Improving Jury Deliberations Through Jury Instructions Based on Cognitive Science

Note: This article was originally published by the American College of Trial Lawyers.

With this closing instruction ringing in their ears, jurors across the country are sent off to their deliberation rooms to reach a verdict:

“Free your minds of all feelings of sympathy, bias and prejudice and let your verdict speak the truth, whatever the truth may be.”

For decades we believed this instruction was effective and its goals attainable. People could simply “free their minds of all feelings” and reach a verdict based on reason and objective facts—or so we thought.

Recent advances in the science of decision-making, however, undercut our assumptions about how jurors make decisions. Science now teaches that our cerebral cortex (and its deliberate, logical power) does not either solely or separately rule the day. Instead, logic or reason (described below as “System 2” thinking) operates alongside and in conjunction with the evolutionary brain and its quick, instinctual impulses (described below as “System 1” thinking). Thus, instructing someone simply to shut down part of their brains and “free their minds of all feelings . . .” is as effective as telling a child perched on a garage roof to ignore gravity.

Nobel Laureate Daniel Kahneman is among the leaders in the developing understanding of human decision-making. Kahneman and his colleague Amor Tversky relentlessly challenged the received wisdom that human beings are motivated to—and do—routinely make rational, logical decisions. Kahneman summarized his and Tversky’s work in the 2011 best seller, THINKING, FAST AND SLOW. This book brings to the general public a lifetime of cognitive and social psychology research about the many non-rational ways that human beings make decisions—including the multiple ways we predictably and without awareness commit errors in logic and reasoning.

Jonathan’s Haidt’s book, THE RIGHTEOUS MIND: WHY GOOD PEOPLE ARE DIVIDED BY POLITICS AND RELIGION (2012), likewise pulls back the curtain of myth and misunderstanding to show how humans actually make decisions. Haidt uses the tools of neuroscience and social psychology to explain how humans’ intrinsic moralistic, judgmental nature is moved by forces that operate more through rapid intuitive judgment than through careful “reasoning why.” Like Kahneman and his Systems 1 & 2, Haidt likewise differentiates between two types of thinking, one that is conscious (reasoning) while the other operates intuitively.

This paper first summarizes the core insights of Kahneman, Haidt and other scientists into common flaws in human decision-making. Next, Part 2 discusses recent efforts by courts to improve jury instructions about the dangers of eyewitness identifications by taking account of (and trying to offset) flaws in human decision-making. Then, Part 3 offers several model jury instructions based on the science of decision-making that are designed to counter cognitive flaws and focus jurors’ attention, increase their use of deliberative thought, mitigate “confirmation bias,” and broaden participation during jury deliberation.

The goals here are straightforward: to increase the thoroughness of jurors’ evidence review and to improve jurors’ deliberations. The premise is that jurors who focus and deliberate in a meaningful way are more likely to reach the correct decision. Ideally, this paper responds to Professor Burns’ request for cognitive science insights to help improve jury trials:

I would like to see a sustained attempt by experimental psychologists and other social scientists to identify those systematic failures in human cognitive capacities (heuristics) about which there is the highest level of certainty in the scientific community and which pose special dangers of distorting jury reasoning.

- Robert P. Burns, The Death of the American Trial (2011).

Part 1: Cognitive Science Insights into Human Decision-Making

The core concept captured in the title of THINKING, FAST AND SLOW is that our brains are wired so that they reflexively default to fast, intuitive thinking—what Kahneman calls “System 1” thinking—instead of using slow, deliberate “System 2” thinking, which requires more effort but is better suited to working through complex and difficult issues…