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The Illusion of Explanatory Depth and the Presentation of Expert Evidence

Mary Catherine Way and Lauren Grinder

The Illusion of Explanatory Depth and the Presentation of Expert Evidence
Heide Benser via Getty Images

Even if you’ve never heard the phrase “illusion of explanatory depth” (or IOED), it is a challenge you’ve likely faced if you’ve presented complex scientific or medical evidence to a jury. Yale researchers conceived the term to describe their observation that, especially when people initially hear an explanation, “[m]ost people feel they understand the world with far greater detail, coherence, and depth than they really do.” Leonid Rozenblit & Frank Keil, The misunderstood limits of folk science: an illusion of explanatory depth, Cogn Sci. 26(5): 521-562 (2002). The researchers asked participants to rank their understanding of how certain items (including helicopters and zippers) worked, to write a step-by-step causal explanation, re-rate their understanding, and then compare their understanding to an expert description. Importantly, though participants had less confidence in their knowledge after having to explain how each of the items worked, they felt their knowledge increased “dramatically” after reading the expert explanations. Id. The researchers proposed that “knowledge of complex causal relations is particularly susceptible to illusions of understanding.” Id. at 2.

Why is this relevant to the presentation of expert evidence to a jury? An overconfident juror operating under the IOED will likely share (convincingly!) their inaccurate understanding of the evidence with other jurors, making it crucial to equip jurors with the right questions to ask during deliberations to expose flimsy reasoning as well as providing them with answers for the weakest parts of your narrative.

The following are three practical ways to combat the IOED as you consider the presentation of expert evidence to a jury:

  1. Clearly show the jury what your opponent’s expert had to ignore in order to reach their conclusion. In favor of clarity over complexity, the jury has likely heard an apparently simple explanation for a rather complicated outcome in the case. This explanation was probably accompanied by just enough scientific rhetoric to make a jury feel like it has more than enough information to understand the issues presented in the case. Your job when you stand up to cross-examine the expert is not only to, depending on the case and the expert, call into question the expert’s qualifications, emphasize where the expert agrees with your expert (and facts favorable to narrative), and expose problems with the expert’s methodology, but to also show the jury what the expert had to ignore (or at least rule out) in order to reach their conclusion. This is easiest to illustrate when there are multiple potential causes for an injury. What causes did the expert rule in (or should have ruled in) and what did the expert do (or not do) to rule those causes out? A well-organized cross-examination may serve to confront the overconfident juror with the reality that they may not actually understand the subject as much as they thought and, more importantly, equips other jurors with the right questions to counter the overconfident one with information that supports your position in the case.
  2. Use your expert to combat the “Dr. Google” mindset. In a world where each juror sitting in the box has likely relied on their own googling for self-diagnosis, you must show them why they should listen to your expert. This is more than just going through your expert’s education and experience as a matter of routine to establish they are qualified under the rules to give their opinion. This is emphasizing the depth of your expert’s knowledge and why that depth of knowledge matters to the particular issue the jury needs to decide. Your direct examination should demonstrate to the jury that your expert has a clear understanding of the complex issues in your case. You can do this by asking questions that demonstrate (1) why your expert is uniquely situated to speak directly to the key issues in the case and (2) the depths of your expert’s understanding. This simultaneously shows exactly what those overconfident jurors suffering from IOED do not know while building confidence in your expert.
  3. Lay the groundwork for the jurors in your camp to convince the rest. This requires equipping jurors with answers to the hard questions that involve the weakest parts of your narrative. This may be a factual question outside the expert’s purview, but it may also be a question of science or medicine that your expert must answer. Additionally, it could be a matter of providing a framework for certain evidence, like using the advancement of technology and science over time to explain a decision to withdraw a certain product from the market. In whatever ways the expert intersects with the hard questions, consider carefully how to present the jury with answers. This will aid your jurors during deliberations.  

While it is no surprise that people tend to overestimate their own knowledge, especially in today’s world where deceptively simple explanations for complex phenomena abound on the internet, it is a reality trial teams should not forget in the presentation of expert evidence.