Subliminal messages can affect our brains, researchers find
Posted May 16, 2005
Special to World Sciences
Courtesy Proceedings of the National Academy of Sciences
In the 1950s, a frightening rumor originated that has never died down. Our decisions can be influenced without our knowledge or control through “subliminal” messages—words or pictures presented in such a way that we don’t consciously notice them. For instance, an advertiser might flash words such as “drink Coke” on a movie screen too briefly for conscious notice, with the result that cola sales go up at the popcorn counter.
Now, researchers say it is becoming clearer that the rumors might have a kernel of truth: so-called subliminal messages can in fact affect our brains. Moreover, these hidden messages activate the same brain areas as do overt messages of the same nature.
Some of the first studies purporting to demonstrate the reality of subliminal effects were later discredited. One of these studies, indeed, involved “drink Coke” messages at a movie
theater. Its author, James Vicary, later retracted the findings.
More recently, when Democrats in the United States accused Republicans of using subliminal advertising in 2000, the Republicans bristled. And advertising professionals protested that any such accusations were silly because there was no evidence that subliminal advertising works.
But more recent studies have supported the existence of at least some subliminal effects.
In a paper to be published in this week’s early online edition of the journal Proceedings of the National Academy of
Sciences, researchers report that people can unconsciously process the meaning of subliminal words.
The researchers found that briefly flashed messages of fear-related words tended to trigger activity in a brain region associated with fear.
The scientists measured brain activity during presentation of subliminal words by studying three patients with epilepsy who had electrodes placed in their brains as part of a presurgical evaluation.
On a computer screen, the patients viewed words flashed too quickly to be seen consciously, as well as visible words shown long enough to be detected.
Half of the words were threatening in nature, such as “danger” or “kill.” The other half were emotionally neutral, for instance, “cousin” or “see”. During word presentation, the researchers recorded electrical activity in the
amygdala, a brain structure that responds to fearful or threatening stimuli.
The researchers observed that the subliminal, threatening words were detected by the brain and elicited more electrical activity in the amygdala than neutral words. The quickly-flashed words were shown for about one thirtieth of a second—the same as the reported length of the flashed images in the discredited “drink Coke” study.
Differences in electrical activity evoked by threatening versus neutral words were similar, whether the words were consciously seen or subliminal, the researchers wrote. But consciously seen words were processed more quickly and elicited a stronger, more sustained effect than subliminal words.
These findings indicate that the emotional meaning of words can be accessed subliminally, occurring in the same brain region as conscious processing, wrote the researchers, Lionel Naccache and colleagues at the
Hôpital de la Salpêtrière, Paris.
Although the study is one of the first to be published in a prestigious research journal and to demonstrate that subliminal messages have an effect, it is not the only recent study to have backed up the notion. Several of the previous studies, though, have still not met the strictest scientific standards, Naccache and colleagues argue.
In one recent report, Princeton University’s Joel Cooper found that television viewers watching a program of The Simpsons became thirstier when subliminal messages related to thirst were embedded in the program.
“So, was Vicary correct
after all?” asked Cooper in his paper, published in the November, 2002 issue of the Journal of Applied Social
Psychology. “Our findings, along with a growing body of research in social cognition, suggest that there might be some truth to the suggestion that our motivational states are affected—and might even be caused—by pre-consciously perceived stimuli.”