It worked again. But this time I wanted to give the test a socio-economic context, so I went to not only two Wal-Mart stores but also to two upscale department stores (can't find that many here in Aheadofrepoman, Delaware). After briefly lingering inside each store, I then walked out its main door, making sure that several shoppers were about to enter. Then I quickly looked up into the sky shouting, "Look! Dead birds, dead birds!" It didn't matter what the socio-economic status of the shoppers, all of them near me kept looking up to see the dead birds.