Media primes have a dose response effect like poisons

People who are repeatedly exposed to a biased message often quickly disbelieve it according to new research published by the Journal of Communication Research this week.

A study of 351 psychology students has found that people tend to ignore a message up until they hear it they encounter it three exposures to it, achieve peak persuasion at six exposures but then its effect quickly diminishes towards almost nothing at about eight times (Arendt, 2015).

While communication scientists have empirically known about the intuitive relationship between dose and response for decades (Roskos-Ewoldsen, et al., 2009), this study shows the curvilinear relationship of increasing dosages for the first time. Of course caution should be used in interpreting too much into one study in any scientific area and further research is needed to replicate the results.


It would be particularly interesting to find out whether the trend continues towards a negative response with higher doses. I strongly suspect they would.

Much like in toxicology message ‘dose’ is clearly an important factor in effective communication. This study's author reminds us of 16th century scholar Paracelsus’ advice when it comes to ingesting chemicals that “All substances are poisons; there is none that is not a poison. The right dose differentiates a poison from a remedy.”

For those that aren’t aware even drinking too much water can harm and eventually kill you.

The frequency and intensity of a priming message and its effect on an audience is a fascinating area for communication researchers and practitioners alike. Back when I worked in Australian politics in the early 2000s Shadow Ministers were encouraged to keep repeating their lines in media interviews according what we called the vomit principle. This principle suggested that only when you had said a message so many times that you felt you were actually going to vomit would your audience start listening and acting on it.

This was partly a product the communication challenge of being in opposition and the inherent difficulty of making sure your audience at least had heard your message at least once, but nevertheless the research carries a cautionary tale for communicators - don't expect that the more times your audience hears a message the more they will be persuaded by it.

It is also a cautionary tale for the mass media, particularly those that seek to persuade their audiences through biased reporting. It seems that audiences will see through it quickly enough to be a real risk and may quickly backfire.

It also seems that when it comes to communication the dose really does make the poison - or the remedy. The challenge for communication professionals is knowing when to shut up.


  • Arendt, F., 2015. Toward a dose-response account of media priming. Communication Research, 42(8), pp. 1089-1115.

  • Roskos-Ewoldsen, D., Roskos-Ewoldsen, B. & Carpentier, F., 2009. Media priming: A meta-analysis. In: J. Bryant & M. Oliver, eds. Media effects. Advances in theory and research. New York: Taylor and Francis, pp. 74-93.