Hindsight Bias in Legal Decision Making

Hindsight Bias in Legal Decision Making^[a]

Breyanna Jones

Georgia State University

150 million people watched one of the most viewed trials in television history on October 3, 1995. An unprecedented number of activities were put on hold while America anxiously awaited the verdict of the O.J. Simpson trial. Simpson, a highly famous football player, accused of murdering his ex-wife and her friend, was acquitted of the killings two decades ago. The world was shocked when the non-guilty verdict was announced;, however, many of us “knew it all along.” In fact, McGlynn (2000) conducted a study to demonstrate just how likely the hindsight bias was amongst undergraduate students’ predictions about the O.J. Simpson verdict. McGlynn’s results found an increase in the enormity of the hindsight bias over time. Before the verdict, 48% of the participants predicted an acquittal. A week after revealing the decision, the participants were asked about their predictions as if they were unaware of the actual outcome, in which the percentage rose to 58%. A year later, the experimenter asked the participants about the trial and their predictions of acquittal expanded to 68%. The failure and systematic distortion of memory over an extended period are the defining characteristics of the hindsight bias. Becoming aware of an outcome causes people to revise implicitly their beliefs making it impossible to remember the beliefs they held before learning the outcome. Consequently, the individual overestimates the predictability of past events.  This is known as the hindsight bias (McGlynn, 2000).

This anecdote exemplifies the impact that knowledge of an outcome in a situation has on our judgment.  If the hindsight bias can influence student’s predictions of a trial, how then, does this phenomenon affect the decisions of jurors and judges in legal decision making? In this paper, I will go into more detail about the origin and definition of hindsight bias as well as the causes of the bias and how it affects legal decision makers in the courtroom. Furthermore, I will explore whether or not judges and jurors can avoid the hindsight bias. Finally, I will examine ways to reduce hindsight biases in the courtroom.

   Fischhoff (1975) was the first to conduct research on the hindsight bias by demonstrating the tendency to change a recollection from an earlier thought to something different due to newly provided information. Fischhoff (1982) explained the bias as an individual exaggerating what could have been predicted in foresight. The view the situation as being inevitable before it happened. They also believe that others should have anticipated the events better than they did in the first place.

Fischhoff (1982) was the first to test the hindsight bias in a study with undergraduate subjects. He gave his subjects a description of a nineteenth-century war between the British and the Nepalese Gurkhas, which included four different outcomes. The results included a British victory, a Gurkha victory, as well as a stalemate with and without a peace settlement. Fischhoff split the subjects into five conditions in which the materials either stated that one of the four possibilities occurred or information was not provided about the actual outcome. Fischhoff asked the participants the following question: “In light of the information appearing in the passage, what was the probability of occurrence of each of the four possible outcomes…” The subjects that Fischhoff informed that one of the results had occurred gave inflated estimates of the likelihood of that result compared to the subjects who did not receive any information about the outcome. To further test the hindsight bias, Fischhoff also provided a group of participants with an outcome and asked them to predict the possibility that other subjects, who were unaware of how the events unfolded, would have assigned to each possible outcome. This task consciously required the participants to attempt to see the world through the eyes of those who were not aware of how the events unfolded, despite the fact that the participants themselves did know. Fischhoff discovered that the participants were incapable of doing this because they were victims of the same biased assessment of what was predictable, similar to the subjects in the first study. Many researchers find this phenomenon worth studying and have duplicated studies such as Fischhoff’s using “I would have predicted it” and “I did predict it” methods (Rachlinski, 1998).

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