Most people have heard of subliminal advertising - the idea that marketers hide a message in an advert that subconsciously ‘brainwashes’ people into buying a brand. But is there any evidence for this? The most famous example of subliminal advertising comes from an ‘experiment’ conducted at a New Jersey Cinema in 1957 by James Vicary. Over the course of several months, 45,000 visitors to a cinema were unwitting participants in one of consumer psychology’s best-known experiments. As they were watching Elvis Presley star in Jailhouse Rock, Vicary added in extra frames to the movie. These frames contained a few words: ‘Hungry? Eat Popcorn’ or ‘Drink Coca-Cola’. Each frame was only on screen for .03 of a second – just over a blink of an eye, and too fast for our brain to be consciously aware of, but Vicary argued that it was long enough for our subconscious to process.
The result? Sales of popcorn increased by a whooping 57.5% and sales of Coca-Cola increased by 18.1%. Clearly, that brief exposure changed movie goers’ behaviour. Unsurprisingly, this result had major implications. The CIA attempted to work out how they could use it for ‘research’ purposes, and subliminal advertising was swiftly banned in several countries - including the UK. There was just one catch – the experiment never happened. Vicary was a marketer, and this was just a gimmick used to promote a failing cinema.
But truth has never got in the way of a good story. This story was published in Vance Packard’s book, “The Hidden Persuaders’ and the experiment has become an urban myth. Yet the idea has excited psychologists for nearly 70 years. In that time, they devised over 25 different experiments, testing the concept on over 3,500 participants. But each time the results were the same – subliminal advertising had no effect. So, is subliminal advertising dead? Well, it seemed to be the case, until 2006.
In 2006 a team of social psychologists from University of Utrecht were able to recreate the effect for the first time6. They were trying to subconsciously influence participants to buy Lipton Iced Tea, and while they managed to achieve this, there are a couple of major caveats. Firstly, the effect was only shown in a highly controlled laboratory environment. Secondly, they were only able to influence participants who were already thirsty. Finally, flashing the brand logo made the brand name more ‘cognitively accessible’ in the participants’ mind. Consequently, while they were able to prime people to want to drink more Lipton Iced Tea, the same approach could not be used for Coca-Cola – as it would be hard to imagine making Coca-Cola more familiar than it already is.
So, are brands going to start looking for ways to get around the legal restrictions and start using subliminal advertising? Probably not. As we said, this effect was shown for the first time in a highly controlled laboratory environment. When one of the researchers attempted to recreate the experiment in a naturalistic setting, a cinema
(albeit for a BBC programme and not a controlled experiment), the effect vanished. It's worth noting that this was not just any cinema, the researchers were able to select participants who they knew were thirsty as they had given the audience members salty crisps beforehand.
Where does this leave us?
Well after nearly 70 years, it’s probably about time researchers stopped giving subminimal advertising the benefit of the doubt. While it has been a great device for novels and tv shows, there’s just not the evidence to support it from a behaviour change perspective. And that is even before we consider the legal, ethical and public relations issues associated with such a technique!
While subliminal advertising may not work, this does not mean that psychologists cannot influence shoppers while they shop. For example, studies have shown that playing stereotypical German music in the wine aisle increased sales of German wine, whereas playing stereotypical French music caused a spike in sales of French wine7. In both cases shoppers were unaware of the background music and yet it still influenced their behaviour. And what about aromas? When simple aromas such as pine or citrus were released in a store, shoppers spent about 20% more than when no scent was present. Interestingly when complex smells are released in store (for example an orange-basil-green-tea scent – yes really) it had no impact on sales8. But once again, shoppers had no idea that these aromas would influence them. Aroma influences our behaviour even if we are not aware of it – or to put it another way, we can be influenced subconsciously. (If you’re curious, why only the simple aromas influenced sales it is because simple aromas do not require much mental processing to trigger images associated with them. However, we are simply confused by a complex scent such as orange-basil-green-tea scent).
When one of the original researchers attempted to recreate the experiment in a naturalistic environment, a cinema, the effect vanished.
So while subliminal advertising may be dead, that does not mean there are not lots of ways that marketers and psychologists can influence shoppers and consumers without them being consciously aware of it.