Thursday, November 27, 2014

Psychology Myths 4 of 5

Myth #4 Subliminal Messages Can Persuade People to Purchase Products 


       Before starting I want to make a distinction between influence and persuasion. According to the Merriam-Webster dictionary, influence is "to have an effect," and persuade is to cause someone to believe or to do something. Thus, if I show you an advertisement that tells you to buy Coca-Cola and you buy a Pepsi, whereas you would not have bought a Pepsi before, then the ad had an influence on you, but it did not persuade you.

(If you would like to learn more about this and other myths check out 50 Great Myths of Popular Psychology by clicking this link)

       It's not surprising when people outside a field believe its myths, but it becomes alarming when people starting their career think they are true. In the case of subliminal messages persuading people,  59% of a sample of psychology undergraduates believed in it (Brown, 1983) and a different researcher showed the gullible students to be the 83% of a sample (Taylor & Kowalski).

How did it start?

       Once upon a time, there was a writer named Vance Packard and in 1957 he wrote a book titled The Hidden Persuader. It was a hit. In it, Packard described the experiment and results of market researcher James Vicary. According to Vicary, he conducted an experiment in a movie theater at Fort Lee, New Jersey in order to experiment on subliminal messages. He claimed that he flashed messages so fast that they couldn't be perceived consciously. This messages told viewers to buy popcorn and Coca-Cola. Vicary asserted that the rate of sales increased from 18.1% to 57.8% (Love, "The Shocking Drink And Incredible Coke History Of Subliminal Advertising"). The public became obsessed with his findings and the idea that the they could be persuaded to do things without being aware about it. He later received heavy criticism. One of the problems was that he didn't submit his results to the critical examination of a scientific  journal. After being pressured, he confessed that he made up the results (Moore, 1992; Pratkanis, 1992). His admission didn't change the public belief.

Why is it so prevalent?

       There is a great variety of materials out there that try to take advantage on the gullible. They tell your conscious that you should buy their material that will help you unconsciously. (You know, instead of marketing outside of your awareness because it doesn't work). 

       There are books such as Subliminal Seduction written by a former psychology professor that state that there are blurred sexual images in ads that make you buy their products.


Or material that ridiculously tells you that subliminal messages can bring you money...

... or make you have a beach body, or can enlarge your breasts. 
                                                                             beach body confidence subliminal

What doesn't work?

       The idea of subliminal messages persuading buyers is a myth. When researchers tried to replicate this concept, they obtained results different from those claimed by Vicary (Eich & Hyman, 1991; Logie & Della Sala, 1999; Moore, 1992; Pratkanis, 1992). There were other interesting versions of this experiment. One of them was conducted by the Canadian Broadcasting Corporation (CBC) on a TV program. They told viewers they were going to conduct a test in regards to subliminal messages on a Sunday night. The message said "phone now." However, the 352 messages flashed did not increase the rates of phone calls (Lilienfeld, 2010). Nevertheless, there were some callers that asserted that the messages made them hungry and that they felt thirsty. Maybe they knew about Vicary's story.

       Moreover, there is another misconception towards the myth. This refers to the messages that can be heard backwards. Usually, people claim they can hear Satanic messages in heavy metal songs. Opponents of this type of music assert that the messages tell people to change their behavior towards a negative one. To test this claim Vokey and Read (1985) conducted an experiment.They played message backwards and participants reported hearing pornographic material. The funny thing is that the messages were not playing heavy metal backwards, but rather they were readings of Biblical passages.

       In the why is it prevalent section? I wrote how there are audios that contain subliminal messages that supposedly can alter things in your life. Until now, they haven't been debunked. The experiment done by Greenwald, Spangenberg, Pratkanis, & Eskenazi (1991) will serve as an example of why this is instead the illusory placebo effect. Greendwald and colleagues conducted a double-blind test of these audios with tapes involving memory and self-esteem boosts. Half of the sample was told they were getting the memory boosts tapes and the other half was told they were getting the self-esteem ones. However, half of the group that was promised the memory boosts received them, the other half received the self-help. The same thing happened with the other group. The group that was promised the memory boost reported that they felt that they, in fact, received an improvement in their memory. Even the part of the group that unknowingly received the self-esteem tape. The same thing happened with the other group. They claimed improvement on what they believed they received not on what they actually did.

What works?

       Unperceivable messages do not persuade us, but they do have an influence on us. For example, Epley, Savitsky, & Kachelski (1999) conducted an experiment in which they asked participants to generate ideas for a research project. The participants were exposed to either the smiling face of a co-worker or an angry picture of their supervisor. The group that saw their colleague rated their ideas higher than those who saw their boss.

       Another example, of unconscious influence is by priming. In this example, subliminal messages influenced verbal behaviors. Merikle (1992) showed  participants half of a word such as "gui-". He then asked them to guess the whole word. He found that the probability of choosing the word guide increases if participants are primed to the words related to it, such as direct, lead, escort. However, the probability of choosing guile increases if instead the sample is exposed to words, such as deceit, treachery, and duplicity.


       This is the first myth in the series that was created on purpose. Even though its creator later explained that subliminal messages cannot persuade buyers, the public continues to believe in it. In conclusion, these messages that cannot be perceived consciously do not affect our buying choices, but they can still influence us to a certain degree.

(Keep reading the blog :P)

Feel free to leave a comment, questions, concerns, or suggestions.


Brown, L. T. (1983). Some more misconceptions about psychology among introductory psychology students. Teaching of Psychology, 10, 207–210. 

Eich, E., & Hyman, R. (1991). Subliminal self-help. In D. Druckman & R. Bjork (Eds.), In the mind’s eye: Enhancing human performance (pp. 107–119). Washington, DC: National Academy Press. 

Epley, N., Savitsky, K., & Kachelski, R. (1999). What every skeptic should know about subliminal persuasion. The Skeptical Inquirer, 23(5), 40–46.

Greene, J. (2005). Education myths. Lanham, MD: Rowman & Littlefield. Greenwald, A. G., Spangenberg, E. R., Pratkanis, A. R., & Eskenazi, J. (1991). Doubleblind tests of subliminal self-help audiotapes. Psychological Science, 2, 119–122. 

Influence. (n.d.). Retrieved November 27, 2015, from

Lilienfeld, S. (2010). 50 great myths of popular psychology: Shattering widespread misconceptions about human behavior. Chichester, West Sussex: Wiley-Blackwell.

Logie, R. H., & Della Sala, S. (1999). Repetita (non) luvant. In S. Della Sala (Ed.), Mind myths: Exploring popular assumptions about the mind and brain (pp. 125–137). Chichester: Wiley. 

Love, D. (2011, May 26). The Shocking Drink And Incredible Coke History Of Subliminal Advertising. Retrieved November 27, 2015, from

Merikle, P. M. (1992). Perception without awareness: Critical issues. American Psychologist, 47, 792–795.

Moore, T. E. (1992, Spring). Subliminal perception: Facts and fallacies. Skeptical Inquirer, 16, 273–281.

Persuade. (n.d.). Retrieved November 28, 2015, from

Pratkanis, A. R. (1992). The cargo-cult science of subliminal persuasion. The Skeptical Inquirer, Spring, 260–272.

Kowalski, P., & Taylor, A. K. (in press). The effect of refuting misconceptions in the introductory psychology class. Teaching of Psychology

Vokey, J. R., & Read, J. D. (1985). Subliminal messages: Between the devil and the media. American Psychologist, 40, 1231–1239.