Subliminals are helpful in making modifications to the subconscious portion of a person's brain, which basically guides one's actions. Since this aspect of the mind is not equipped with the capacity for rational thinking, it will unerringly believe whatever it is told, for as long as it is done with enough repetitions or a sufficient amount of emotions.
You must wonder if it is possible for the two aspects of the mind – the conscious and the subconscious – to argue. The answer is a big "YES". Of course they disagree. And whenever this occurs, the subconscious mind would win the squabble all the time.
To get a better image of how the conscious and the subconscious aspects of the mind struggle against each other, try to picture this out: the conscious mind is usually left powerless when conflicting subconscious ideas – thoughts that could not be controlled by logical thinking – linger in a person's brain. In essence, the conscious mind is largely responsible for your "waking life", while the subconscious mind reigns in the "world of the dreaming".
How Does Ultrasonic Subliminals Work?
Ultrasonic subliminals make the most of the fact that the conscious side of your brain is intended to concentrate only on a few things, while the subconscious aspect makes a note of everything that is registered by any of your five senses.