But the interesting thing for me is the flinch. As an example, our ability to interpret different colors works best when we're looking at a color range equivalent to that of leaves in a forest canopy. The visual complexity may be equivalent, but our relationship to our environment has changed. Living as hunter-gatherers, we needed to look for food and avoid predators. Because media is everywhere, the number of stimuli with significance to us seems to be much greater.
Physical evolution takes time, while our environment can change incredibly rapidly.
Though we can't change fast enough to evolve into a better relationship with our environment, our individual brains can habituate themselves to certain stimuli, often very quickly. Marketers and media people know this, so they up the ante. They crank the volume on the television commercial. They toss in more images. They add music.