Cognitive Daily

The way subliminal advertising is portrayed in movies and hyped in some media outlets, briefly and imperceptibly flashing a brand name during a TV show can turn people into mindless cyborgs who can’t resist the urge to shop at a particular store or drink a certain brand of beer. Overhyped as these claims may be, there is a grain of truth in them — as a recent post in Neuromarketing points out, subliminal images really can affect our preferences:

In Your Money and Your Brain, Philip Zweig describes a study conducted by psychologist Robert Zajonc almost forty years ago. Zajonc exposed a two groups of non-Chinese-speaking subjects to a series of five Chinese ideographs; one group received five exposures to the symbols, while the other group just got one. In all cases, the exposures lasted only five milliseconds or less, too fast to be processed consciously. Then, Zajonc showed the subjects a larger group of images which included the original set as well as new ideographs and other symbols. The subjects were allowed to view the images for a full second, more than enough time to be conscious of seeing them, and asked how much they liked each one.

The subjects who received five subliminal exposures to an ideograph liked it much better than the subjects who had seen it only once.

So if we’re exposed to an unfamiliar image — even unconsciouly — we’ll say we like it more than people who’ve had less exposure to the same image. And scientists have known about this phenomenon for over 40 years! Does that mean we’ve been secretly brainwashed all this time?

I’d say that’s doubtful. After all, the question for advertisers isn’t so much whether multiple subliminal exposures is better than one or no subliminal exposures — it’s whether subliminal advertising is better than ordinary, in-your-face advertising. You see, there’s also plenty of evidence that ordinary advertising works.

If we’ve heard a message multiple times — even if that message came from the same source each time — we find it more reliable than a message we hear only once. So repetition works both subliminally and overtly.

What’s more, we’ve reported on research suggesting that overt repetition is more effective than subliminal repetition:

Listeners prefer the items they remember, rather than those they know–when they believe they recall hearing a specific excerpt, they like it better. Wang and Chang argue that this result supports the uncertainty reduction hypothesis. They suggest that we prefer things we’ve seen or heard before because these things are less likely to be dangerous: after all, if it didn’t kill us the first time we saw it, it’s probably safe.

Why would an advertiser risk charges of “brainwashing” and “subliminal suggestion” when good-old-fashioned front-and-center advertising is more effective? You don’t have to trick someone in order to affect their preferences. Sometimes the best method of persuasion is the most obvious one.


  1. #1 Johan
    October 24, 2007

    I had a post on this very topic a while back – my name contains the link.

    Two things to note about the mere exposure effect, and its applications to advertising:

    1. The effect is, even in the best of circumstances, modest. Repeated exposures beyond a certain point does not result in increased liking.

    2. The effect works primarily with novel and unfamiliar stimuli (such as the chinese symbols Zajonc used). This is no problem if you’re trying to raise awareness of a new brand, but it does mean that Coca Cola aren’t going to have much luck with subliminal ads.

    I can see certain very specific situations where subliminal advertising could work, but generally speaking, current overt marketing practices are likely to be far more efficient.

  2. #2 Ryan Fox
    October 24, 2007

    Perhaps you’re leaving some details out, or something, but shouldn’t they be using a control group that didn’t see it at all?

    Also, for the 5 flashes, was there much of a delay between each exposure? If you flash a lightbulb very quickly, (>100Hz) you won’t notice that it’s flashing; it’ll just look dimmer than normal.
    I realize that even if there wasn’t, 50 milliseconds (assuming 5ms on, 5ms off) still isn’t very long to be conscious of something. It might make a difference though.

  3. #3 Dave Munger
    October 24, 2007

    Excellent post, Johan. Thanks for the link.

    Ryan, I haven’t read the Zajonc study myself, but “subliminal” is by definition unconscious. Viewers are not conscious of having seen the image. I assume the repeated exposures took place separately, and they may have been mixed among a large number of viewings — so you don’t see one symbol five times in a row, you see it five times over the course of a long period of time.

  4. #4 scote
    October 24, 2007

    The body of studies seem to suggest that supraliminal stimuli are more effective than subliminal stimuli. There is a lot more to influence than what can be affected by subliminal exposures.

    On the opposite end of the spectrum, I was always amused at the position of Vance Packard, author of such fear mongering classics as “The hidden persuaders.” He thought that subliminal messages were much more powerful than overt ones. He even claimed that Playboy centerfolds were secretly implanted with subliminal text saying, literally, “SEX SEX SEX SEX…” Packard seemed to believe that clueless men wouldn’t have picked up the uber-subtle sexual implications of a 3 page spread of a naked woman without the super-powerful, subliminal text that informed them to think about “SEX SEX SEX.” I think it was at that point, reading his book in 6th grade, that I realized Packard was full of it.

  5. #5 Roy Huggins
    October 24, 2007

    Hey, Dave, don’t forget about musical overtures! The point of the operatic overture was to familiarize the audience with the main melodies in the upcoming show. Composers knew even hundreds of years ago that familiarity breeds catchy-ness, and also enjoyment of musical tunes.

    I would imagine that this is related to early advertisers relying so heavily on the marketing jingle.

  6. #6 Tim Byron
    October 25, 2007

    This youtube video of a segment of a show by British illusionist Derren Brown is very clever, and relates to your point about subliminal advertising.

  7. #7 cred
    October 25, 2007

    The experiment was done with exposure to neutral images (unfamiliar ideographs) and the conclusion is that those exposed to the image multiple “like” the image. But what if it wasn’t a neutral image? Suppose the image was of something culturally disgusting? I doubt the viewers would like or prefer that image. There have been many instances of advertising gone bad because they don’t translate culturally.

  8. #8 mute
    October 26, 2007

    having read other reviews of the zajonc study, i believe the main rationale was to show that you don’t need to understand or “think” about something in order to have a positive attitude towards it. it can happen automatically through affect (feelings) brought about by repeated exposure to the stimuli. the subliminal methods were merely to demonstrate that no conscious processing was necessary. thus its the exposure, however incidental, that is crucial more than the subliminality. thus, product placement.

    great site by the way.

  9. #9 acm
    October 26, 2007

    …you don’t need to understand or “think” about something in order to have a positive attitude towards it. it can happen automatically through affect (feelings) brought about by repeated exposure to the stimuli.

    anybody else think of ubiquitous radio hits? I mean, eventually overkill will make you hate some of them, but it’s pretty hard to separate “catchiness” from “this seems familiar” . . .

  10. #10 Stics
    November 20, 2007

    The Hoax – Celebrating 50 years with Subliminal Advertising.

    There are few stories in the area of marketing that have come to be as widespread and well known as the “Coca Cola – Subliminal Advertising” story. I thought it’s worth mentioning here that it is hoax. The story goes like:

    “This advertising specialist, Mr Vicary, comes up with a brilliant idea and inserts a brief advertising message into a movie but the message is so short that it will not be perceived consciously. The message “Drink Coke” and “Eat popcorn” constitutes a subliminal advertising message and is received by the audience at a sub-treshold level. In the pause, the sales of Coke and popcorn increased dramatically.” End of Story.

    This story is every now and then surfacing in media or among the general public, it can be heard from students, marketing researchers, advertisers and sadly enough, by many professors and professional researchers. What few know is that the “Jim Vicary Hoax” might as well be dubbed the No. 1 Myth in Marketing. It is by far the most well known phenomenon related to marketing that people in general knows about. And that they think is true. Nonetheless, the concept of “Subliminal advertising” is unsubstantiated. (See references below)

    Jim Vicary whose advertising agency, at the time, was not doing very well came up with the “experiment” and claimed that he had succeeded in advertising Coke and popcorn in an ingenious way. However, later when he was challenged and could not replicate or even produce the results, Vicary admitted that the results of the initial study had been fabricated (Weir, 1984). Furthermore, later studies have never produced any scientific evidence of the phenomenon, on the contrary (Moore, 1982, Rogers & Seiler, 1994, Percy & Elliot, 2005).

    Then, what is this so called “Subliminal advertising” all about? “Subliminal advertising” is defined as advertising that employs stimuli operating below the threshold of consciousness. It is supposed to influence the recipient’s behaviour without him/her being aware of any communication taking place.

    Those talking about the Subliminal effect are mixing things up! It is worth to notice that one should not, like many do, confuse the term subliminal with unawareness. Unawareness of the impact of an advertisment is something completely different than the “Subliminal”-concept. For instance, a person may read an article in a newspaper and next to the text is an advertisement for a product. Now, in this case the reader will be exposed to the advertisement perhaps even for minutes and the peripheral vision will capture parts of what is advertised as the eyes of the reader is being scanned back and forth over the text for a long period of time and also covering the ad at times. Clearly this does not have anything to do with the claimed “subliminal effect” but when studying the advocates of “Subliminal advertising” some are confusing Subliminal with unconscious. Another example frequently used is the small ice cube lady in a glass of whishy or any other drink. In this case some are arguing that it is “Subliminal advertising”. A notion that is somewhat difficult to understand. In cases like this the small pinup girl wearing bikini in the glass is clearly visible if you take the time and look. So in what sense is that “Subliminal advertising”? And what do the advocates of “Subliminal advertising” expect to happen? That the customer runs and buys a bikini?

    So why has “Subliminal advertising” gotten so much attention then? To understand that, things has to be put into context. There may actually be some answers.
    a) The book “The hidden persuaders” by Vance Packard from the end of the fifties was successful in stirring up peoples feelings. In his book he is sketching how consumers are manipulated, with advertising, into a consumption prison to the benefit of the companies.
    b) During this era, 50s – 60s, when the cold war was raging and senator McCarthy was at his peak some people and some very specific organizations were very concerned about whether methods like “Subliminal advertising” and the like could be used for political propaganda as a hidden weapon.
    c) During the 60s, 70s and up to the mid 80s the concept of hypnosis and subconscious effects were widely popular. Perhaps you may even remember TV-shows from this time where psychologists or “magicians” were hypnothising people live making them do funny things. The concept of “Subliminal advertising” and all the myths connected to it fit very well into this time period.
    d) “Subliminal advertising” is interesting because it tickles our imagination! The very concept of “Subliminal advertising” challenges our free will. It is manipulating us and worst of all, it is obscured or hidden so we do not know if or even when we have been subjected to it… and that may perhaps be the number one reason why this marketing myth is still alive and continuous drawing attention to itself.

    This year (2007) it is 50 years since Jim Vicary conducted his infamous “experiment”. Today Vicary’s story has unfortunately developed into folklore. But what is worse is that the general public as a consequence of this has a serious misperception of marketing and advertising.

    //Patrik Nilsson

    © Copyright 2007: Stics. This article may not be re-produced (in full or part) in any format/media off-line or Internet based, without prior permission from Stockholm Institute of Communication Science.

    Find more on this topic in the following references:

    Sheri J. Broyles, (2006), “Subliminal Advertising and the Perpetual Popularity of Playing to People’s Paranoia.” Journal of Consumer Affairs, Vol. 40 Issue 2, p392-406

    Dichter, Ernst (2007), “It was rubbish then, it’s rubbish now” Advertising Age; 9/10/2007, Vol. 78 Issue 36

    Moore, Timothy E. (1982). Subliminal Advertising: What You See Is What You Get. Journal of Marketing. 38-47.

    Rogers, Martha; Seiler, Christine A. (1994), “The answer is no: A national survey of advertising industry practitioners and their clients about whether they use subliminal advertising”, Journal of Advertising Research, Mar/Apr, Vol. 34 Issue 2

    Weir, Walter (1984), “Another Look at Subliminal ‘Facts’.”, Advertising Age

  11. #11 Stics
    November 20, 2007

    In discussions of Subliminal Advertising the research of Zajonc is often brought up. The reason for this is that the effects that he observed frequently are perceived to have similarities with “Subliminal Advertising”. A notion that is fundamentally inadequate. Zajonc’s ‘mere exposures’ has been discussed by for instance Mandler, Nakamura and van Zandt (1987) and also by Monahan, Murphy and Zajonc (2000). In their studies, repetition of ‘mere exposures’ may have the potential to produce a kind of vague feeling of familiarity that later could be interpreted as liking. Their studies are though, not studies of “Subliminal advertising”.

  12. #12 Patrik
    December 10, 2007

    Given the origin and the negative connotations associated with the term “Subliminal Advertising” or any other Subliminal phenomenon it might as well be better to re-define the terminology. A number of vaguely defined terms are being used in discussions of subliminal effects. For instance, that information are being received unconsciously, subconsciously, not consciously, without awareness, unintentionally, below the attentional threshold or some other related description.

    From my point of view an organism can either receive a stimulus or it cannot receive it. And there is of course an entire spectra of levels in between receiving and not receiving. Where the “real” threshold is, is of course an interesting area to study. That is, how faint a stimulus can be before it becomes subliminal. From this last sentence you can deduce that my position is that subliminal stimuli should not, in any way, be registered by an organism. Otherwise the stimuli is not subliminal.

    There is something paradoxical with researchers studying a phenomenon that according to the definition of the studied phenomenon should not generate an effect in the organism and thereby the researcher should not be able to measure any effect.

    Consider this; you are studying the phenomenon of subliminal advertising, subliminal messages, subliminal marketing, subliminal smells or the like. At the same time, as a researcher you are aware of the fact that the very concept of “subliminal” means that whatever stimuli is being used it will be insufficient as a stimuli. That is, since it is defined as subliminal it will be below the threshold of having any effect on the human brain. Consequently it would be more honest as a professional researcher and more adequate to state, contrary to most studies I have seen, that “after conducting this study we actually found that there indeed is a response (in some way) in the nervous system from the input used in the study, hence the input used does not qualify as a subliminal stimulus”. Or that “we found that there was no effect, hence the stimulus can be considered as subliminal.”

    The point is that a stimulus that generates a response should not be termed subliminal, at least not by professional researchers.

    It is my sincere suspicion that some researchers use the word “Sublimnal” for PR reasons in order to get more media attention for their research. Insert the word subliminal and you will automatically get less informed journalists to write about your research with the Coke & Popcorn angle as a foundation. There is of course also the group of researchers, coming from other areas than marketing/advertising, that are unaware of that the original “subliminal advertising” of Coke & Popcorn was a hoax.

    //Patrik Nilsson

  13. #13 Ed Darrell
    December 24, 2008

    Robert Zajonc died earlier this month. I rather expected a tribute somewhere on this blog, as it seems to be an area y’all cover best on the ‘net.

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