What delusions can tell us about the cognitive nature of belief

Natalie also recalled other beliefs, including that she was dead (known as Cotard delusion), which she did not share with clinicians at the time. She noted that she entertained this idea due to the failure of other explanations to account for her strange experiences and an idea from a television show.

Natalie said she eventually dismissed this idea as implausible while still holding other delusional ideas. This suggests that belief evaluation may involve different thresholds for different delusions. It also highlights the private nature of some delusions.

Across all of her delusions, Natalie described her active involvement in trying to explain and manage her experiences. She reported considering different explanations and testing these by seeking further information. For example, she asked questions of the people she thought were her in-laws. This suggests a surprisingly similar approach to how we typically form beliefs.

Natalie recalled the influence of television and movies on her ideas. She also recalled how she elaborated on her delusions, once formed, based on information in her surroundings.

These features challenge theories that delusions simply arise from anomalous sensory data. They instead highlight the role of the individual’s search for meaning and social context, as well as the subsequent impact of delusions on perception and thinking.

Implications

As a case study, Natalie’s experiences are not necessarily representative of all people who experience delusions or postpartum psychosis. However, Natalie’s case presents informative features that theories of delusions need to account for.

In particular, Natalie’s personalized insights highlight the critical role of the individual in actively trying to understand their experiences and bestow meaning. This is opposed to just passively accepting beliefs in response to anomalous sensory data or neuropsychological deficits. This suggests psychological therapies may be useful in treating psychosis, in combination with other treatments, in some cases.

More generally, Natalie’s account reveals commonalities between delusions and ordinary beliefs and supports the view that delusions can be understood in terms of cognitive processes across the stages of normal belief formation that we identified.

While there remain challenges in investigating delusions, further study may offer insights into the underpinnings of everyday belief and, in turn, of ourselves.

Michael Connors, Conjoint Senior Lecturer in Psychiatry, UNSW Sydney, and Peter W Halligan, Hon Professor of Neuropsychology, Cardiff University. This article is republished from The Conversation under a Creative Commons license. Read the original article.