Shearer has introduced stringent new regulations with increased fines for offenders and Joey Barton has been suspended until further notice following a breach of discipline.
Goalkeeper Harper is happy with the direction that Shearer is looking to take the club in, admitting there were problems that needed addressing.
"Players respond to discipline, it's needed," Harper told NUFC TV.
"At times in the past, it maybe wasn't what it should have been here.
"But he (Shearer) has tightened it up and players respond to it, and that can only be a good thing."
Shearer was appointed as boss at St James' Park last month and, despite failing to win any of his first five games in charge, Harper insists he has made a positive impact.
Still in touchThe Magpies have three matches left to secure their Premier League survival and Harper is still in confident mood.
"He has tightened things up and lifted the atmosphere around the place," said Harper.
"The fixture list hasn't been kind to us and we have been missing a few players, but he is definitely the right man to try to get us out of this situation.
"We were drifting along. We have lost three of the games and managed to get a couple of draws.
"But just remember what Alan Shearer does to this club - if anybody was going to get us to win these next two games and go into Villa full of confidence, then it would be the gaffer.
"We are still in touch. We have got two home games now and if we can get maximum points, we have got to fancy our chances."