The early 1950s also saw a number of movies depicting flying saucers and aliens, including "The Day the Earth Stood Still" (1951), "The War of the Worlds" (1953), "Earth vs. the Flying Saucers" (1956), and "Forbidden Planet" (1956). Despite this, public belief in ETH seems to have remained low during the early 1950s, even among those reporting UFOs. A poll published in "Popular Science" magazine in August 1951 showed, that of the respondents who self-reported as UFO witnesses, 52% believed that they had seen a man-made aircraft, while only 4% believed that they had seen an alien craft. However, an additional 28% were uncertain, with more than half of these stating they believed they were either man-made aircraft, or "visitors from afar." Thus the total number of UFO witnesses who considered the <abbr title="extraterrestrial hypothesis">ETH</abbr> viable, was approximately 20%. Within a few years, belief in ETH had increased due to the activities of people such as retired U.S. Marine Corps officer Maj. Donald E. Keyhoe, who campaigned to raise public awareness of the UFO phenomenon. By 1957, 25% of Americans responded that they either believed, or were willing to believe in existence of ETH, while 53% responded that they were not (though a majority of these respondents indicated they thought UFOs to be real, but of earthly origin). 22% said that they were uncertain.