Here's where I'll briefly tell you what are subliminal messages and how do they work so that you'll have a clearer understanding of what's going on here...
Subliminal messages are all the messages presented to us without conscious awareness that have an effect on our mood, thoughts, decisions or behavior.
The most known forms of presenting subliminal messages are through audio (audio tapes or CDs) and through video.
Scientific tests done to date have shown that none of the commercial audio subliminal messages have any effect beyond placebo. Audio subliminal tapes and CDs are supposed to contain messages embedded underneath the main track and aren't audible.
Unfortunately such messages because of the physiology of the ear and physics of sound can't and don't reach it's intended target... The brain. They get lost because stronger signals simply overflow them.
There have been some successful trials done with the so called "silent subliminals", where the frequency of the messages is boosted up to about 16-18 kHz. These messages are barely audible and can be presented very loudly, thus allowing for them to be transmitted to the brain.
Video subliminal messages, however, have proven to produce incredible results. In the last decade there were many different experiments done and effects on mood, behavior, decisions and thoughts has been have been incredible.
Video subliminal messages are single words, short sentences or images flashed on the screen for a very short amount of time, typically from 5 to 20 milliseconds. They work on the unconscious but don't get noticed consciously.
Subliminal messages prime behavior, which means that after stimulation one has a tendency to behave in accordance with the content of the messages. Because there is no interference from the conscious mind, the behaviors are viewed as "inner urges" and such person is much more prone to act out the suggested behavior.