Neuro-imaging is getting excitingly / frighteningly (depending on your viewpoint) subtle. A recent New York Times article reported on an imaging study which showed just why consumers prefer Coke to Pepsi! ('Why' is a complex question, and can invariably be answered at many different levels - this is one why). Latest marketing theory: if your medial prefrontal cortex fires when you see a particular product, it may be because the product clicks with your self-image. So when you say 'I'm a Chevy kind of guy', this is more true than you ever imagined!
(See about the BrightHouse Institute for Thought Sciences)