Often steeped in controversy and skepticism, subliminal messages operate on the premise that the human mind can be manipulated through hidden messages within audio recordings or video advertisings. You don't need to see a subliminal message for long--1/5 of a second is enough--to become susceptible to its effects, and you only need to hear a quick line to have a seed planted in your mind. Scientists disagree regarding the effects of subliminal messages, primarily because some scientists are not even convinced that subliminal messages cause any behavioral changes.
Studies on subliminal messages show that the human eye and human mind are more likely to notice and retain subliminal messages with negative connotations. According to CBS News, a British study found that your brain is more likely to register words such as "agony," "murder" and "despair," than words with positive emotional associations such as "peace," "flower" and "cheerful." Such an effect may be considered negative because subliminal messages can be used to instill fear or anxiety in viewers or listeners.
Subliminal messages are common in the advertising field, where marketers hope to catch more of your hard-earned dollar by feeding messages to your subconscious mind. In February of 2007, for instance, casinos in Ontario, Canada, had to remove slot machines that briefly flashed images encouraging further gambling. The most famous instance of similar subliminal advertising was done by James Vicary in 1957, who added the phrases "eat popcorn" and "drink Coca Cola" to movie advertisements. When effective, such impact may be positive for the advertisers, though very negative for the consumers who end up spending money on items they do not need. As a result, many countries have banned the use of subliminal advertising.
Subliminal messages can be used positively through the use of self-help tapes and CDs. Many businesses have been built around creating self-help audio for losing weight, boosting self-esteem, improving memory, stopping smoking and more. Studies regarding the results of these tapes are inconclusive, though, noting that people do experience changes but recognizing that any changes may be merely a placebo effect.