(Mal)adaptive Mentalising in the Cognitive Hierarchy, and its link to paranoia

Humans need to be on their toes when interacting with competitive others to avoid being duped. Too much caution out of context can, however, be detrimental and produce false beliefs of intended harm. Here, we offer a formal account of this phenomenon through the lens of Theory of Mind. We simulate agents of different depths of mentalization within a simple game theoretic paradigm and show how, if aligned well, deep recursive mentalization gives rise to both successful deception as well as reasonable skepticism. However, we also show that if a self is mentalising too deeply -hyper-mentalising - false beliefs arise that a partner is trying to trick them maliciously, resulting ina material loss to the self. This theory offers a potential cognitive mechanism for suspiciousness, paranoia, and conspiratorial ideation. Rather than a deficit in Theory of Mind, paranoia may arise from the application of overly strategic thinking to ingenuous behaviour.