A concerning shift can occur in the human mind after spending significant time in the sewers of the internet. Beliefs that start from a grievance can head down a dangerous path to become “extreme overvalued beliefs”—firmly held convictions that are shared and amplified within online communities and can have devastating consequences. This is also known as a contagion effect or "copycat" phenomenon. (As I will explain, threat assessment professionals utilize behavioral patterns to thwart attacks.) At the heart of these observed patterns are pathological fixations that are shaped through interactions with others.

Overvalued ideas, first described by neuroscientist Carl Wernicke, have been part of psychiatric scholarship for over 125 years. They are seen in eating disorders, body dysmorphic disorders, hoarding, and in querulant litigants. An extreme overvalued belief is shared by others in a person's cultural, religious, or subcultural group (including online) and should be differentiated from a delusion or obsession. The belief is often relished, amplified, and defended by the possessor. Over time, the belief grows more dominant, more refined, and more resistant to challenge. The individual has an intense emotional commitment to the belief and may carry out violent behavior in its service. Over time, these beliefs become increasingly binary, simplistic, and absolute. Data sets from studies utilizing proximal warning behaviors and distal characteristics of the Terrorist Radicalization Assessment Protocol (TRAP-18), developed by Dr. Reid Meloy, show that pathological fixations are present in 81% of cases. This protocol has been applied to a variety of targeted violence studies, including school shooters.

Let's consider the 2018 shooting at Marjory Stoneman Douglas High School, where 17 students and........

© Psychology Today