Why do i see and hear things that arent there?

We humans are ExcelLENT at recognizing patterns; sometimes TOO good, as we sometimes "recognize" a pattern that isn't there. Our brains see and hear fragments of images and sounds, and we sometimes identify those images and sounds inaccurately, because the parts that we DID observe fit (poorly) into a pattern that we had already seen.

So we "see" things that we EXPECT to see, and we hear what we expect to hear. And sometimes it's tough to take a second look and try to re-evaluate the old familiar pattern.