I knew it all along! But did I? - Hindsight bias in negligence cases

Updated: Jan 24

When people evaluate events or outcomes after they have occurred, they tend to exhibit the so-called hindsight bias: they judge the event as being more foreseeable than before it happened. As trials typically occur after some harm or damage has occurred, the judicial decision-makers of liability cases are highly prone to this ‘I know it all along’ phenomenon. A study conducted in a legal setting shows that judges with outcome knowledge perceived the occurred harm as significantly more foreseeable, which led to a more frequent affirmation of negligence.

The phenomenon of hindsight bias is a well-studied cognitive illusion with the tendency to overestimate the foreseeability of an outcome once it is known. Precisely, hindsight bias consists of three different components that are the increased perceptions of inevitability ("It must have happened"), the increased perceptions of foreseeability ("I knew it would happen"), and the memory distortions ("I predicted that it would happen").

This bias has severe implications for decisions made within the legal system, ranging from investigations to court proceedings. Damage case judgments are based explicitly on the decision-maker's evaluation of how foreseeable the harm was. Crucially, the judges review these cases with full knowledge of a negative outcome which can easily activate the hindsight bias and affect their judgments about what was knowable in the past.

Oeberst and Goeckenjan (2016) designed an experiment to investigate the impact of outcome knowledge in negligence judgments of judges. Altogether, 84 German judges (44 female, 36 male, four without specification) participated in the experiment.

The researchers presented a negligent case (based on an actual legal case) to the judges either with or without the outcome and asked them for their perceived foreseeability of the outcome as well as for negligence judgments. Subsequently, the participants were asked for the perceived foreseeability of some harm in general on a 5-point scale. For the hindsight condition, the question was posed in the past tense. Additionally, participants were urged to ignore the outcome when answering the question. The judges were then presented with four alternative outcomes (two positive outcomes without any harm, two adverse outcomes with harm/damage) of the event and were asked to rate the perceived foreseeability of each outcome on the same 5-point scale as above. Again, judges in the hindsight group were asked to ignore the actual outcome. Lastly, the participants were asked to judge the breach of duty of care of the allegedly negligent person's behavior on a 5-point scale as well as negligence (yes/no).

The experiment results show that judges with outcome knowledge perceived the occurred harm as significantly more foreseeable, which in turn led to a more frequent affirmation of negligence. The effect of outcome knowledge on foreseeability evaluations resulted in biased negligence judgments: twice as many judges in the hindsight condition affirmed negligence (30%) compared with those in the foresight condition (14%). The perceived foreseeability of the harm mediated this effect of outcome knowledge on negligence judgments. The researchers also concluded that hindsight bias is not an intuitive error that deliberation can tackle. Instead, hindsight bias can be reduced by specific types of deliberation, namely the consider-the-opposite technique.


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When Being Wise After the Event Results in Injustice: Evidence for Hindsight Bias in Judges’ Negligence Assessments


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