"Attention is not some monolithic brain process. There are different types of attention..."

"... and they use different parts of the brain. The sudden loud noise that makes you jump activates the simplest type: the startle. A chain of five neurons from your ears to your spine takes that noise and converts it into a defensive response in a mere tenth of a second — elevating your heart rate, hunching your shoulders and making you cast around to see if whatever you heard is going to pounce and eat you. This simplest form of attention requires almost no brains at all and has been observed in every studied vertebrate."

Excerpt from "Why Listening Is So Much More Than Hearing."

That passage calls to mind the subject of "incitement" in the constitutional law of free speech. Here's Justice Brandeis in 1927:

Those who won our independence by revolution were not cowards. They did not fear political change. They did not exalt order at the cost of liberty. To courageous, self-reliant men, with confidence in the power of free and fearless reasoning applied through the processes of popular government, no danger flowing from speech can be deemed clear and present unless the incidence of the evil apprehended is so imminent that it may befall before there is opportunity for full discussion. If there be time to expose through discussion the falsehood and fallacies, to avert the evil by the processes of education, the remedy to be applied is more speech, not enforced silence. Only an emergency can justify repression. Such must be the rule if authority is to be reconciled with freedom. Such, in my opinion, is the command of the Constitution. It is therefore always open to Americans to challenge a law abridging free speech and assembly by showing that there was no emergency justifying it.

There's a distinction between what is heard and what is listened to.

***

I Googled "incitement and free speech" to get a nice clear link to insert in the sentence between the 2 links above. Virtually everything that came up on the first page of results had to do with the "Innocence of Muslims" video/Muhammad cartoons.