Access physics body shape in collisions

local object= display.newRect( 150, 120, 20, 150 ) topShape = { -10,-75, 10,-75, 10,-65, -10,-65 } middleShape = { -10,-64, 10,-64, 10,64, -10,64 } bottomShape = { -10,65, 10,65, 10,75, -10,75 } physics.addBody( object, "static", { density = 1, friction = 0, bounce = 0, shape=topShape }, { density = 1, friction = 0, bounce = 0, shape=middleShape }, { density = 1, friction = 0, bounce = 0, shape=bottomShape }

This is a vertical rectangle with 3 shapes

I have a character running left and right and when he hits this rectangle his direction changes (if he’s going left, he starts going right).
But I’d like that to only happen if I hit the middleShape.

Is there a way to do that or do I need 3 seperate objects to work the collisions?