Carragher has only returned to the England fold in the past two weeks.
"I think it's a mental thing with Capello," said the Reds vice-captain. "It's difficult for a manager to come in and make a massive improvement to players because we are talking about top-level footballers.
"But I remember he said when he first came here that some players were terrified of playing for England, especially at Wembley because of the reaction of the crowd at times.
"From what I have seen already, maybe he has improved the mental attitude of the players.
"His sheer presence also has a lot to do with it. He's a man of stature and, after what he has already achieved in the game, no one is going to question his methods."