In an experiment, volunteers walked individually through a dark, abandoned theater. Half of the volunteers had been told that the theater was haunted and the other half that it was under renovation. The first half reported significantly more unusual experiences than the second did. The researchers concluded that reports of encounters with ghosts and other supernatural entities generally result from prior expectations of such experiences.
If true, none of the volunteers in the second half believing that the unusual experiences they reported were supernatural would most seriously weaken the researchers' reasoning.