The musical Sweeney Todd is about a barber who goes on a killing spree and disposes of his victims by baking them into meat pies. In an off-Broadway production, they serve you an actual meat pie before the show begins. Dr. Pamela Dalton, a researcher at the Monell Chemical Senses Center, helps us understand how food flavors and smells can affect our brains while we’re watching this kind of immersive theater.