I've been thinking about Bladerunner (aka Do Androids Dream of Electric Sheep by Philip K. Dick) lately. In Bladerunner, there are androids ("replicants") which look fully human. There's one way to really tell if someone is human or android, and that's to subject them to a specific test. The test measures emotional responses to questions about animals--eating animals, wearing animals, animals in pain. Here's a link to a scene showing it from the movie with Harrison Ford (embedding disabled).
Why have I been thinking about this scene so much? Seeing the images of the animals in the Gulf Oil Spill (like these from the Boston Globe):