1. A system comprising: an analyzer to analyze brain wave data gathered from a viewer exposed to a media instance to determine a first energy of a first frequency band at a first time, a second energy of a second frequency band at the first time, a third energy of the first frequency band at a second time and a fourth energy of the second frequency band at the second time; a calculator to calculate a first difference between the first energy and the second energy and to calculate a second difference between the third energy and the fourth energy; a processor to: generate a first output signal based on the first difference, the first output signal representative of a first emotional state of the viewer, generate a second output signal based on the second difference, the second output signal representative of a second emotional state of the viewer, and generate a third output signal indicative of a success or a failure of the media instance, wherein a positive change between the first emotional state and the second emotional state are indicative of a successful media instance.
2. The system of claim 1 further comprising a display to present the media instance and one or more of the brain wave data, the first energy, the second energy, the third energy, the fourth energy, the first difference, the second difference, the first output signal, the second output signal or the third output signal via a rendering.