Gregory Berns and Sara Moore from the Center for Neuropolicy at Emory University have made a breakthrough in a phenomenon that has had us all scratching our heads: Why do certain songs get stuck in our heads? They have concluded that the strength of brain activity in teens could predict which songs would sell over 20,000 copies and which songs would not as calculated by Nielsen Standards. Labs show that 90% of the songs that received a weak neural response sold fewer than 20,000 copies. 
Berns and Moore created a focus group of 27 12-17 year olds, an age bracket that makes up 20% of music consumers. The group listened to 120 songs from unsigned artists while a MRI was tracking their neural responses. The listeners rated the songs on a scale of 1-5 and at times, popular opinion did not match the positive neural activity. However, the brain activity showed that some songs were more rewarding to hear and these songs correlated with higher sales numbers.
The original intent of this study was to determine how peer pressure influences teen choices and opinions but happened to be a catalyst for a growing field of research. According to the Wall Street Journal, psychologists and economists are now using MRI scans to determine the automatic judgments people make, below the surface of awareness, that help shape decisions, including purchasing and political choices. 
 Time Magazine