"Not true; I wouldn't do that," Manning said about intentionally messing up the test. "I understand the seriousness of concussions. Our job was to be entertaining to the crowd. Got some laughs out of it, but it was really unfortunate."
The NFL has standardized sideline concussion examinations for all 32 teams. Dr. Richard Ellenbogen, co-chairman of the league's head, neck and spine committee, said in a conference call earlier this month that a decision to let Philadelphia Eagles linebacker Stewart Bradley back into the 2010 opener against the Green Bay Packers led to significant improvement in the detection and treatment of concussions during the rest of the season.
Manning said in the ESPN interview that the league required players to take new brain tests involving drawing and writing.
"Then, after a concussion, you take the same test, and if you do worse than you did on the first test, you can't play," he said. "So I just try to do badly on the first test."
As an aside in the ESPN.com article, Archie Manning slapped his forehead in disapproval.
The Associated Press contributed to this report.