The author of a study cited by Max Sawicky thinks this shows that protest demonstrations are “good for you” and people should do more of them. Well, that’s one way to read it.
Here’s another reading: Now we know why so many people put so much time and energy into demonstrations that are self-evidently worthless, or even counterproductive, in terms of actually achieving their announced political goals.
In the Jim Crow South, a “demonstration” actually demonstrated something: the ability of blacks to speak out together in the face of threats of legal harassment and deadly force, and the willingness of some whites to stand with them. A contemporary anti-war or right-to-life rally demonstrates only that its participants have nothing better to do, and prefer partying to actual political action.