"It doesn't take a rocket scientist to figure out if (you have) a concussion, you're probably damaging your brain a little bit. Just like if you sprain your wrist a bunch, you're going to have some wrist problems down the road. Yeah, I'd still play through it. It's part of it. It's part of the game," Smith said. "I think if you're noticeably messed up, yeah, they'll take you out. But if you've just got some blurry vision, I'd say that's the player's call. And most guys -- 99 percent of guys in the NFL -- are going to play through it."

Smith said he sustained one concussion in high school ("You don't know who you are," is how he described it) and another in college ("Walking around the whole time, but I don't remember anything until six hours later").

The NFL likes to say that views about concussions have shifted from simply accepting they're part of the sport to doing what's possible to lessen impacts. Commissioner Roger Goodell talks about "changing the culture," so players don't try to "walk it off" after taking hits to the head.

Yet the AP's conversations with players showed there is room for more adjustments, which did not surprise Dr. Richard Ellenbogen, co-chairman of the NFL's head, neck and spine committee.

"The culture change takes awhile," Ellenbogen said in a telephone interview. "Why would these guys want to go out? They love playing the game. They don't want to leave their team. They want to win. I understand all that. And that's why we have to be on our toes with coming up with exams that are hard to beat, so to speak."

New Orleans Saints offensive lineman Zach Strief put it this way: "We all grew up with, 'Hey, get back in there. You (only) got your bell rung.' And while it's changing now, I think it's going to take time for the mindset to change."

A few players said they'd be particularly inclined to hide a concussion if it happened in a playoff game or the Super Bowl. Some said their decision would depend on the severity of a head injury -- but they'd hide it if they could.

Clearly, there is a stigma associated with leaving the field, no matter the reason. Indeed, one player who said he'd exit a game if he thought he might have a concussion didn't want to be quoted on the subject.

Other findings from the interviews:

• Asked whether the NFL should have independent neurologists at games to examine players and determine if they should be held out because of concussions, 31 players said "yes," and 10 said "no." Three didn't answer.

"They've got guys looking at your uniform to make sure you're wearing the right kind of socks," St. Louis Rams safety Quintin Mikell said. "Why not have somebody there to protect your head? I think we definitely should have that."

He said he's tried to clear his head and stay on the field "many times."

"I'll probably pay for it later in my life," Mikell said, "but at the same time, I'll probably pay for the alcohol that I drank or driving fast cars. It's one of those things that it just comes with the territory."

• Specifically regarding concussions, 28 of the 44 players think playing in the NFL is safer now than in 2009, while 13 think it's the same, and two think it's more dangerous. One wasn't sure. Those who think safety has improved gave credit to the rise in awareness; more fines for illegal hits; this season's changes to kickoff rules that have cut down on the number of returns; and the new labor contract's reduction in the amount of contact allowed in practice.

"When I first came into the league, it was like, 'Whatever goes.' It was more of that old-school, just 'beat-him-up' football. Not wanting to hurt anybody, but show how tough you were. Back in the day, it was like if you come out (of a game) with (a) slight concussion, then you weren't giving it all for your team," Buffalo Bills linebacker Andra Davis said. "But now, they're taking that option away from you."

Davis, a 10th-year veteran who turned 33 on Friday and said he's had a couple of concussions, is one of those whose view on seeking help for such injuries has changed.

"The younger me would definitely hide it," Davis said. "But the older me now -- with wife and kids and looking more at life after football -- I would say something about it."

• Asked whether more can be done to protect players from head injuries, 18 players said "yes," and 24 said "no." Two did not respond.

Not surprisingly, there were divisions according to position, and players on opposite sides of the ball generally drifted toward opposing views: Those on offense seemed more likely than those on defense to say more can -- and should -- be done to improve safety. Linemen, meanwhile, often complained that there is no way to improve their plight, with the helmet-to-helmet banging that takes place at the snap on play after play. One player described those collisions as "micro-episodes that build up over time."

Nearly three-quarters of the players who told the AP they think safety can improve -- 13 of 18 -- suggested equipment can be improved, too. Helmet technology, mouth guards and chin straps all were mentioned.

Two players suggested more education about concussions is needed.

Dr. Robert Cantu, a senior adviser to Ellenbogen's NFL committee who said he is consulted regularly by the league, insisted that while there has been progress, there is still work to be done.

"Has there been a culture change overall? I think the answer is, unquestionably, 'yes.' Could there be more done? Yes. Do all the players get it? No. Do they want to get it? No," said Cantu, a clinical professor of neurosurgery and co-director of the Center for the Study of Traumatic Encephalopathy at Boston University School of Medicine.

CTE is a degenerative disease increasingly found in football players and other athletes who have absorbed repeated blows to the head. It has been linked to memory loss, disorientation, poor decision-making, and depression that can lead to drug use and, as in the case of former Chicago Bears defensive back Dave Duerson, even suicide.

The league distributed informational posters in 2010 to warn about the dangers of head injuries, but Cantu said: "Just because the posters are in every locker room, it's not mandatory reading. Or people can say they read it but not really have read it."

"More stress needs to be placed -- and I believe this is the players association's responsibility as much as it is the NFL's -- on the dangers of playing symptomatic with a concussion and more knowledge needs to be imparted on chronic traumatic encephalopathy, which obviously does exist in the NFL. ... All of those sub-concussive blows count, and you need to minimize the amount of brain trauma that you take," Cantu said.

Union spokesman George Atallah declined a request for comment about concussions.

Little-discussed until reporting by The New York Times led to an October 2009 congressional hearing on concussions in the NFL, head injuries are now part of the daily conversation about professional football. On Saturday alone, two starting quarterbacks, Cleveland's Colt McCoy and Arizona's Kevin Kolb, sat out because of head injuries, while a third, Minnesota's Christian Ponder, left his team's game with what his coach called "concussion-like symptoms."

According to data from STATS LLC, from 2000-09, an average of 3.1 NFL players -- and never more than nine in an entire season -- went on injured reserve because of a concussion or head injury. That number rose to 18 last season, and stood at 17 through Week 15 this season.

Similarly, STATS LLC said, over that same 10-year span at the start of the century, an average of 26 NFL players each season were listed on the weekly injury report and missed games because of a concussion or head injury. That number rose to 89 in 2010, and stood at 75 this season through Saturday's games.

At least eight lawsuits have been filed against the NFL in recent months -- including three within the last week -- by dozens of former players who say they have medical problems related to brain injuries from their time in professional football. The NFL's stance, in part, is that players knew there were risks of injury, and there was no misconduct or liability on the league's part.

"It's a physical sport. Guys are going to get hit in the head. When we're young, when we start playing this sport, we know what we're getting into," Philadelphia Eagles tight end Brent Celek said. "It's not like, 'Oh, I'm going to play this because my head's going to be fine when I'm done playing.' It's a risk you take playing this game, but I think the league is doing everything in their power to make it as safe as possible."

The NFL certainly has found itself adjusting on the fly.