Why's that important? Well, because those people weren't seeing faces, they were just told that they might be by the scientists. So this suggests that instead of being first triggered by a simple external stimulus like an image of a human face, pareidolia automatically happens in the higher, more complex functions of the brain where the brain already thinks it's seeing a face and is trying to figure out who it is. And the phenomenon turns out to be much more common in people who believe in things they can't see.