What makes us reject the highly improbable?

Question

What makes us reject things that are technically possible, but are highly or extremely improbable?

For example, if a normal person was told that there were cameras hidden around their house they were unaware of they'd reject the idea, knowing that the odds are too great against it. However, if you told the same thing to someone with O.C.D., who already feared there being hidden cameras in their house, they might be more inclined to believe it. Why is that?

I'm searching for any kind of answer scientific(as in anatomy and such) or otherwise.

Answer 1

it's logic. "this hasn't happened before...why should it happen now? why would someone want to put cameras in my house?" it just seems simpler to believe the most logical idea. on the other hand a person with o.c.d has a mental disorder that makes them different