According to driveintheater.com(1), Project Silver Screen was started in 1948 by the National Security Group (NSG) to look into a possible connection between debris from the 1947 Roswell UFO crash and drive-in movie theaters. The NSG discovered that UFOs had been, from at least the time of the Flintstones, reflecting signals off of the large movie screens at drive-in theaters. It was noted that these bi-directional signals from the UFOs could measure the brain activity and emotional response of each person attending the drive-in movie.
Did aliens design drive-in movie theaters so they could study us? Decide for yourself and have fun reading more about Project Silver Screen here(2).