Hypodermic Needle Theory

The earliest definition of Hypodermic Needle Theory (HNT) comes from journalist Walter Lippmann’s book Public Opinion, saying that the growth of mass media culture has powerful effects on the minds and behavior of people (Lippmann, 1922). Although there was no actual evidence to back up his argument, his claim is the earliest version of HNT and that mass media can directly influence behavior in the same way a needle can directly affect a body (Danesi, 2013). It can also be called the magic bullet theory or the direct-effects model and is the concept that powerful media affect weak audiences (Campbell, 2017).

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Harold Lasswell

The American scholar Harold Lasswell supported the idea of HNT in his Propaganda Techniques in World War I (1927) saying that mass-mediated propaganda affected the politics, family relations, general outlooks, and behavior of people. He summarizes why and how effective mass propaganda was in World War I, particularly in Germany’s case. Since mass media/propaganda was so effective during the war, it supported HNT and that people respond directly to mass media messages.

The main opposing argument to HNT comes from Paul Lazarsfelds’s The People’s Choice: How the Voter Makes Up His in a Presidential Campaign (1944) where he describes limited effects theory. Limited effects theory says that mass media do have effects on a person, but not directly like HNT proposes. First, the theory says media rarely have direct influence on a person because most people are sheltered from manipulation by family, friends, coworkers, or social groups. Second, there is a two-step flow of communication. Opinion leaders, critical media users that are not easily manipulated, spread information from the mass media to others, and they act as effective media influence barriers. Third, by adulthood most people have formed strong communities, such as political parties or religious affiliations that may reject the media messages. Which would cause a person to also reject the messages. Lastly, when media effects do occur, they are mostly small and isolated. It is easier for smaller groups of people, or weaker communities to be influenced, but not the masses (Danesi, 2017). This is the main counterargument to HNT and scholars conduct studies or observe life events to try to either agree or disagree with the two opposing theories.

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Illustration to HG Wells’s War of the Worlds

HNT was in speculation until in 1938 the radio broadcast of Orson Welles’s radio adaptation of H.G. Wells’s novel War of the Worlds aired. The novel was about an alien invasion of Earth and there were several disclaimers throughout the broadcast stating that the story was fiction. However, many listeners thought the invasion was actually happening and there was mass panic where people even left their homes and called authorities. This led to the first psychological study of media effects (MEs), called the Cantril Study. In The Invasion from Mars: A Study in the Psychology of Panic (1940), Hadley Cantril, a Princeton University professor, and a team of researchers interviewed 135 subjects after the broadcast. The study gave empirical support to HNT when they concluded that the panic from the broadcast was real, even though many of the subjects were embarrassed to admit they thought the event was real (Danesi, 2017).

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Mass media effects are more powerful on children

The Cantril Study was criticized by many psychologists and sociologists as being flawed because it did not show a statistical correlation between the broadcast and the degree of reported panic. Also, panic may have been caused by media reports that purposely exaggerated the story. No deaths or serious injuries were reported after the broadcast and the streets were never crowded with panicking people. The panic recorded by the mass media was fictional. Although, the study still did prove that media produced effects on people, just not direct effects like HNT proposes (Danesi, 2017). HNT is disapproved by many social scientists, but many people still attribute direct effects to mass media, especially with children (Campbell, 2017). This led to more studies to determine the extent to which mass media impacts people’s minds and behavior (Danesi, 2017).


Baran, S., & Davis, D. (1995). Mass Communication Theory Foundations, Ferment, and Future. Belmont, California: Wadsworth.

Campbell, R., Martin, C.R., & Fabos, B (2017). Media & Culture: Mass Communication in a Digital Age 11th Edition. Boston and New York: Bedford/ST. Martin’s.

Cantril, H., Koch, H., Gaudet, H., Herzog, H., & Wells, H. G. (1940). The Invasion from Mars: A Study in the Psychology of Panic. Princeton: Princeton University Press.

Danesi, M. (Ed.). (2013). Encyclopedia of Media and Communication. Toronto, Buffalo, London: University of Toronto Press.

Lasswell, H. (1927). Propaganda Techniques in World War I. Cambridge: MIT Press.

Lazarsfeld, P., Berelson, B., & Gaudet, H. (1944). The People’s Choice: How the Voter Makes Up His in a Presidential Campaign. New York: Duell, Sloan, & Pearce.

Lippmann, W. (1922). Public opinion. Macmillan,: New York.

Image Attribution: The first image is in the public domain licensed under CC BY-SA 4.0. The second image used is illustrated by Frank R. Paul in the U.S. public domain. The third image used is in the public domain

Written by Jenna Follin, 2018


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