The Baggies host their West Midlands rivals at The Hawthorns on Sunday and Foster has highlighted the importance of keeping a clear head for such a potentially feisty encounter.
"I approach it the same as any other game really," Foster told the clubâ€™s official website.
"You can't really get carried away in the emotion of it. That's when you get some unexpected things from your game.
"You just have to take it as you would any other game and I think that's the same for all the players in our team.
"You just have to go into the game prepared and knowing your job, but also knowing you will have to handle it on the pitch as well because the atmosphere is going to be very tense and the fans will want to see heroics.
"They'll want to see you flinging yourself into challenges, which is fair enough.
"You have to respect that but keep a cool head at the same time."