Current cognitive neuropsychology research points toward a two-factor approach to the cause of monothematic delusions.
As an example of one of these first factors, several studies point toward Capgras delusion being the result of a disorder of the affect component of face perception.
[citation needed] An additional second factor—a bias or impairment of the belief formation cognitive process—is likely required to solidify and maintain the delusion.
Additionally, studies[5] have shown that they are more prone to making errors due to matching bias—indicative of a tendency to try and confirm the rule.
These two judgment biases help explain how delusion-prone people could grasp onto extreme delusions and be very resistant to change.