Kelly Macdonald has a thick Scottish accent. That should be no surprise -- she is from Scotland, after all. I suppose her authenticity is partly what led Pixar to cast her as the lead in "Brave" (in contrast to Dreamworks relying on the fake [and annoying] Scottish accent put on by Mike Myers in "Shrek") -- that, and she's an excellent actress.
But hearing Macdonald's voice over the years, from "Trainspotting" to "Boardwalk Empire," has gotten me accustomed to it. Despite her brief appearance in the final Harry Potter movie, my kids have not had that luxury -- something that became apparent when Emily attempted to quote the tagline she's been hearing repeated in the previews for "Brave."
Emily's version: "If you had the chance to change your feet, would you?"