Subliminal advertising 'affects brain'

Invisible subliminal images do attract the brain's attention on a subconscious level, researchers at University College London have claimed.

Using brain scans, researchers looked at whether an image you aren't aware of - but one that reaches the retina - has an impact on brain activity in the primary visual cortex, part of the occipital lobe.

Subjects wore red-blue filter glasses that projected faint pictures of everyday objects (such as pliers and an iron) to one eye and a strong flashing image known as 'continuous flash suppression' to the other. This recently developed technique effectively erases subjects' awareness of the faint images so that they were unable to localise the faint images on screen. At the same time, subjects performed either an easy task - picking out the letter T from a stream of letters, or a task that required more concentration in which subjects had to pick out the white N or blue Z from the same stream.

Researchers found that during the harder task, the subjects' brains blocked out the subliminal image and the scan did not detect any associated neural activity. Researchers said that finding that the brain does not pick up on subliminal stimuli if it is too busily occupied with other things, shows that some degree of attention is needed for even the subconscious to pick up on subliminal images.

Dr Bahador Bahrami, of the UCL Institute of Cognitive Neuroscience and the UCL Department of Psychology said: "What's interesting here is that your brain does log things that you aren't even aware of and can't ever become aware of. We show that there is a brain response in the primary visual cortex to subliminal images that attract our attention - without us having the impression of having seen anything. These findings point to the sort of impact that subliminal advertising may have on the brain. What our study doesn't address is whether this would then influence you to go out and buy a product. I believe that it's likely that subliminal advertising may affect our decisions - but that is just speculation at this point."

Dr Bahrami added: "This is exciting research for the scientific community because it challenges previous thinking - that what is subconscious is also automatic, effortless and unaffected by attention. This research shows that when your brain doesn't have the capacity to pay attention to an image, even images that act on our subconscious simply do not get registered."

Subliminal advertising is now banned in the UK, but is still legal in the USA.

The study is published in 'Current Biology'.

(KMcA)