The Trouble with Tunnel Vision


Police and prosecutors who suffer from tunnel vision are unwitting accomplices in numerous injustices. Tunnel vision is the phenomenon that occurs when police seize on evidence that implicates a person and refuse to consider other evidence that would lead to a different conclusion. It is fed and exacerbated by the cognitive bias of the investigator who looks only for evidence to support the initial conclusion to the exclusion of all other evidence. As noted by journalist Emily Bazelon “It’s a problem that by definition emerges in hindsight. What’s scary is how tenaciously police and prosecutors cling to their initial assumptions-and how much this reflects basic human tendencies.” Numerous hard fought exonerations from around the country have brought the problem to light but little has been done to prevent the injustices from happening. Prosecutors, especially those with crushing caseloads, don’t always take the time to critically examine the materials presented by police investigators seeking arrest warrants. Once the decision is made to go forward on a charge, it is extremely difficult to persuade prosecutors to re-examine the facts and explore alternative hypotheses. (Lest I draw the ire of trial prosecutors who may suggest that I know not of what I speak, please know that I served as the elected prosecutor for 12 years.) What is especially disturbing and always baffling is even when the errors of investigation and tunnel vision are established, prosecutors tenaciously stick to their guns. Innocence Projects throughout the country encounter this every day. One only need study the Garcia case in Illinois or the Morton case in Texas to get an appreciation of how absurd prosecutors can become when the case is irrefutably challenged with evidence that not only undermines the conviction but proves the persons innocence. Law enforcement would do well to enhance critical thinking skills through training which should include cases of tunnel vision that led to a fellow citizen having their freedom taken away by investigator tunnel vision and cognitive bias. Until that happens, we will continue to see these tragic injustices.