Benitez took over from Steve McClaren at the start of the month, and he has only been in charge for two matches to date.
However, Lascelles feels that the Spanish manager has already proven how thorough he is through his methods on the training ground.
“He has had a positive influence already,” the former Nottingham Forest defender said. “Having someone else is a breath of fresh air — and especially someone who has been at Real Madrid.
“You can tell he has something extra in the way he speaks to us and coaches us. Everyone was pleased. He shows so much respect to us and his door is always open which is important.
“He has got to know everyone. We have all had a lot of conversations individually. He has a laugh and a joke when the time is right. If you are not doing your job he lets you know and that is what we need.
“Because he is such a big character and has been at such big clubs no one wants to put a foot wrong. It lifts training and makes it more intense.
“We know our roles now, the tiny details — if the ball is here , we should be there . Small things [but] really important. That can make the difference.”
Lascelles has had an important role to play since Benitez took charge, and he has started in both matches the ex-Real Madrid boss has taken charge of.
The centre back could be in line to keep his place for Newcastle’s match against Norwich City this weekend.
Despite Benitez’s impact, he is yet to win a match since taking over at St. James’ Park.
The Magpies lost to Leicester City in his first game at the helm, before drawing with Sunderland in their most recent outing.
Those results have left Newcastle sitting in 19th place in the Premier League table - three points adrift of safety.