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To know me is to like me III: Subliminal advertising

Subliminal advertising is less (read me) interesting than you think.

This post is in response to
To know me is to like me II: Accessibility

When you travel for work, you end up on a lot of airplanes. Often, that means some polite conversation with the person sitting next to you. As a psychologist, that conversation is a dangerous one, because eventually I get asked what I do. When I say that I'm a psychologist, people's initial reaction is that I have somehow been analyzing all of their deepest problems, or perhaps that I have been looking into their soul.

They are relieved (and perhaps a little disappointed) when I tell them that I study the way people think. But quickly, they find other questions about thinking that have always puzzled them. One of the most common questions centers on the effectiveness of subliminal advertising.

Something about subliminal advertising captures our imagination. The prospect that a flash on a screen could drive us to do something without knowing why seems to scare us.

So, it is worth talking a bit about subliminal advertising in the context of the topic of the last post on accessibility. (If you haven't read the previous post yet, go back and read it first. I'll wait...)


First of all, subliminal advertising shouldn't frighten you. There are all sorts of things in the world that affect your decisions, even though you are not aware of them. However, these things that affect your behavior without awareness all do it by changing the accessibility of concepts in your environment.

And that is basically how subliminal advertising can affect you. Subliminal means "below the threshold." Basically, subliminal things are items that you sense (with your eyes, nose, mouth, ears, or skin), but you are not aware of.

The main influence that subliminally perceived items can have on you is to increase the accessibility of concepts relating to those items. So, think about the classic example of subliminal perception. You are sitting in a dark movie theater, and suddenly a single frame of the movie shows an ice-cold Coca Cola. Movies flash by at 24 frames per second. That is too fast for you to identify anything you have seen in a single frame.

What can that ice cold Coke do to you? Well, imagine first that you have never heard of Coca Cola or seen a Coke ad. In that case, the flashed Coke will do nothing to you. You don't have a concept to activate.

If you have heard of Coke (and sadly, most of us have), then it will make the concept of Coke easier to think about. For most of us, most of the time, that will have little effect on our behavior. We often see Coke ads on TV, in magazines and at sporting events. Often, we're not even that aware of the ads, because we try not to pay attention to them. That means that the situation created by subliminal advertising in a movie actually happens to us all the time. And most of the time, we do not slavishly go out and buy a Coke.

When can subliminal advertising affect your behavior? A few things have to happen. First, you must be in a situation where you need to drink already. The flashed ice-cold Coke may then raise the idea of drinking a soda to the level that you notice you need a drink. At that point, you may decide to get a drink. That won't be driven by the subliminal ad so much as whether you feel like getting up and drinking. If you do, then you'll order a drink. You might be somewhat more likely to order a soda than usual having decided to get a drink. However, there are so many things in your environment between the subliminal ad and the point where you can get a drink that you probably won't be much more likely to buy a Coke than you normally are when you decide to get a drink at the theater.

So, really, subliminal advertising isn't so interesting. What is potentially more interesting (at least to me) is why people believe that subliminal advertising could work. But that is a subject for the next post.