During the candidate debates this month, one of the questions that television viewers will ask themselves is whether Barack Obama or Mitt Romney has the right stuff—Does either man appear "presidential"? The two will communicate their answers, not just by anticipating and parrying their opponent's critiques or demonstrating a grasp of policy and sensitivity to voter needs, but also via subtle gesturing before the camera and, perhaps most of all, through an unflinching coolness under pressure.

Questions about presidential caliber will not end after the debates or even the election is over. Off camera, the mix of personal attributes that makes someone fit for executive stewardship of an entire nation has always come under the intense scrutiny of historians—and more recently psychologists. The search for the ineffable quality that makes for greatness has in recent years led to an examination of a personality characteristic that is more closely associated in the public mind with an inmate at a federal penitentiary than an occupant of the White House.

Scott Lilienfeld, a psychology professor at Emory University, published in September a study in the Journal of Personality and Social Psychology that applied a measure used to assess psychopaths—"fearless dominance"—to the performance of every U.S. president through George H. W. Bush—sufficient data was not available to assess Obama or Romney.

[An edited transcript of the conversation with Lilienfeld follows.]

What did you find in your study?
What we found is that when we consulted experts and biographers of every U.S. president, along with a wealth of historical material, we were able to extract some estimates of those traits relevant to psychopathic personality.  We turned up one specific subset of traits that are part of psychopathy. Fearless dominance, or something very similar to boldness—seems to be related to better presidential performance across the board, particularly in the interpersonal arena. So bold presidents—those who seem to have low levels of physical and social fear, those who are emotionally resilient, those who are perhaps a bit daring—were typically rated as more successful presidents. They were rated as more persuasive at handling crises and appeared to be more effective at a number of independent indices.

How did you determine all of this?
Steve Rubenzer and Tom Faschingbauer [both historians] collected the original data quite some time ago. With a lot of help from them, we were able to get access to living biographers and experts on every U.S. president, with partial funding from the National Science Foundation. I was initially surprised that there was a living biographer of Millard Fillmore. But that's academia for you. We know more and more about less and less, right?

These people spent years and years, if not decades, studying these presidents. They all filled out for us a very, very long battery of questions, and using nifty statistical formulas we were able to estimate presidential scores on various dimensions relevant to a psychopathic personality. We have good estimates on how they scored on these measures including, but not only, fearless dominance

Would you say that any good president is a partial psychopath?
I would say boldness is a part of psychopathy. But I would not feel comfortable saying someone who is high in boldness is a partial psychopath. We see psychopathy as a configuration of three dimensions—boldness, poor impulse control and self-centeredness—that go together. Someone's not a prototypical psychopath without all three of these traits. So we would not see someone high in boldness as sort of psychopath.

Who came out on top in boldness?
It's interesting to see that the ratings line up with what we know about presidents. Theodore Roosevelt was our highest scorer on fearless dominance, and that fits a lot of what we know about him. One historian writing in The New York Times said that he would walk into the room and suck all the air out of it. Roosevelt did not score high on the other measures of psychopathy, though.

Were there any surprises?
For me, I was a little surprised that Truman wasn't ranked higher for his office. I would have put him in the top five. I think he was above average, but he wasn't as high as I would have anticipated

Why is it interesting to approach this question from the standpoint of psychopathy as a whole and not just look at "fearless dominance" per se as a singular trait?
If you're asking: Might one have arrived at the same conclusions if one hadn't started with psychopathy—using physical and social fearlessness alone as the best predictor?—I think the answer is yes. The point we would make is that these findings bear implications for psychopathy in general. In the business world people assume that psychopathy at large is undesirable in a job candidate, something you wouldn't want to have any of.

So this work implies that if we eliminate psychopathy entirely, including boldness, it might not be such a good thing; I get this question a lot because I developed a measure of psychopathy. People ask me: Can we use this measure to screen out people for law enforcement, police, fire, military? I think this finding bears the implication that if you look at this in its totality, that might not be so good in the domain of leadership.

If a candidate has the trait of fearless dominance, don't you also have to consider whether there might be negative traits of psychopathy as well?
Absolutely. All things being equal, a dash of boldness facilitates presidential success. Very often things are not equal so we have to consider other aspects of psychopathy, too. Traits of psychopathy linked to poor impulse control and self-centeredness were not related to better presidential performance and in some cases they were related to worse presidential performance.

Should we care a lot about all of this in electing a president?
My own feeling is that we shouldn't. We probably overestimate sometimes the importance of things like likability and how much we would want to go out and have a beer with a person. To me, the more interesting part of the study is using presidents as a vehicle for understanding boldness in the role of leadership in general.

Illustration by: Ryan Reid