Mental Heuristics in the Courtroom: Where Judgement and Justice Meet Science

By Diya Basra

In a courtroom, neurons fire at high rates for each decision made – from the jury deciding their verdict on a defendant to the judge deciding the defendant's sentence. While the legal system theoretically operates under logic and rationality, the people operating within the system don’t always function this way, often relying on mental heuristics.

While our brains approach some situations with step-by-step, algorithmic decision-making, psychologist David Kahneman states that we also use mental heuristics, or general rules of thumb, in order to reach solutions more efficiently (Frimodig, 2023). These general rules involve both the prefrontal cortex and the limbic system, which are related to cognitive control and emotional processing (Tomorrow Bio, 2023). Realistically, we can’t process every piece of information around us and painstakingly compute the value of all possible outcomes, especially for the frequent, low-stakes choices we face daily. So, heuristics relieve a burden, easily allowing us to decide on what to wear in the morning or where to get dinner on weekends.

While heuristics work well in low-stakes situations, providing “good enough” solutions, they still leave room for error and inaccuracy that have greater consequences in high-stakes situations (Pilat & Krastev). Relying on heuristics means we aren’t using the most logical decision making path to make a decision, and we risk undervaluing important information while overvaluing unimportant information. Especially with repeated use over time, our brains form a habit of relying on heuristics. This habitual behavior is linked to a connection system in the brain called the corticostriatal sensorimotor loop, which connects parts of the brain involved in sensory processing, motor control, and skill learning (Mendelsohn, 2019). When we are used to thinking quickly and automatically, which Kahneman proposes as a system 1 way of thinking, then we are more likely to rely on this way of thinking, especially in stressful situations (Pilat & Krastev). While this way may feel easier, it can come at the cost of fair and accurate thinking, especially in a legal context. On the other hand, if we are aware of our habits and the ways we may unnecessarily rely on heuristics, we can break out of them and into what Kahneman proposes as as a system 2 way of thinking, involving more conscious and complex reasoning (Pilat & Krastev). Goal directed behavior opposes habitual behavior, and is linked to a connection system in the brain called the associative corticostriatal loop, connecting areas in the brain involved in decision making and impulse control. If we are able to engage this connection more, we can control our instincts to take the easy way out. According to Kahneman, the two systems exist to complement each other, so we need to ensure we apply a balance of both, especially when justice is at stake (Pilat & Krastev).

David ​​Kahneman and Amos Tversky identified three main heuristics: the availability heuristic, the representative heuristic, and the anchoring and adjustment heuristic (Pilat & Krastev). Using the availability heuristic, we judge how likely an event is to happen based on how easily examples come to mind (Pilat & Krastev). So, if we often see crime on the news, we may believe crime rates are higher than they are. The fact that our brains are more likely to remember emotionally charged information such as crime contributes to this belief (Kensinger, 2009). As a result, jurors may be more willing to punish a defendant during trial, and lawmakers may advocate for harsher policies. When left unnoticed, the availability heuristic leads people to make unfair judgements based on information that an individual happens to recall rather than based on a broader, more holistic perspective. 

Using the representative heuristic, we categorize events or objects based on their relation to what we are already familiar with (Pilat & Krastev). This causes us to make  predictions about situations or people using these categories. The representative heuristic most strongly demonstrates how stereotyping and profiling work. In a legal context, a juror could wrongly assume a defendant is guilty based on many characteristics they group within a certain category such as their clothing, race, or accent. Dangers lie in the fact that the representative heuristics allows external, societal factors to impose on the rational integrity and statistical nature of an individual case, where prejudice may lead the way to unfair punishment.

Finally, the anchoring and adjustment heuristic allows us to estimate certain values quickly, calculated according to an initial value (Pilat & Krastev). Here, even though the initial value makes it easier for us to kickstart our estimation process, our final estimate will inevitably remain anchored to that starting point in relation to the actual value we are trying to find. In the situation where a prosecutor begins with a harsh initial charge, the defendant and their lawyer use that number as a starting point during the plea bargaining process. As a result, defendants may accept harsher plea deals than they would have if the initial charge were lower. 

Understanding mental heuristics provides significant insight to the complex yet intriguing ways our brains make decisions and save both time and energy with each one. However, understanding the risk of using these heuristics in legal situations where our own conscious, critical thinking should be applied instead allows us to keep them in check and take control of our own decisions. Especially for lawyers and policymakers, who have a responsibility to contribute to and create a just legal system that fairly serves everyone, it is necessary to maintain the sense of logic and rationality by which the system is designed to operate.

References

By, Frimodig, B., on, U., 24, O., & Expert  B.A., B. Frimodig  Science. (2023, October 24). Heuristics in psychology: Definition & examples. Simply Psychology. https://www.simplypsychology.org/what-is-a-heuristic.html

Kensinger, E. A. (2009). Remembering the details: Effects of emotion. Emotion Review, 1(2), 99–113. https://doi.org/10.1177/1754073908100432

Mendelsohn, A. I. (2019). Creatures of habit: The neuroscience of habit and purposeful behavior. Biological Psychiatry, 85(11). https://doi.org/10.1016/j.biopsych.2019.03.978

Pilat, D., & Krastev, S. (n.d.). Heuristics. The Decision Lab. https://thedecisionlab.com/biases/heuristics

Tomorrow bio 4.0. (n.d.). https://www.tomorrow.bio/post/decoding-heuristics-unraveling-the-power-of-mental-shortcuts-2023-06-4732193904-rationality#:~:text=The%20Neuroscience%20of%20Mental%20Shortcuts,of%20options%20when%20employing%20heuristics