An example system includes an analyzer to determine a first distance between (1) a first peak in a first frequency band of first neuro-response data gathered from a subject while exposed to media and (2) a second peak in the first frequency band; determine a second distance between (1) a third peak in the first frequency band and either (2) the second peak in the first frequency band or (3) a fourth peak in the first frequency band and determine a first difference between the first distance and the second distance. The example system includes a selector to determine a modification for the media based on the first difference and a modifier to implement the modification for presentation of the media.