Kolbrún Kristinsdóttir

Thesis Title:

The role of extreme overvalued beliefs as a cognitive-affective driver of fixation in lone-actor grievance-fuelled violence.


Extreme overvalued beliefs are a novel concept in clinical and forensic evaluations and describe a non-delusional, emotionally heavy, and ego-syntonic fixation shared with other members of a person’s subculture. The fixation becomes increasingly overbearing, binary, and absolute over time. It is believed to grow rampant within online subcommunities (e.g., Incels) and conspiracy theories (e.g., QAnon) which have driven the will or perceived obligation of individual actors to commit acts of grievance-fuelled violence. Extreme overvalued beliefs often resemble delusions or obsessions in content and behaviour, but distinguishing between them is essential for reliable threat assessment, as the aetiology, cognitive components, and psychopathology can differ significantly.

The current definition of extreme overvalued beliefs in a forensic context also contradicts the definition of overvalued ideas as presented in the DSM-5, where they are described as ideas not shared or accepted by a person’s subculture (p. 826). While the concepts are closely related, the sharing of beliefs is a vital component of overvalued beliefs in threat assessment, which introduces a significant discrepancy and debate regarding a mutually used and agreed-upon understanding in a clinical and forensic context.

To address this limitation, we are conducting a systematic review, a Delphi study, interviews with forensic experts, and a secondary analysis of a European database of terrorist offenders. This is done to further our knowledge and ultimately improve threat assessment protocols and treatment of fixated offenders by understanding the prevalence, aetiology, co-occurring disorders, and psychosocial factors associated with extreme overvalued beliefs and explore how they manifest within different groups/belief systems.


My supervisors are Professor Mark Freestone, Dr Hannah Jones and Dr Alan Underwood.

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