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Donald Trump and Scott Walker, the two Republican presidential candidates who have done the best job gobbling up recent headlines, are pretty different. One is an up-and-coming young conservative whose time as Wisconsin governor has left, depending on who you ask, either a devastating or an impressive imprint on the state. The other, a big-city billionaire, has no political experience but does have a long history of running and almost-running for president.

Despite their differences, though, the two candidates do have one major characteristic in common: Both proudly tout their go-it-alone style of leadership and decision-making. As Walker “prepares for his formal entry into the presidential contest,” wrote the Times a couple of weeks ago, “he has brought on a campaign manager, a pollster and a group of press aides. But he has not hired a strategist — because it might be needlessly duplicative: Those who know him well say that Mr. Walker has always been his own.” As the article notes, Walker is well known for micromanaging aspects of his campaign that most other candidates would delegate to others, to the point where there are worries that “[his] penchant for veering off into the arcana and mechanics of politics can divert him from his message[.]”

As for Trump, a recent Times headline says it all: “Who Advises Candidate Trump? (Hint: His Name Is Donald).” Trump’s lack of help on this front has been notable. It’s unlikely a candidate with a close coterie of advisers would have said that undocumented Mexican immigrants are rapists or would have revealed Lindsay Graham’s cell-phone number at a speech, as he did yesterday. He comes across as a candidate who does what he wants, for better or worse.

In the abstract, it’s easy to see how publicly advertising an “I’m the decider” approach might appeal to a certain type of voter, especially in a country with as ruggedly individualistic a political culture as the U.S.’s. But does this style of leadership translate to good decision-making? The answer, drawn from decades of research in organizational and personality psychology, is a resounding no.

Art Markman, an organizational psychologist at University of Texas at Austin, explained that humans, even very smart ones, have some serious natural limitations as decision-makers. We’re quite prone to various biases that cause us to miscalculate odds; pay attention to shiny, attention-getting pieces of useless information while neglecting more important but under-the-radar stuff; and so on.

These limitations hit hardest when we’re forced to make decisions in domains with which we’re unfamiliar — exactly the sorts of decisions a president has to make. “If you’re running for POTUS, you’re expected to be an expert in everything, and you can’t be,” said Markman. In other words, certain people can do a good job of making certain types of decisions on their own (you could do worse than asking Bill Belichick to call a game-deciding football play for you, even without an offensive coordinator advising him), but even someone with genius-level intelligence is unlikely to have the expert-level grasps of microeconomics and macroeconomics and foreign policy and environmental policy and all of the other subjects whose mastery would be required in an effective committee-of-one president.

But besides the expertise issue, there are other important reasons why, as a leader, having a team advising you is important — reasons that have to do with jelly beans. Well, specifically with those contests in which you have to guess the number of jelly beans in a container. A long line of research — decision scientists have actually studied jelly-bean contests for a century — has shown that when you average together the guesses of a group of participants, you get a lot closer to the true number of jelly beans than you would by picking any one individual guess, at least in most cases.

That’s because, while some people will guess too high and others will guess too low, taking an average can smooth out these errors, harnessing the so-called wisdom of crowds. Presidents don’t spend a lot of time guessing the number of jelly beans in a jar — well, with the exception of Reagan, maybe — but they do have to make decisions about troop levels and proposed tax rates and a million other decisions in which it’s hard to know what the “right” answer is, simply because the underlying issues are almost unimaginably complex. And a good president will take advisers’ views into account, adjusting his or her own preferred policy accordingly.

Unfortunately, according to Rick Larrick, a management professor at Duke University’s Fuqua School of Business, people have a natural tendency not to weight other people’s estimates as heavily as they should. He and his colleagues have observed this in a number of jelly-bean-style experiments in which they asked someone to predict a given value, but also provided them with an estimate produced by another group of people.

Imagine, for example, that a researcher asks you to guess the temperature today, and you say 85 degrees. Then the researcher says, “We gave five other people the same task, and on average they said 90 degrees.” The sensible thing to do, at least if you’re well read on research conducted by the Larricks of the world, would be to revise your guess upward. And in this situation, people often do that — they just don’t do it enough. There’s “20 years of research showing that on average people move a little bit near the judgement of others,” said Larrick, “but not anything near 50/50.” In addition, Larrick said he and colleagues have discovered that about half of all people don’t adjust their guesses at all — “They just stick,” he said. “That’s essentially the Donald Trump claim: I don’t listen to other people, deliberately.” It’s just another version of that most universal of human weaknesses: overconfidence in one’s own abilities.

So on the listening-to-advisers front, what separates a Donald Trump from, say, an Abraham Lincoln — a president who was famous for having a cabinet stocked with political opponents who could provide him with perspectives he might otherwise overlook? Lots of things, of course, but personality can be a big factor. Markman said that of the so-called “Big 5” personality traits — neuroticism, extraversion, conscientiousness, agreeableness, and openness to experience — it’s openness to experience that’s most tightly connected to a tendency to listen to others. He explained that the more open to experience you are, the more likely you are to at least respectfully hear out advice given by others, even if you don’t end up taking it.

I asked Markman whether, all things being equal, we should seek out leaders who are high in this personality trait. “Absolutely,” he said, “because the future is always different from the past, and if you believe you’ve got it all figured out because of what you’ve already done in your life, then you’re gonna miss important new pieces of information.” Be wary, in other words, of candidates who highlight past successes as proof of their universal decision-making prowess.

Now, none of these interactions between personality and situation occur in a vacuum — being a powerful person means receiving cues that you are a powerful person, and these cues can feed back into your sense of yourself as a powerful person who doesn’t need to listen to others. In fact, in lab settings, at least, “If you prime people to make them feel powerful, they’re less likely to take advice,” said Larrick. Francesca Gino, a professor of business administration at Harvard Business School, said in an email that she’s conducted research that suggests a reason why. “I found that powerful decision-makers tend to resist the advice of experts because they experience the advice as a threat to their own claim to power and feel competitive with their advisers,” she said. This notion fits with the idea that “Donald Trump and Scott Walker take pride in being their own advisers and not really taking a lot of advice from others.” Larrick offered a similar interpretation: “One way to kind of exert your power is to stick by your opinions, no matter how wrong they are.”

What’s interesting about all this research is just how broadly applicable it is. No one can predict what challenges a given president (or CEO, or school-system superintendent, or … ) will face, but there are some pretty clear-cut rules to making good decisions once one is in power, and none of them is rocket science: Don’t overweight your own views. Have smart advisers. Listen to those advisers.

Maybe if Scott Walker or Donald Trump becomes president, they’d internalize some of these lessons. But based on what we’ve seen so far on the campaign trail, it seems more likely they’d go their own way — and do so proudly.