Since the closing of Project Blue Book, the United States government has not had any official programs for studying UFOs. It is one of several private groups that continue to study the phenomenon. According to a United States Air Force guide published on the subject, the reliability of witnesses is one of the main considerations in all UFO sightings. One of the most common features of UFO reports is that witnesses often insist that the objects they saw were under intelligent control. People frequently come to this conclusion because, like Kenneth Arnold, who saw flying saucers above Mount Rainier, they believe they see objects flying in formation or toward another object or changing direction or speed dramatically.
People have a natural desire to explain and understand everything they see.
This is why visual sightings of UFOs are the least reliable. The unaided human eye can be tricked to the point of hallucination. A bright light, such as the planet Venus, often appears to move, though a clamped telescope or a sighting bar shows it to be fixed. A visual impression of distance is also unreliable because it is based on an assumed size. Reflections from windows or eyeglasses may provide superimposed views.