请柠檬解释一下这个现象，这篇文章说得也不是全对，但这个现象很值得深思：
http://www.worldnetdaily.com/news/article.asp?ARTICLE_ID=55266

The amazing fact is that guns, even guns in the hands of trained soldiers in the battlefield, don't kill people. While studying the effectiveness of American soldiers during World War II, U.S. Army Brig. Gen. S. L. A. Marshall discovered the incredible fact that less than 20 to 25 percent actually took part in battle using their weapons. After interviewing thousands of soldiers, even soldiers who had been in close combat with German or Japanese troops, Marshall and his team of researchers found that 75 to 80 percent of riflemen did not fire their weapons at the enemy, even to save their lives and the lives of their friends. Some of them prefer to die rather than kill the enemy. The reason for this was the strong inborn resistance of human beings to kill a fellow man. Further research revealed that the rate of soldiers firing at the enemy during the Civil War was very similar.

As a result of Marshall's findings, Army psychologists created new training methods, and they were applied in the soldier's training. The results were impressive. During the Korean War, the rate of soldiers firing their weapons in combat raised to 55 percent, and it reached 90 to 95 percent during the Vietnam War. What were these methods? Mostly brainwashing the soldiers to believe that what they were killing were not human beings, but pieces of inanimate matter. This was obtained through a process called manufactured contempt, which includes the dehumanizing of the enemy. Another factor that contributed to the high rate of killing in Vietnam was the extended administration of tranquilizing drugs to the soldiers. Does this ring any bells?