RENTON, Wash. -- When Angela Duckworth returned to Philadelphia last May, friends and colleagues wanted to know who she had met during her visit to the Seattle Seahawks' practice facility.

Russell Wilson? Marshawn Lynch? Richard Sherman?

Unfortunately, Duckworth wasn't quite sure how to answer.

"I didn’t even know who the quarterback was," she said.

A professor of psychology at the University of Pennsylvania and MacArthur Fellow, Duckworth does know coach Pete Carroll. A few years ago, he reached out to learn more about an idea she is an expert on: grit.

In the football world, the term has most often been stereotypically used to describe the scrappy special-teams player who overachieves through great effort. Think "Rudy" or "Invincible."

But The Duckworth Lab at Penn focuses on predicting achievement. And Duckworth has a very specific definition of grit: the tendency to sustain interest in and effort toward very long-term goals. It is broken down into two categories: passion and perseverance.

"They go to Starbucks to buy a latte or they watch a movie or they have a conversation with a second cousin, everything that they see, that they do, that they smell, that they experience, becomes related to that one thing that they really are passionate about," Duckworth said.

"Perseverance, people often think about what happens when you break your arm or have this devastating loss, you miss a field goal, that kind of thing. The other quieter aspect of perseverance, which I think Pete also models, is the ability to do the deliberate practice that real experts do to get better."

Duckworth spent about an hour on the phone with Carroll and other members of the Seahawks' organization, discussing the concept. They talked about how to identify grit in a person -- whether it was something that could be developed, and how to build a culture that promoted it.

"His idea was, ‘Can a coach move people to some degree on either their passion for what they’re doing or their perseverance?'" Duckworth recalled. "His answer was, ‘Yes. I think to some degree a coach can create a culture, make a place, create a team that brings out the best in people in that way.'"

During her visit this past May, Duckworth met with Carroll and afterward with GM John Schneider. She talked to Seahawks scouts and coaches about grit. In the middle of the day, she addressed the team.

"They asked amazing questions," Duckworth said. "The questions were just the same as I would get at Yale. What about nature and nurture? If you create an organization that’s nicer, and you encourage people to stay, do you dilute the grit in your organization?"

The idea is reflected in several aspects of the Seahawks' organization. For example, their roster has more undrafted free agents (24) than any other in the NFL. They try to identify players who have shown the ability to rebound from adversity, oftentimes guys who have been passed over and are obsessed with proving themselves.

"It has a tremendous effect on how we overcome adverse situations because everybody’s been in there," Sherman said. "You have a bunch of, they call it grit, we call it dog. You’ve got a lot of guys with a lot of dog in them. They won’t take no for an answer. They won’t fail, they won’t lose. They won’t just quit. When you’ve got guys that won’t just quit and won’t just give up, and you’ve got 53 of them, you’ve got a problem. You’ve got an issue for a lot of teams. That’s not to say we’re going to win every game ... but we’re going to be dang hard to beat. At the end of the day, the score is not going to dictate our effort or our attitude. Guys have been in harder situations, have been in worse spots, and they understand that."

Added Carroll: "We’ve tried to find guys that have a sense about them that they can overcome whatever the odds are, and that they’re going to hang through anything. And that is demonstrated in the passion that they bring to their pursuits too. It’s exactly what we are looking for. We don’t care what their number is in the draft class. We just want to find guys that love playing, and they’ve got something, and they’re not going to be denied. That’s really where we’ve tried to build a whole crew around that."

The other aspect of perseverance is what Duckworth calls deliberate practice.

"When you look at experts, it’s not just the amount of practice they do, it’s the kind of practice that you do," she said. "It’s a practice that you try to do something that you can’t yet do. So challenges exceed current skill. [Carroll] is someone who models constant learning, constantly trying to get better at his job. It’s the opposite of complacency. That I could witness even on a single day."

Since 2010, the Seahawks are 5-2 when trailing by nine points or more in the postseason. The rest of the NFL is 6-41 during that span, according to ESPN Stats & Information.

After losing the Super Bowl in the most devastating way possible, they are two wins away from getting back to the game for the third straight year. Wilson threw the interception that sealed the Super Bowl loss. He bounced back and led the NFL in passer rating. Offensive coordinator Darrell Bevell made the call. He directed the league's second-most-efficient offense.

And then there's Carroll. He was fired from his first two NFL jobs before landing in Seattle. Duckworth was blown away by how he has built the Seahawks' program.

"You walk in there, and you’re like, ‘Oh, this is a culture. I get it,'" Duckworth said. "People have an identity there that they feel special, and they feel special in a particular way, and the language is all the same.

"I left [thinking], ‘This person is a world-class psychologist.’ He’s figured out without doing any random-assignment experiments what it means to encourage [grit] in people. When I see things in psychology or forecasting or economics that I think would help, I don’t send it to other coaches. I just send it to Pete."

The Seahawks have had a lead at some point in the fourth quarter of 16 of 17 games this season. The next few weeks will determine who the best team in the NFL is. And there's no doubt the Seahawks caught a break last week against the Minnesota Vikings. But Carroll's record of being competitive is impressive. And he believes in the science of grit.

For practical purposes, the idea relates to two major aspects of team-building: finding players and developing them. Duckworth has been schooled on the draft process. Identifying grit during short meetings with players at the Senior Bowl or the combine is difficult. But she has some ideas. For example, she suggested showing the players film of their worst plays and seeing how they reacted.

"See whether they focus on their mistakes and what they can learn from them," she said. "Or do they get defensive and not want to look at the film of their mistakes?"

In terms of player development, the Seahawks' track record speaks for itself. Seven of their players were selected to this year's Pro Bowl, but just one -- safety Earl Thomas -- was a first-round pick.

"We’re going to coach them to be the best player they can be until somebody else takes their spot," Carroll said. "And it doesn’t matter where you came from or what your draft number was or any of that kind of stuff. With discipline, you have to be disciplined to do that, because you tend to look to the guys that have all the acclaim and the hot-shot stuff. We do that too I think, but we also have disciplined ourselves to go deep into it and count on guys, and we’ve found so many guys with the competitive makeup and the character that drives you past whatever the numbers showed at the combine."

Carroll believes in the idea of being able to develop grit, and Duckworth said one key to doing that is to have a growth mindset.

That involves understanding failure is not a permanent condition and doing away with the notion that players have ceilings. Talent is important, but it's just the starting point.

"People with a growth mindset, people who truly believe that ability itself can be developed, not just that you can get good at something, but that your talent might change," Duckworth said.

"Could your talent for football change? Could your ability to learn football change? That’s really what growth mindset is, deep down believing about that malleability in people’s abilities and their talents."

Duckworth said she is now a Seahawks fan for as long as Carroll is the coach. She even knows what a "wild card" means. Her book comes out in May, and given Duckworth's résumé, it seems likely that her work will reach people in a variety of fields from finance to education to athletics. One of the chapters focuses on the culture of grit, and it features Carroll and the Seahawks.

"He gets so much about the way people think and their motivation and how they explain events themselves and how you support them," Duckworth said.

"Even though I also interviewed the general who runs West Point and the CEO of J.P. Morgan, I think there are more words in that book on Pete Carroll than anybody else."