Royals made it 14 points from their last seven Premier League games with a hard-fought win over Martin O'Neill's men at Madejski Stadium.
Two goals from Jimmy Kebe either side of a Craig Gardner equaliser secured all three points for Brian McDermott's men who are now two points above the relegation zone.
And centre-back Pearce believes the manner of the weekend's victory shows just how much Royals have improved since a 3-0 loss at Sunderland in a re-arranged fixture in December.
Pearce declared: "The gaffer said to us before the game that we owed Sunderland one.
"We really wanted to make amends for that night because that really wasn't us. We were dominated by Sunderland, we sort of got beaten up.
"But that's what we did to Sunderland on Saturday so we're very pleased about that."
Reading occupied bottom spot in the table at Christmas and were hot favourites with the bookmakers to be relegated.
But they have turned their fortunes around in recent weeks and are now unbeaten in six games in all competitions.
Pearce stressed: "We always believed we could turn the corner. We kept our belief because the manager has installed that in us.
"He told us the prize is still there for us if we want it, and we believe we can do it.
"We're starting to prove that now by going on a run, as we have done over the past three years.
"If you look at our record, any team who comes to the Madejski is going to find it hard.
"We just keep going to the bitter end. I thought we dominated the first half against Sunderland and the game in general.
"Pavel Pogrebnyak was unlucky and gave away a penalty, but these things happen. We battled on through that, stuck together and came through in the end thanks to a great header from Jimmy Kebe."
Reading had to dig deep to overcome a tough Sunderland side and they will need to show similar battling qualities when they travel to Stoke City's Britannia Stadium this Saturday (3pm ko).
However, Pearce is confident they can cope with the Potters' physical approach.
"It will be a good game I think," he argued. "But it won't be for the faint hearted that's for sure.
"We will go there high on confidence and in high spirits. Stoke is a tough place to go to but in the form we're in at the moment we believe we can take on anyone."
Before that, Pearce is relishing the opportunity to win his second international cap for the Republic of Ireland when they take on Poland in a friendly at the Aviva Stadium in Dublin tonight (Wednesday, 7.45pm ko).
The 24-year-old received a call-up from boss Giovanni Trapattoni last week and said: "It's a nice distraction really. It's international football and I want to go there, hopefully get on the pitch and show Mr Trapattoni what I'm about and what I can do."