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.