United were sixth in the table, seven points adrift of then leaders Chelsea, when they played at Newcastle at the start of last month.
They won 3-0 and it was the first of five straight league wins that have seen United go on to take a two point lead in the title race.
Ferdinand said: "Before kick-off at Newcastle, the manager showed us the league table - and it didn't make pretty reading.
"When we all saw it that day, with us at sixth, it hit home and we thought, 'Wow, we need to shake ourselves up'.
"Thankfully it turned out to be a good day for us with the win.
"I think the performance against Newcastle signalled a bit of a change in mentality from us and, hopefully, that's a taste of things to come for the rest of the season."