Barnes is on-loan at the Tykes from Leicester and has scored four goals in only 12 games.
Heckingbottom said: “Harvey's another one who has been getting better and better.
“He's another one that we speak to and are really pushing to improve, he knows exactly his awareness of himself and it's very good.
“So that makes it easier to work with when someone knows their strengths and weaknesses."
He added: “We've got a good competition in wide areas now.
“If anyone gets above themselves they can get dropped and someone else can come in so hopefully it keeps them all hungry."