When I was a small child, I thought the idea of subliminal messaging was way cool. Learn languages in your sleep! Control people’s minds by inserting inaudible dialogue into the background! Wicked!
To the best of my knowledge, that type of subliminal messaging — a hidden, language-based message — doesn’t exist (but if you have evidence of one, please comment!). Influencing another’s actions turns out to be pretty easy. There are many well-documented ways to manipulate others. I will focus here on getting the answers you want. Basically, response management comes down to how you phrase the question.
In a classic study by Tversky and Kahneman, participants were given two options for combating a plague that was projected to kill 600 people. Plan A was sure to save 200 people. Plan B had a 1/3 probability of saving 600 and a 2/3 probability of saving nobody. 78% of participants took the safe option: A. Rephrasing the question in terms of deaths (400 guaranteed under Plan A; 1/3 probably of 0 and 2/3 probability of 600 under Plan B) reversed the result: 78% of participants chose plan B. This is because humans are risk-prone when dealing with losses (“let’s hope for the best”) but risk-averse when dealing with gains (“let’s keep what we have”).
In another study by Tversky and colleagues, they found that if you offer a shopper a “one time only” sale on a piece of merchandice (e.g., a Sony CD player), most (66%) will buy it, happy to avoid further shopping. If you offer them two different products (one by Sony, one by Aiwa), both on sale, nearly half (46%) will continue shopping rather than buy either. The addition of choices makes people less likely to choose.
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.