Judges are far more likely to let a prisoner out on parole if they've just had a food break than if they've been considering cases for hours, according to a new study.
Researchers don't know if it's the food or the mental breather that makes rested judges more lenient after their breaks. But the findings suggest that judges are like the rest of us: After making a series of difficult decisions in a row -- about anything from which features to get in a new car to the details of a home-renovation project -- our tendency is to pick whatever the easiest option is.
The study also shows that facts and laws aren't the only issues that affect legal decisions. And chances are, the same phenomenon affects doctors, members of Congress, university admissions officers and other people who make important but repetitive decisions.
"This is a necessity of the human condition: You get tired and you have to replenish," said Jonathan Levav, an expert in the psychology of judgment and decision-making at Columbia Business School in New York. "It's important for people to understand that legal decisions and human decision-making are one and the same."
"There's no reason to believe that biases that affect us in our everyday decisions won't affect decisions in experts," he added. "These are people, too. They're not machines."
In previous work, Levav had probed the mental fatigue that builds in people as they shop for cars or new suits. After test-driving dozens of models of automobiles with a variety of engines, colors and other features, he said, he has found that people simply don't feel like making decisions anymore. Eventually, they tend to go with whatever radio comes with the car. Worn-out clothes-shoppers, likewise, will eventually just grab whatever's on sale or available now.
He started to wonder if the same thing could be happening in weightier situations. So, for the new study, Levav teamed up with colleagues at Ben Gurion University of the Negev in Israel. The researchers compiled more than 1,100 judicial rulings made by eight Israeli judges with an average of more than 22 years of experience. All of the cases involved requests for parole by prisoners.
From court records, the researchers could clearly see the time of day each case happened and the order in which decisions were made. The researchers also knew exactly when judges declared food breaks. After analyzing cases based on all sorts of factors, including severity of the crime and outcome of the case, they discovered a strikingly clear pattern.
At the beginning of the workday and right after both of two daily food breaks, judges ruled about 65 percent of cases in favor of the prisoner, the researchers report today in Proceedings of the National Academy of Sciences. But by the end of each session, the probability of a favorable ruling was close to zero. In these kinds of cases, leaving a prisoner in jail is the easiest decision to make because it simply maintains the status quo.
"Once you see the plot, it's almost like you don't have to do any statistical tests," Levav said. "As judges consider more and more cases, their likelihood of releasing prisoners decreases. But when they take a break to have a meal, that likelihood pops up to its original levels. It's almost like the judges have mentally reset."
Any finding that reveals unexpected patterns in professional decision-makers needs to be taken seriously, said David Schkade, a decision researcher at the University of California, San Diego's Rady School of Management.
Pilots and air-traffic controllers already take frequent and regulated breaks because it is well known that they become mentally depleted after conducting a series of repetitive tasks. The new work suggests that judges and possibly other professional decision-makers might do well to follow similar guidelines.
"This is a really surprising and important result," Schkade said. "Despite their professionalism, judges still get tired mentally."
As for whether the newfound bias makes judges most accurate when they're at their most strict or at their most lenient, that's something Levav and colleagues are trying to find out. They're mining through nearly nine years of data, looking at which prisoners ended back up in prison after their release and correlating that information with how close to a food break their case was heard.
"That's the multi-billion-dollar question," Levav said. "What's the cost of this bias?"