Whether you’re a surgeon, a Supreme Court justice, or none of the above, decisions are an integral, unavoidable part of daily life. When the necessity of decision-making enters the judiciary, hospitals, and businesses, it’s especially crucial to survey the ways leaders arrive at their conclusions to unearth the hidden influences that disturb seemingly impartial results. In their newest work, Nobel Prize winning psychologist Daniel Kahneman and scholars Olivier Sibony and Cass R. Sunstein investigate the influence of “noise,” diagnosing dissonance in our decision-making and encouraging us to conduct choices that resound with greater harmony.

Do you find yourself easily frustrated on humid days, or especially gracious after lunchtime? While tiny details of daily life may seem inconsequential, studies prove that they aren’t as harmless as they may appear. Often, these minor considerations maintain a crucial role in decision-making. And they turn potentially destructive when judges, doctors, and other leaders are the ones calling the shots. The authors define this kind of “noise” as small but corruptive interferences within decision-making that lead to wide-ranging oversights. Noise tampers with an individual’s ability to come to fair conclusions, and it can be highly raucous—it’s rarely ever seen and hard to attribute to a single cause. 

Take the case of the judicial system, one of the more impactful areas of decision-making. Compelled by the inconsistencies he witnessed inside the courtroom, the renowned Judge Marvin Frankel voiced his concerns throughout the 1970s, publishing a book of his findings entitled Criminal Sentences: Law without Order. Frankel’s indictment of the justice system propelled reams of studies throughout the 1970s and 80s, many of which discovered something awry in federal judges’ administration of seemingly neutral sentences. In an evaluation that took place in 1981, experimenters allotted identical cases to judges in order to discern unnecessary discrepancies in their decisions. Unfortunately, the experimenters found some pretty bad news for anyone approaching the cold, towering doors of a courtroom. 

Though each of the judges received the same information as their peers did, in most cases, the conclusions they drew were vastly different. Not only did each of the judges come to completely irreconcilable judgments from the same case material, but they issued disparate sentences too, anywhere from 8.5 years to life in prison. These extreme discrepancies garnered a lot of attention.

Thankfully, the sentences in the 1981 experiment were only test cases, but the research grew even more terrifying when these same trends were uncovered in real, everyday courtroom scenarios. A comprehensive 30-year study of 1.5 million judges showed a disturbing correlation between negative outcomes of recent local football games and stricter trial sentences. Evidently, a regional team’s game-day blunder took a steep toll on people in the courtroom thereafter. If you do have to pay a visit to your local judge though, you may want to do it on your birthday. A large study from France proved that when a trial date landed on a defendant’s birthday, she was more likely to receive positive news from the judge—a courtroom birthday gift even more welcome than a cake covered in candles.

Though the noise beneath our decision-making can be difficult to hear, its influence is obvious when researchers look at the evidence. These instances of decision interference can be silently detrimental, corrupting systems that are designed to be equitable in all circumstances at all times—even if it isn’t a defendant’s birthday.

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Noise abounds in both the most minute and the most influential spheres of judgment. After all, no person is a soundproof command center, executing seamless choices freed from outer influence and inner misconception. And yet, this unavoidable interference seems almost nonexistent to decision makers for various reasons. According to the authors, reality appears to people as a string of causes and effects. Noise, on the other hand, is more statistical in nature, making it more difficult to grasp. When researchers apply a more statistical analysis to the process of decision-making, assigning numbers to the noise, they can listen to its volume and learn to distinguish its incongruous sounds.

Another 1981 “noise audit,” or an examination in which many people address parallel decisions, reveals the content of disruptive noise. Seeking a more definitive analysis of decision interference in the judicial system, researchers gathered a group of 208 judges and presented them with 16 individual cases. Calculating the judges’ responses, the researchers found a high degree of noise within the cases. They determined that the “mean absolute difference,” a statistical term that denotes the average disparity between any two given sentences, was nearly four years. In other words, the particular judge presiding over a case plays a crucial role in determining the outcome of the rest of the defendant’s life.

Beyond this finding, the researchers also identified the various parts of “system noise,” to which the authors give explanatory labels. Each of these functions contributes to noise’s ability to jilt decision-making, and they’re often shockingly elusive. “Level noise,” for instance, concerns the unique perspective of a particular judge, doctor, or decision maker, often due to factors such as belief, upbringing, and political orientation. Interestingly, the study showed that a judge’s perception of the role of prison impacted his conclusion as well, with those who favored “rehabilitation” as a primary aim granting prisoners less time behind bars. The authors write that this kind of noise “functions like a personality trait”—a rather troubling conclusion for those who find themselves on the other side of a judge’s bench.

Just as judges are unavoidably different from one another, their inner dispositions on any given day vacillate as well. The authors identify this kind of disruption as “pattern noise,” and it signals a judge’s departure from her ordinary sentencing behavior. In this context, pattern noise may seem self-explanatory and even necessary—a judge should respond differently to the unique cases brought before her, right? But oftentimes, pattern noise is permeated by another kind of sound: “occasion noise.” This interference provokes differences in judgment of all kinds due to factors that typically have nothing to do with a particular question. The way a person feels, personal issues, and even the weather stir up occasion noise and lead to results that don’t reflect the reality of a particular situation.

When level noise, pattern noise, and the sly occasion noise build on top of each other, a precariously slanted structure rises into view—one we can’t see easily with our own eyes, but must use a lens of statistics to detect.

What happens inside the human brain when it’s faced with a particular decision? Whether that choice concerns prison sentencing, medical diagnoses, or the minutiae of daily life, our brains place each of us on a fast track of decision-making. In his previous work Thinking, Fast and Slow, Daniel Kahneman discusses the tendency for the human brain to slip into what he terms “System 1 thinking,” which compels people to use “heuristics” to form oftentimes inaccurate assumptions. Like a backroad shortcut on a long road trip, heuristics typically expedite the process of thinking. But just as shortcuts often lead drivers astray, heuristics also point thinkers toward faulty “psychological biases.”

Various biases pervade human thought, clanging our cognitive cymbals and producing a disharmonic noise. Consider “conclusion bias,” for instance. This bias moves people toward predetermined ends, employing the brain’s lightning quick System 1 thinking to weaponize the mind. The human brain works hard to secure what it wants and contrives evidence to support its initial stances, even if those are perilously inaccurate. 

An especially fascinating example of a conclusion bias in action took place when an experiment’s participants took note of the final portion of their Social Security numbers. This might sound like a meaningless exercise, but when researchers followed the task with a couple of questions, a bias was revealed. When participants were later asked how much money they might spend on a bottle of wine, researchers found that those who wrote down higher Social Security numbers agreed to spend more. The authors call this trend the “anchoring effect,” and it predisposes the brain to employ a previous number in follow-up decisions. The brain uses readily available knowledge to alleviate the burden of decision-making (and prompt you to pay a high price for a basic bottle of wine).

A similarly impactful (though perhaps less expensive) bias called “excessive coherence” also compels the brain to use previously gathered information to build perceptions. Once again, the brain’s System 1 thinking flares into action when it engages with something for the first time, sketching an outline to contain and shape following decisions. Anyone who’s been to a fast-food restaurant recently has experienced the pull of this bias, maybe even beyond one’s conscious awareness.

According to one study of those frustratingly high calorie labels displayed in US fast-food joints, whether a customer decided to indulge in an unhealthy treat depended on the order of the product on the menu and the label. For most people, when the number was placed on the left, onlookers’ eyes wandered upon that devastating count before they even had a chance to develop a taste for that large order of fries. And with that shock rooted firmly in mind, restaurant-goers were more inclined to consider the calories before ordering.

Though each of these cognitive tendencies may bolster decisions in some cases, making the process less taxing and more fluid, they often cause biases that short-circuit thinking. When leaders foster their own distinct thought preferences, unaware of the capacity for the human brain to bend the evidence it receives, an unstable, fluctuating noise can hamper sound decision-making.

Nobody wants to be on the receiving end of another person’s blind mistake—especially when that person is a professional whose expertise you desperately need. Similar to judges, doctors play a vital role in individuals’ lives. The decisions they make are hugely influential, and unfortunately, they’re prone to a great deal of noise, too. Countless hospital studies show that diagnostic agreement among doctors isn’t as certain as their patients would like to think. Fortunately, the medical field has implemented various measures to silence the noise in these evaluations. Moreover, the authors recommend one of these methods as one element of their “decision hygiene” plan, a scheme that calls attention to hard-to-hear noise in order to squelch its clamorous influence.

Sometimes decisions seem overwhelming—they’re often filled to the brim with so many pressing details and bits of information for people to consider before making a choice. Such is the case in the medical field. Faced with a multitude of simultaneous considerations, it’s no wonder that hospitals ring with noise. One way physicians have learned to overcome disparate diagnostic decisions is through the creation of particular guidelines, a decision hygiene practice the authors recommend throughout their work. In 1952, a physician named Virginia Apgar developed the Apgar score, a directed and numeric evaluation of a newborn baby. Instead of every nurse attending to factors she herself considered as indicative of a baby’s health condition, each is now helpfully guided in the process through a predetermined rubric that gauges specific components such as a baby’s heart rate, reflexes, and breathing.

Taking a problem and investigating its parts individually leads to better informed decisions and less fluctuation in larger decision-making structures. The previously mentioned Judge Marvin Frankel witnessed the impactful success and the telling fall of these kinds of judgment guidelines when they were implemented by the Sentencing Reform Act of 1984. Under the auspices of the US Sentencing Commission, judges were prescribed clearer evaluative methods for determining sentences. After judges took this more prescriptive and less individualized approach to decisions, various studies showed that the judiciary experienced far less noise in sentencing.

Not everyone was happy with the hand-holding the government had forced upon judges, though. Kate Stith, a professor of law at Yale, and Judge Jose Cabranes argued that such an approach emptied the judicial process of its humanity, boiling people down to simple items on a checklist. In 2005, in response to increasingly pervasive discontent, the Supreme Court reissued the guidelines as mere suggestions. And as a result, noise shook the halls of the courtroom once again. When the Harvard professor Crystal Yang assessed the state of the judiciary after the guidelines were removed, she discovered that noise had returned in double time—without a clear outline for the judgment process, the range of sentences was abnormally large once again.

They may not be attractive, but guidelines often make decisions much more egalitarian. Judges and doctors definitely aren’t the only ones who need a little help with their judgment, though. Decision hygiene enables every person to think more clearly as a choice arises and develop a conclusion that best fits the evidence at hand. As the authors wittily remark, “There may not be much glory to be gained in hygiene, but there are results.”

The word “rules” doesn’t always fall nicely onto most people’s ears. As in the case of the judiciary guidelines, many people are apprehensive to adopt any kind of decision-making guidance that threatens their perception of free choice. To quiet judgment disruptions, the authors recommend both the institution of rules and the implementation of standards. On the one hand, rules streamline decisions but often create an oppressive mold that leaders like judges and doctors feel they must squeeze into. Rules eliminate vast amounts of noise, but leave people with far less room to exert their own individual choices (which might be beneficial, considering how muddled those can be). Standards, on the other hand, are less prescriptive, appearing more attractive to decision makers. But they are also more apt to echo with noise once again. Neither method is foolproof, and often, individuals and entities must ascertain what their field calls for and determine the appropriate route. 

When dealing with questions that concern the wellbeing of peoples’ lives—such as those made by doctors and judges—thoughtful rules may be the more influential route to correcting interference in decision-making. For instance, the “disability matrix” is a rule-based regimen that helps judges assess the particular disability status of an individual. Discerning a person’s level of disability in court is both highly impactful and dangerously ambiguous. The addition of rules, on the other hand, helps judges avoid potential pitfalls to execute fair decisions. Rules may not always be the most fitting answer in every scenario, but when they’re carefully considered in the realms of medicine and the judiciary, they may prove a powerful tool in orchestrating wiser decisions.

Deliberating a defendant’s prison sentence may not be on your daily agenda, but everyone can learn a little something from the fallibility of decision-making and how one might correct potential missteps. Growing aware of these slight interferences in the painstaking process of decision-making is crucial to remedying the issue of noise in personal and in public life.