By Mark Leary, Ph.D., Duke University
Can people be affected by messages that they can’t even see or hear? Can people’s behavior be affected by subliminal visual messages?
Buying Cola and Popcorn at the Movies
In the 1950s, a marketing researcher named James Vicary announced that he was able to increase Coca-Cola and popcorn sales in a movie theater by flashing subliminal visual messages up on the screen telling the people in the audience to drink Coca-Cola and eat popcorn. Vicary claimed that he was able to increase popcorn sales by 58 percent and Coke sales by 18 percent.
Well, Vicary’s experiment attracted a good deal of attention, not only from researchers in psychology and marketing, but also from the general public. Understandably, watchdog groups worried that advertisers could start using subliminal messages to manipulate us to buy their products. Or maybe even worse, governments and devious cults could use subliminal messages to brainwash people. And we wouldn’t even know it.
There was only one problem. Vicary admitted a few years later that he made up the results entirely, and later investigations suggested that he might not have even conducted the study at all. Scientists who tried to replicate his findings by presenting subliminal messages couldn’t get people to do things.
This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, Wondrium.
Subliminal Visual Messages
What is a subliminal stimulus? A subliminal stimulus is a stimulus that we cannot consciously perceive.
So, for example, if I flash a word or a picture on a computer screen for only 40 milliseconds—40 thousandths of a second—you won’t see it, at least not consciously. But the question is whether the information in that word or that picture gets into your brain anyway, without you consciously detecting it at all.
And if it does, can that subliminal visual or word affect what you think, what you feel, or what you do? If I flash the message “eat popcorn” to you subliminally—below the threshold of your conscious awareness—will the message increase the likelihood that you’ll want popcorn?
Learn more about why self-control is so hard.
Soup or Popcorn?
There’s no question that we are affected by things that we aren’t consciously aware of. You constantly think and do things without having any idea whatsoever what the stimuli were that led you to think or do them. And you are certainly not aware of the processes inside your brain that led to your thoughts and behavior.
Imagine that you haven’t given any thought at all about what you’ll have for lunch. Then suddenly, you think “I think I’d like soup for lunch today.” What caused you to decide? Of all of the things you could have eaten, why did you decide on soup?
Presumably, something made you decide on soup rather than something else, but usually you aren’t aware of what it was. So, there’s no question whatsoever that we are constantly affected by things that we aren’t remotely aware of.
But that’s not quite the same as asking the question of whether we are influenced by stimuli that are presented to us below our level of awareness. And it doesn’t answer the question of whether someone else could influence what we decide to eat for lunch without our knowledge by presenting us with subliminal stimuli, whether visual or not.
Emotional Reactions to Subliminal Visual Stimuli
One way to answer these questions is to study people’s emotional reactions to subliminal visual stimuli.
If someone is shown an upsetting picture normally, so that you can consciously see it, they’ll show emotional arousal that can be measured by recording physiological reactions such as your heart rate or galvanic skin response.
In fact, subliminal visuals such as photographs can also produce very distinct emotions. In various studies, flashing disgusting pictures subliminally increased participants’ feelings of disgust, and flashing subliminal frightening pictures increased participants’ feelings of fear.
Learn more about if subliminal messages affect behavior.
The Department Head and the Pope
The effects of subliminal visual stimuli can go beyond simply making people feel good or bad. In one well-known study, graduate students at the University of Michigan were presented with either a photograph of their scowling department head or a photograph of a smiling person.
These pictures were flashed for only two milliseconds—two!—that’s 2/1000’s of a second, and none of the participants reported seeing anything when they were asked. Then the graduate students evaluated one of their own research ideas, rating how original and important the idea was.
Results showed that the students rated their research ideas significantly more negatively if they had been exposed to the disapproving scowl of their critical department head than if they had been exposed to the smiling face of the other person. A 2-millisecond flash of a photograph that they didn’t even see influenced their ratings of themselves and of their research ideas.
In a related study, Catholic women at a Canadian university received subliminal visuals of a photograph of either the Pope, or another person they didn’t know.
The results of that study showed that women who reported that they practiced their religion on a regular basis rated themselves less favorably when the Pope’s picture had been subliminally shown to them. But their self-ratings were not affected when they saw the picture of the other, unknown person.
These two studies make a couple of important points. First, subliminal visual stimuli are processed at a pretty deep level. That is, even though participants didn’t consciously see the pictures, their brains could extract the identity of the person in the picture and even the nature of his facial expression. And second, subliminal photographs can affect not only our emotions in general, but also how we evaluate ourselves.
Common Questions about Visual Subliminal Stimuli
James Vicary claimed that he was able to increase Coca-Cola and popcorn sales in a movie theater by flashing subliminal visuals up on the screen telling the people in the audience to drink Coca-Cola and eat popcorn. Vicary claimed that he was able to increase popcorn sales by 58 percent and Coke sales by 18 percent.
A subliminal visual stimulus is a stimulus, such as a photograph or a written word, that we cannot consciously perceive.
There’s no question that we are affected by things that we aren’t consciously aware of. You are certainly not aware of the processes inside your brain that led to your thoughts and behavior.
Studies on subliminal visual stimuli indicate two things. First, visual subliminal stimuli are processed at a pretty deep level. And second, subliminal photographs can affect not only our emotions in general, but also how we evaluate ourselves.
