Nugent slotted the 70th-minute winner which gave npower Championship side Leicester a 2-1 win against Premier League Norwich at Carrow Road.
"Nugent is so confident. He plays with a smile on his face," Pearson sad.
"He is a very positive influence and his work-rate is exceptional. He is a very popular player in the team and today he showed the quality he has got."
He added: "We played with a lot of discipline and desire and didn't make a lot of mistakes."
Norwich manager Paul Lambert admitted he had no complaints with the result.
"We didn't do enough. Leicester deserved to go through and good luck to them. We never performed," he said.
Lambert, whose side lie eighth in the Premier League and have all but guaranteed survival this season, refused to blame the defeat on a weakened side, having made four changes from the team which beat Swansea away last weekend.
But he insisted the Premier League had been top of his priorities.
"It (the cup defeat) will be a blessing in disguise if we stay in the league," he said. "No-one would pat us on the back if we got to the quarter-finals of the cup and got relegated. I don't think the FA Cup is a discredited competition. But I wouldn't have wanted to do well in the FA Cup and get relegated at the end of the season. I picked a team I thought would win and that's my fault."