The idea that we can be influenced by ads we don’t consciously detect is one of most intriguing in consumer psychology and has attracted a lot of attention over the years. Since the 1950s, people have feared that words or images briefly flashed on a screen or concealed in an advertisement have the power to make us buy certain products or even vote for a certain political candidate. Are these fears founded, or is this more myth than reality? The answer, believe it or not, is yes and no: While there are widely held false beliefs about subliminal advertising, it can influence us. In this post, I’m going to explain this seeming contradiction, starting with a discussion of what subliminal advertising is and the origin of popular beliefs surrounding it, and then finishing with a discussion of when it actually does influence us. After reading this, you might start to look at the ice cubes in that liquor ad a little differently.
Subliminal advertising is that making use of words or images (referred to as stimuli) we don’t consciously detect. Those stimuli can be undetectable because they’re hidden inside of some other image (e.g., concealing the word "sex" in some ice cubes in a liquor ad), or because they’re presented on a screen so briefly we’re not aware we’re seeing them. How briefly does something have to be presented to be undetectable? The oft-agreed duration is .003 seconds (that’s three one-thousandths of a second). Most people will not be consciously aware they’ve seen a stimulus that was presented for .003 seconds. Regardless though of whether a stimulus is considered subliminal because it’s concealed in something else or because it’s presented very briefly, the distinguishing feature is that we’re not aware we’re looking at it. When subliminal stimuli exert an influence on us it’s said to be an unconscious influence, meaning it’s an influence we’re not consciously aware of.
Distaste for subliminal advertising began in 1957, after James Vicary and Frances Thayer published a study in which they claimed that subliminally presenting the words “Eat popcorn” and “Drink Coca-Cola” in a film increased popcorn sales by 58% and Coca-Cola sales by 18%. Those are obviously huge sales increases considering all Vicary and Thayer claimed to have done was present a few words on a screen. The following year, a man named Vance Packard published a book called The Hidden Persuaders, in which he discussed how advertisers could control consumers by appealing to their unconscious desires. Indeed, Packard’s claims of advertisers’ ability to influence consumers were analogous to a puppet master pulling a puppet’s strings. After learning about Vicary and Thayer’s study and reading Packard’s book, people feared advertisers could use subliminal advertising to force them to buy products and politicians could even use subliminal advertising to force them to vote a certain way. People also feared skepticism and suspicion would be useless against this form of influence because after all, we can’t be suspicious of something we’re not even aware we’ve seen. The fear of subliminal advertising was largely unfounded though, as Packard heavily exaggerated advertisers’ power over consumers, and Vicary and Thayer fabricated their data. That’s right, they just made it all up for no other reason than to promote Vicary’s own marketing company! Additionally, legitimate research (i.e., research that did not make use of fabricated data) conducted after the publication of Vicary and Thayer’s study found very little evidence that subliminal advertising exerted any influence on people. Despite this though, the myth that subliminal advertising has a powerful influence endures: Recent survey data showed over ¾ of respondents knew of subliminal advertising and almost half felt susceptible to it.
If the fear of subliminal advertising is largely unfounded, this begs the question: Can we ever be influenced outside awareness? The answer, actually, is yes. Research showed that when words relating to thirst were subliminally presented to thirsty people they later drank more. This, despite the fact that these people did not report being thirstier! This implies these people were not only unaware of seeing the thirst related words, but were also unaware of the words’ influence on their behavior. Other research showed stimuli people were aware of could exert an influence on their behavior they were not aware of. For example, research showed that liquor store patrons bought more German wine when German music was playing in the store and more Italian wine when Italian music was playing in the store. When asked what led them to choose the wine they chose very few patrons mentioned the music, implying that despite the fact they could hear the music most of them were unaware it was influencing their behavior. Other research showed that people who watched someone eating ice cream before being given the chance to eat ice cream themselves would unknowingly eat the same amount of ice cream as that other person (the only time this didn’t happen was when that other person was obese, but that’s a story for another post).
So clearly then, our consumption can be influenced without our awareness, be it due to exposure to stimuli we don’t detect or stimuli we do detect but which influence us outside awareness. At this point, I’d like to address a question that may have occurred to the reader: What’s the difference between the previously mentioned older research that showed no real evidence people could be influenced by subliminal advertising and more recent research that showed we can be influenced outside awareness? There are two differences, the first of which is that psychologists are now aware that to be effective subliminal stimuli must appeal to current needs and goals. For example, subliminally presenting thirst related words led people to drink more, when they were already thirsty. Second, psychologists are now aware that when it comes to stimuli we’re aware of but which influence us outside awareness we must not be aware the stimuli are exerting an influence on us. For example, if the liquor store patrons hearing the Italian music were told beforehand that the music would lead them to buy Italian wine many of them probably would have chosen wine of a different origin (if any). Additionally, if the people who imitated another person when eating ice cream were told beforehand that they’d copy that person’s eating behavior they probably wouldn’t have done so.
While a surprising number of people today still subscribe to the idea that subliminal advertising can make us do things against our will, that’s largely just a myth. Research has shown that subliminal ads and other stimuli designed to influence us outside awareness can do so, but not very powerfully. I mean, there’s a big difference between getting thirsty people to drink a beverage offered to them and making some presumably well-hydrated moviegoers purchase Coke. That said, subliminal stimuli and consciously detectable stimuli could influence our behavior without our knowledge when they’re used right. For instance, one purpose of playing upbeat music in restaurants is to make us eat faster and increase the restaurant’s turnover rate (and by extension its revenues). Most of us have no idea the music is influencing our eating, and the restaurant staff who are aware would never tell us. There are a few take away messages from all this: First, you needn’t be concerned that advertisements concealed in movies and TV programs are making you buy things, because at most they could only get you to buy something you’d be inclined to buy anyway, if they could even exert that much influence. Second, attending to your surroundings might reduce the influence of detectable yet unobtrusive stimuli that could otherwise exert an unidentified influence on your behavior.