Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - General Deactivate the alt-highlight function

Just so you understand (and maybe you already do), the alt-highlight function is to let you know what your characters can see, not what you the player can see from your third-person perspective. And it's based on their perception stat (not your real-life perception) - the lower a character's perception score the less effective holding down alt is at scanning the area.