Coke vs Pepsi, the science
Here's research near and dear to my heart. (I drink an inordinate amount of cola a day, and one of the books I read numerous times as a child was The Other Guy Blinked, aka Pepsico CEO Roger Enrico's story of the Cola wars.) Apparently Coke has such powerful branding that seeing the brand actually affects your nervous system's response:
The experimental design enabled the researchers to discover the specific brain regions activated when the subjects used only taste information versus when they also had brand identification. While the researchers found no influence of brand knowledge for Pepsi, they found a dramatic effect of the Coke label on behavioral preference. The brand knowledge of Coke both influenced their preference and activated brain areas including the "dorsolateral prefrontal cortex" and the hippocampus. Both of these areas are implicated in modifying behavior based on emotion and affect. In particular, wrote the researchers, their findings suggest "that the hippocampus may participate in recalling cultural information that biases preference judgments."