The ideas of subliminals are ancient, dating back to 5th century B.C. where Greek philosophers tried to use persuasive language to influence people to behave certain ways. The modern day idea of subliminals, however, dates back to 1943. Subliminal messages were hidden into films, radio, and television programs. It was unknown if these messages would influence people at the time. In 1957, market researcher James Vicary hid the words "eat popcorn" and "drink coca-cola" into a movie, and the words appeared for a single frame. The subliminal ads allegedly created a 18.1% increase in coke sales and a 55.78% increase in popcorn sales, but these results were proven to be a hoax. Throughout the 1960s-80s, studies were not in fsvor of subliminals doing any behaviorally change. It wasnt until the 90s that subliminals were proven to make subtle changes. In the early 2000s, they were shown to very narrowly change our perception. In a 2007 study, subliminal messages were shown to students before a exam, and the ones who saw the messages related to intelligence did better on a midterm one to four days after. In 2010-2015, studies shown that the human brain responds to subliminal messages in measurable ways. Activity changes in the amygdala, which processes emotions, the insula, which plays a role in conscious perception, the hippocampus, which processes memories and learning ability, and the visual cortex, which processes visual information. The modern day meaning of subliminals, the one you see on youtube, on tapes and cds, etc, are usually more based off of the concept of the law of attraction rather than the scientific proof. I belive the problem with subliminal advertisements failing is because the audience were in a conscious state, and most likely not in a relaxed or calm state. When you are watching a ad or show, you are most likely in a alert mode. The subconscious is most active during sleep, before or after sleep, or doing something creative or relaxing as long as it does not take up too much concentration. Because the idea of subliminals is that the subconscious mind will react to messages the conscious cant register, it'd make more sense for subliminals to work when you're subconscious is more active.