The problem here is that this expedition's purpose was to find the Ark, and that they were trying to do so in an environment resembling a 3D rorschach test. And guess what they found...
If one looks hard enough for anything, they will find it regardless of whether it is really there.
Hmmm. By that reasoning, I guess next time you lose your keys, you better not go looking for them. After all, you starting your car up might be a figment of your active imagination. ;-)