The brain is a mysterious and complex organ. It allows us to move and talk. Some experts say that the brain is also responsible for our self-awareness or consciousness. However, they are only beginning to pinpoint the source of human consciousness.
But people have understood subliminal perception for ages. Through subliminal messaging, people have been trying to influence others’ minds since at least the 5th century.
What Is Subliminal Perception?
Subliminal perception is your ability to pick up on information without really knowing it. We are constantly bombarded by stimuli. We see, hear, touch, taste, and smell the world around us. Sometimes, we can tell you exactly what that stimulus is. That’s an example of conscious perception.
But humans only process about 0.0004 percent of sensory influences. We assess the rest on a subconscious level. Our subconscious minds can process 20,000 inputs at once. The conscious mind can only process about 7 bits of information at a time.
Think about what happens when you drive home from work via the same route every day. You know that you’re watching the road because you arrive unharmed and don’t collide with anything. But you might not be knowingly aware of every twist and turn. Your mind processes the landscape around you, but you don’t consciously witness every landmark.
We process the majority of stimuli via implicit perception. These stimuli are important and influence your conscious perception. However, you just might not be able to verbalize what you experienced.
Subliminal perception is a subcategory of implicit perception. However, some of the stimuli that you pick up on with your implicit perception are completely perceptible. You could notice that there is a tree next to the white house with a dog standing beside it on your way home from work, but you don’t.
Subliminal perception involves processing information that is delivered below the threshold of awareness. In other words, it’s impossible to even try to consciously see, hear, feel, touch, or smell the stimulus because it’s imperceptible.
What Is the Absolute Threshold?
To understand subliminal perception, it helps to know a bit more about how we process information from sensations. Sensations are data that our sensory receptors take in. Perception is the way that the brain chooses, categorizes, and decodes the data.
Everyone’s sensory system is different. Our brains interpret signals from our sensory neurons differently than anyone else’s. The sensitivity of the sensory system is articulated via an absolute threshold. That threshold is the least amount of input that the stimulus needs to produce for you to detect it 50 percent of the time.
If a light is dim enough or a sound is quiet enough, you may only recognize it half of the time that it presents itself to you. You might even perceive it less than half of the time.
But our sensory neurons can be more sensitive than you think. Did you know that the human eye can detect light from a candle flame 30 miles away on a clear night? Subliminal perception falls below your absolute threshold.
However, a stimulus that is undetectable 51 percent of the time is still not subliminal. The subliminal message must be imperceptible to the majority of people almost all of the time. A subliminal message falls below the absolute threshold of one person or a group of people.
Understanding Sensation and Perception
Sensation and perception are related. Sensation is the process of experiencing our environment through touch, taste, sound, sight, and smell. Perception is the way that our brains process that information.
In other words, our senses collect information. We can pick up a lot of this data at once through our nerve endings. You might simultaneously experience multiple sensations through every input. When you step outside, you feel your weight on your feet, feel the breeze on your skin, see the sky and trees, and smell the scents in the air.
We use our perception to make sense of our sensations. Our perception adds emotions to sensations. It categorizes them as positive or negative, painful, or pleasurable. Our perception helps us navigate in a world of sensation.
When we’re bombarded with stimuli, we tend to minimize some and focus on others. We would be overloaded if we experienced everything at once. Our perception allows us to identify primary and relevant stimuli so that we can pick it out from the background noise.
Everyone perceives sensation differently. That’s why one person might feel pain from a pinprick while another shrugs it off. However, some patterns are similar across groups of people. For example, most people would refer to a line of dots as a row instead of “dots and more dots.”
In much the same way, most people have a similar level of awareness when it comes to subliminal perception. Some people may be more vigilant than others and could pick up a flash that someone else didn’t recognize. However, the most subtle subliminal messages are difficult for anyone to perceive.
How Can You Measure Subliminal Perception?
If subliminal perception is an awareness that’s below the threshold of consciousness, how can anyone measure it? How can we be sure that it’s real and not science fiction?
Many studies have shown that stimuli can affect your feelings, thoughts, and attitudes, even if you don’t realize it. If you think about it, you often feel a certain way without being able to pinpoint the source.
Scientists use objective and subjective measures of awareness to evaluate subliminal perception. For example, they may ask subjects to give self-reports of what they perceived or experienced. They may ask study participants to indicate whether they recognized a subliminal stimulus. If the answer is no, researchers may ask participants whether they thought the stimulus influenced their attitudes, emotions, or actions.
However, some people argue that you can never truly measure whether something influences someone on a subliminal or conscious level. Our brains are complex, and measuring perception is difficult.
The History of Subliminal Perception
Today, most people think of subliminal messages as unnoticeable flashes that appear on the screen while they’re watching something or incredibly brief sound bites that dot a piece of music or auditory piece. However, you might say that the Greeks used subliminal messaging in their rhetoric. In ancient times, magic and rhetoric went hand in hand.
To the Greeks, rhetoric was the ability to use verbal communication to influence others. Some believed that speech could be deceptive and manipulative. They considered certain words to be so psychologically influential that they realized that the perfect combination of words could cause someone to think a certain way.
Although this was one of the first hints of using “mind control,” it wasn’t exactly subliminal. Spoken or written words are perceived by human awareness. However, the intent and psychological consequences of hearing those words are perhaps subliminal. We don’t always know why something that someone says makes us sad or encourages us. It happens on a subconscious level.
In the 1800s, E.W. Scripture published “The New Psychology.” In this book, the basic ideologies surrounding subliminal messages were explained.
Researchers continued to look into the subject in the early 1900s. Psychology professor Knight Dunlap conducted an experiment to determine whether an undetectable shadow could influence viewers’ evaluation of the length of two lines.
The shadow flashed briefly as subjects were looking at an optical illusion that showed two lines of equal lengths but appeared to be different sizes because of the direction of arrowheads placed on the ends. Subjects apparently assessed the lengths of the lines differently when the shadow flashed.
Advertisers began to use subliminal messages in the mid-1900s. Words that appeared instantaneously during television programs were thought to persuade viewers.
In 1957, marketing researcher James Vicary looked at the way subliminal messaging influenced people in a movie theater. When phrases such as “Drink Coca-Cola” appeared for .0005 seconds during a movie, popcorn sales increased by 18 percent. When the words “Eat popcorn” showed up, popcorn sales went up by a whopping 58 percent.
Although Vicary later admitted that he made up the study (he never showed evidence to prove that he had conducted the research), people were intrigued. They were also concerned.
If humans can be swayed by subliminal messages, how can they protect themselves? People worried that the government would target subliminal perception to get masses of people to do things that they might not normally do.
By the 1960s, scientists were aware that environmental stimuli could reach the brain within 20 milliseconds. They also realized that people could experience an emotional response to those stimuli before it entered their consciousness.
In 1980, Robert Zajonc led a study that proved the theory that people could be influenced by data that affected their subliminal perception but not their conscious minds. He presented his subjects with a stimulus that lasted for 20 milliseconds. The participants were able to judge the stimulus as positive or negative even though they couldn’t identify the stimulus itself.
In his article, “Feeling and Thinking: Preferences Need No Inferences,” which was published in the journal American Psychologist, he explained his study. He also used this information to highlight the importance of emotion in the human psychological experience.
Before this time, many psychologists eschewed emotion as an unimportant distraction to cognition. But if feelings come before your brain has time to process information consciously, then they must be more important than people think. That’s what Zojac concluded.
He went on to talk about emotions as energy that becomes encoded and dealt with in the body. This energy can take up space in the physical body independently of the way that we think of it with our logical brains.
Zojac believed that emotions were the most fundamental aspect of human existence. He was interested in the idea that our conscious minds raise the level at which we detect unwanted stimuli to protect ourselves. That theory suggests that we overlook intense stimuli that might not feel good to us. But for our conscious minds to block or delay the effect of that stimuli, our subconscious perception must filter it in some way first.
In other words, humans put up a “perceptual defense.” We unconsciously detect potentially harmful emotional content and use it to adjust the way that we process it in our brains.
For example, our skin temperature might change, or our heart rate might go up when we experience a stimulus that is expected to make us anxious. But our brains might tune it out to protect ourselves. Therefore, our autonomic processes might be construed as a component of subliminal perception.
This element of subliminal perception is vital to our survival. If we have to wait to process a dangerous situation consciously, it might be too late. Our subliminal perception and autonomic emotional responses act as a gate for our consciousness.
If your subliminal perception sets up your consciousness to respond in a specific manner, you might argue that it primes your brain for cognitive functioning.
Subliminal priming is considered to affect behavior outside of awareness. Through subliminal priming, exposure to an audio or a visual message before you have the opportunity to engage in a related behavior affect the choices that you make when you take action.
For example, let’s say that you hear the word “cancer” before you’re offered a cigarette. You might be less likely to smoke it. The priming becomes subliminal when you see or hear the word in an undetectable manner. For example, it may appear on a screen for fewer than 20 milliseconds.
Subliminal priming is different than other types of exposure because it occurs outside of memory. In many cases, your experiences shape your behavior. If you were in a car accident at a specific intersection, you might remember the event every time you encounter that spot. The memory might make you more likely to be vigilant during the drive. But subliminal priming affects you even though you can’t bring up a memory of the exposure.
Subliminal Mere Exposure
The mere exposure effect, or the familiarity principle, is a psychological phenomenon that explains why people acquire preferences based on their experience with things. You might be able to understand this by thinking about what happens when you hear a new song. The first time you listen to it, it just sounds like noise. You might not even like the tune.
Let’s say that you hear the song on the radio a few days later. Out of nowhere, you think, “Oh, I like this song!” Then, you realize that you have only heard the song once before. It was part of that new album that you played a few days ago. Your brain tells you that you like the song because you’re more familiar with it now.
Zajonc ran a series of experiments in the 1960s that proved the mere exposure effect. Moreover, he demonstrated that people make these preferential judgments without prior conscious exposure.
To do this, he repeatedly presented subliminal stimuli to his subjects. Even though the participants couldn’t always claim that they had noticed the stimuli, they showed a preferential bias toward it. Zajonc also presented detectable stimuli to his subjects. He noticed that people showed positive affect faster after being primed with subliminal than detectable stimuli.
This has significant implications for understanding persuasion. People have quick emotional responses to subliminal stimuli. They’re also more likely to feel confident about their judgments of the subliminal stimuli than detectable messages.
Therefore, we may not need to be able to rationally process ideas in our brains before we make decisions. Zajonc believed that decisions were similar to preferences. You typically choose the things that you like.
Other researchers expanded on this. At first, people thought that preferences could be evoked subliminally, but the subsequent emotion was always consciously detectable. However, further research suggested that subliminal priming can elicit an affective reaction. That reaction may not present itself as a feeling, but it almost always shows up as a preference.
Therefore, subliminal perception plays an enormous role in why people do what they do. It affects the decisions that we make and the actions that we take.
The way that you feel regarding something neutral may influence your decisions regarding a completely different matter. In one study, researchers asked subjects to look at people with neutral facial expressions and identify the individuals’ gender. What the participants didn’t know was that they were seeing subliminal messages. Within each image of a person, the researchers imposed happy, angry, or neutral facial expressions.
After viewing the faces, the subjects drank a sweet beverage. The participants who had seen the subliminal happy faces poured themselves more of the drink than the people who had seen angry expressions. When they were thirsty, participants were apt to pay twice as much for the beverage after seeing happy expressions than angry ones.
The volunteers also rated their emotional levels during this time. Even though the subliminal expressions that they had seen didn’t seem to affect their conscious emotions, they influenced the subjects’ behavior.
Does Subliminal Perception Drive Social Behavior?
Anyone who sells anything is interested in learning what makes people tick. If they can figure out how to influence people, they can meticulously design their marketing plans. Moreover, they won’t have to guess—they can ensure that their strategies will influence behavior the majority of the time.
Subliminal priming has been extensively studied for market research reasons. In the late 1900s, subliminal perception was the foundation for new industries. People put out audio courses that used subconscious messaging to help people lose weight, quit smoking, and enhance their confidence.
Because subliminal perception seemed promising for multiple reasons, the U.S. Department of Defense sponsored a group of psychologists to provide a report on subliminal suggestion techniques. According to the experts, there was no evidence that subliminal self-help tapes worked.
In some cases, the researchers provided subjects with tapes that had misleading labels. When the participants were asked whether they felt as though they had improved after listening to the courses, their claims were based on the information on the labels, not the subliminal messaging in the audio.
Still, people have debated for many years whether it’s possible to sway consumers’ decision-making behavior via subliminal perception. Many researchers still believe that subliminal messaging doesn’t produce long-term effects on people’s thinking or behavior.
But the fear still exists. Subliminal messaging in advertising is banned in several countries.
However, you could argue that we use our subliminal perception even when the messages aren’t subliminal. In today’s age of “get more done in a shorter time frame,” many people seem to run on autopilot. We don’t have a keen awareness of what goes on around us. We’re simply plowing through our routine every day without noticing the details of our experience.
Therefore, seeing a sign for the same brand repeatedly as we commute to our jobs could have some impact on our subliminal perception. We process it automatically, and we might not be able to describe exactly what we see. In fact, if someone asks us, “Have you seen that advertisement for the new perfume?” we might not be able to consciously recollect it.
We use our subliminal perception more frequently than we think.
Examples of Advertisers That Have Used Subliminal Messaging
Even though subliminal messaging in advertising isn’t legally banned in the U.S., it is considered misleading. It’s not protected by the First Amendment, and the Federal Communications Commission will rescind the license of any organization that broadcasts subliminal messages. However, there are plenty of examples of advertisers that have preyed on subliminal perception.
Premium Corporation of America, the manufacturer of the board game Husker Du, admitted to including single frames with the phrase, “Get it” in their TV ads in the 1970s. This incident compelled the FCC to forbid subliminal messaging in TV commercials.
Toward the end of the 20th century and the beginning of the 21st century, Marlboro was dealing with the same issue as many cigarette companies—it was having a hard time reaching the public through traditional advertising because people were cracking down on tobacco marketing.
Marlboro used to advertise on Formula 1 race cars. When tobacco brands were prohibited from displaying their logos on race cars in Europe, Marlboro attempted an innovative feat. It placed a bar code on the cars that it sponsored. When the cars were moving quickly, the bar code transformed itself into an image that was eerily similar to the Marlboro logo.
Even Coca-Cola unwittingly used sneaky advertising on a poster that the company used to promote its product in Australia in the 1980s. In this case, the imagery wasn’t exactly subliminal. Once you see it, you can’t un-see it. However, it’s difficult to detect. It’s tough to say whether your subconscious mind would pick up on it even if you weren’t consciously aware that it existed.
To check out the image, head to this Snopes article. The artist who designed the poster included the visual as a joke. Coca-Cola claimed that it knew nothing about the illustration before an observer pointed it out. The artist was subsequently fired and sued.
In 2007, a few viewers noticed that a McDonald’s logo showed up for a split second during an episode of Iron Chef America. A spokesperson from the Food Network claimed that the visual was a technical error. McDonald’s also denied participation in subliminal advertising. However, many people think it’s a little fishy.
Backmasking and Subliminal Perception
Some types of subliminal messages are somewhat “encrypted.” With backmasking, for example, an audio recording will communicate a recognizable message when it’s played in reverse.
This was a significant concern in the 1980s when the public was worried that bands were including violent or satanic subliminal messages in their songs. Although academics and law enforcement found no evidence that this was occurring, the idea of using backmasking as mind control freaked people out.
Some bands did hide messages in their songs, but the communication wasn’t satanic. For example, the Beatles and Pink Floyd famously included some innocuous, satirical, or playful lyrics on some of their albums. The words were only recognizable when the albums were played in reverse.
Although backmasking is considered to be a form of subliminal messaging, there is a question as to whether it can be perceived by the subconscious. Because backmasking involves words that are played backward, it’s practically impossible to perceive. Can our perception reverse the order of the sounds to make sense of it?
That’s not clear. With most music that includes backmasking, you can clearly hear the intended words when you play the recording in the other direction. Therefore, it’s more of a hidden message than a subliminal one.
Your subconscious is smarter than you may imagine. It makes sense of the world while your conscious mind is busy doing other things. Therefore, it can be affected by subliminal messages.
There are many theories as to how influential subliminal messages are. While some people worry that subliminal perception can be manipulated in a way that’s akin to mind control, it’s more likely that people are inclined to be persuaded in the direction that they’re already leaning.