Why psychiatrists can’t predict mass murderers
Richard McNally
January 12, 2010
The massacre in Tucson, Ariz., has unleashed a barrage of speculation about the sanity and motives of Jared Loughner, charged with mass murder. Some commentators cite the virulent rhetoric of our polarized political climate as an important cause of the violence, whereas others speculate about the role of mental illness. Driving the debate is the hope that we can identify predictors of mass murder, thereby enabling us to intervene early and prevent similar tragedies in the future.
Shocking, unexpected events motivate a search for explanations that would impose order on an otherwise harrowingly capricious world. The British psychologist Frederic Bartlett noted how people exert an “effort after meaning” to make sense of their experience, and this is especially true for seemingly unpredictable and uncontrollable horrors, which are far more traumatic than ones we can foresee and possibly prevent. The search to make sense of the seemingly senseless is entirely reasonable. Yet several cognitive biases of the human mind make the task of predicting mass violence appear easier than it actually is.
Consider the phenomenon of hindsight bias. As law enforcement investigators uncover more facts about a mass murder, a narrative of how it unfolded emerges. The pieces of the puzzle begin to fall into place, making it easy for us to fall prey to an illusion of inevitability. Once we have a plausible account of what led up to a massacre, it seems obvious that we should have seen it coming. At this point, people begin to ask, “Why didn’t anyone notice that the killer was a walking time bomb, ready to explode?” And if people did notice, why didn’t they do something about it? By making unexpected events seem inevitable in retrospect, hindsight bias can result in finger pointing about who should be held responsible for failing to prevent the catastrophe. Predicting what has already occurred is easy; predicting the future is much tougher.
