-group cohesion (i.e., members of the cult tend to only interact with other members in the cult) and lack of contact with out-group members who do not hold these same beliefs (Coates, 2012). If someone outside of the cult challenged a member’s delusion-like belief or they were confronted with contradictory evidence, would the belief dissipate? This example highlights that delusion-like beliefs can be formed through social processes, rather than impairments in rational thinking, and in the absence of mental health disorders (Bell et al., 2021).
What about delusions that no one else holds? Miyazono and Salice (2020) recently put forth an explanation of delusions as a failure of testimony, meaning a failure of social sources of evidence as opposed to a failure of reasoning on part of the individual. This could include a loss of interaction with other people who refute your belief due to being isolated. This explanation fits with research showing that individuals with psychosis (i.e., people experiencing hallucinations and/or delusions) often have fewer interpersonal relationships (Erickson et al., 1989). Additionally, individuals with delusions may discount the testimony/evidence of others, meaning they de-weight the contradictory evidence offered by other people and, thus, do not change their delusional belief (Miyazono & Salice, 2020). This theory explains why delusions are maintained despite contradictory evidence and do not require the individual to be irrational, but rather isolated and untrusting of other people’s contradictory evidence.
Lastly, there does not seem to be a general problem of irrationality among people with delusions, since they hold many other rational beliefs (Gold & Hohwy, 2000; Bell et al., 2021). Schizophrenia is associated with a general cognitive deficit, which has been hypothesized to contribute to delusions, but there is only a weak correlation between poor cognitive performance and the presence of positive symptoms (i.e., hallucinations and delusions; Ventura et al., 2013). Furthermore, cognitive impairment is not sufficient to produce delusions. In the general population, people can have delusional beliefs without any cognitive impairment. Instead, we can think of delusions as ”rational beliefs” given the person’s social circumstances and the evidence available to them.
Determining whether a belief “counts” as a delusion is complicated. It is important for researchers and clinical professionals to consider an individual’s culture before making any conclusions. The formation and maintenance of delusions likely has many causes, but it is clear that beliefs in general are influenced by social processes. Understanding the social processes of belief formation is important, not just for alleviating delusional beliefs, but for understanding and decreasing false, harmful beliefs that members of society hold in general. For example, the false belief that COVID-19 vaccines cause mutations in our DNA recently emerged (Earnshaw et al., 2020). When false beliefs like this spread, they can have negative consequences on human health. An important avenue to target delusions and false beliefs will be through these social processes.
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Edited by Dan Myers and Joe Vuletich