Kolbrun KristinsdottirEmail: k.h.kristinsdottir@qmul.ac.ukProfileTeachingProfilePhD title: The role of Extreme Overvalued beliefs in lone actor violence I started my PhD at the Unit for Psychological Medicine, Centre for Psychiatry and Mental Health, in 2022. I hold a BSc in psychology from Reykjavik University and an MSc from the London School of Economics and Political Science. My PhD explores fixation driven by extreme overvalued beliefs as a risk factor for lone-actor grievance-fuelled violence. Extreme overvalued belief is a novel concept in clinical and forensic evaluations and refers to a cognitive-affective driver of fixation. The content and intensity of the belief can often resemble a delusion or obsession. Still, extreme overvalued beliefs are theorised to have a distinct aetiology and development as they are shared, ego-syntonic, and grow increasingly dominant, overbearing and resistant to change over time. Extreme overvalued beliefs seem to grow rampant within violent subcommunities that develop through social media, such as for the Involuntary Celibates (Incels), and in relation to conspiracy theories, like Qanon. In the past, these ideologies have driven the will, need or perceived obligation of individual actors to commit acts of lone-actor grievance-fuelled violence. However, the risk stemming from extreme overvalued beliefs is only theorised as no reliable forensic and clinical tools have been developed, partly due to a lack of consistency in conceptualisation and terminology. Therefore, to address this limitation, the purpose of my PhD project is to reach a consensus among forensic experts by first conducting a systematic scoping review followed by a Delphi study and semi-structured interviews. My PhD is funded by the London Interdisciplinary Social Science Doctoral Training Partnership (LISS DTP) from the Economic and Social Research Council (ESRC). Supervisors: Prof Mark Freestone, Dr Hannah Jones and Dr Alan Underwood. TeachingI am currently a teaching associate on the MSc programme in Forensic Mental Health: Research and Practice, and the BPS-accredited MSc in Forensic Psychology and Mental Health.Research