I disagree with the Dr. and security examples in comparison to this finding. The Dr. is not using the motor capacity and is simply looking for anomalies on an image. The security person may be a bit more subject to this as they would be handling items in luggage as well as viewing them. There is a difference between searching a familiar house for keys and using the eye to spot something that shouldn't be present.
http://www.youtube.com/watch?feature=player_embedded&v=5BgKTvNX2Vo
http://www.youtube.com/watch?v=M3jxjBdeJHc&feature=related