Do UFOs exist? If they do not exist, why do people report them? Can we believe the reports; indeed can we believe anything? Is human perception reliable, or is it influenced by what we believe? Could the UFO myth determine what we see and report? If UFO reports are distorted by the UFO myth, what is the initial stimulus? In short, what have people really seen? Campbell explains the UFO myth, including its origin and development and how it influences everyone, including those who report seeing UFOs. He also explains how the human perceptual and memory systems can distort reporting and he lists most of the 'sources of deception' which can cause UFO reports. The author fearlessly tackles the most sensational and difficult reports and shows how they have simple and mundane explanations. Reports are explained in an objective and critical manner and it is shown how both believers and debunkers have missed the 'obvious natural explanation'. This handbook is for all serious investigators of UFO reports; it also offers the final solution to the UFO mystery.