In a different study (Strack & Mussweiler; pdf) asked one set of participants "Did Gandhi live to the age of 140?" The participants presumably all responded, "No." The second question was to estimate how long Gandhi lived. The average estimate was 67. The second group of participants was first asked "Did Gandhi live past the age of 9." Again, presumably everybody replied correctly. On the second question, they estimated on average that Gandhi lived to 50. There are many other examples. This is why experts will tell you that polls are next to meaningless unless you know the exact wording of the question. It's not subliminal mind control like in the movies, but manipulating people's decisions (or, at least their answers to surveys) is fairly easy.