The Clarets looked to be on their way to a vital victory against one of their relegation rivals when they took a two-goal lead at Turf Moor.
But Chris Brunt headed in a corner just before half-time before Brown Ideye profited from another corner midway through the second half.
Burnley have conceded 14 headed goals this season, more than any other team in the Premier League.
And Pulis said his side were looking to punish them from corners and free-kicks.
Ahead of Wednesday’s game with Swansea City, the Baggies manager said: “We look at set-plays very closely and we thought they were very vulnerable at the back (post).
???The first goal we got in there. The second goal was a little bit of a block that we work on.”
Burnley boss Sean Dyche felt Ideye’s goal should have been disallowed for a foul by Gareth McAuley on David Jones and refused to see it as a particular weakness.
“I’m no more concerned about that than can we progress through our passing, can we affect the games by scoring more,” said Dyche.
“They’re all part of the game. You have to be concerned with every element of the game. You can’t restrict it to one element.
“We have to defend better at set-pieces, like every other team has to defend better, so it’s not just us.
“You’ve got to remember the quality of delivery coming in is better than last season. Certainly with the consistency of delivery – and the will and desire to deal with that is there, but it has to be with the format.
“The structure’s good and we just didn’t deal with two set-pieces, although one’s a foul.
“We’re conceding more than we’d like but there is that fine balance. We’re close to it, we’re improving, we’re 17th in the Premier League, so overall we’re in good shape.”