Can people be influenced by subliminal messages?

Subliminal messages can work under very controlled conditions. “From my own research, you find an influence of subliminal stimuli…only ever under one particular condition,” says Friederike Schlaghecken, Associate Professor of Psychology at the University of Warwick. “You want a simple response to a simple stimulus and you want it now. If it gets more complex than that, you simply are not susceptible.”

A recent study has shown the first direct evidence that subliminal images can affect the brain. Researchers using brain imaging techniques have shown increased activity in the primary visual cortex, the area which processes visual information, when subjects were presented with images of everyday tools, such as irons, pliers or screwdrivers.

“This shows that you can pay attention to things even if you have never seen them,” says Bahador Bahrami, the lead researcher of the study at the Institute of Cognitive Neuroscience at University College London. But this subliminal effect was not seen when subjects had to concentrate on a difficult task, such as identifying different coloured letters.

“If you have a difficult task, you are going to apply all of your brain processing resources to it...but if they are idle then they are automatically dedicated to all the stuff that is happening, irrespective of whether they are relevant to your task or not,” says Bahrami. These results suggest that subliminal messages cannot be picked up if you are concentrating on a difficult task.

Other research has supported these findings. One study has shown that attention can be drawn by subliminal pornographic images of men and women, depending on the sexual orientation of the subject. Another study showed that people can subconsciously learn from subliminal messages; subjects who had been exposed to subliminal dot movement during a letter-naming task, were much better at picking out the same movement later.

Some may take these studies as proof that subliminal advertising can work, but they are disregarded by psychologists. “A pretty picture of the brain from a scanner tells you nothing about the human mind,” says Tunney. “There is no evidence here that subject’s behaviour can be influenced without them being aware of it.”

“You have to want to do it already,” says Schlaghecken. “Subliminal stimuli just speed you up a little bit and give you a tiny push in the direction you are going already.” There is no proof that subliminal messages can make you buy a product, or vote for a particular politician.

While the idea of subliminal advertising remains defunct, the influence of the subconscious brain remains a mystery. Science is unable to completely describe the extent to which this experience is involved in the way we live our lives. “We know that the brain has a subconscious side that is not clearly perceivable by us,” says Bahrami. “But a lot of our decisions, everyday life matters and our feelings are a lot more connected to those subconscious bits.”

There remains a lot more to understand about the subconscious brain and its influence over our everyday decisions and experience. At least we know that subliminal messages cannot make us suddenly brand Al Gore a ‘rat’, play a slot machine for longer or buy a product, unless we have made the decision already.

For more information

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