How effective are political campaign advertisements?

While the media buzz surrounding the 2012 Presidential Election is just starting up, now is as good a time as any to think about how effective political advertisements really are at influencing our candidate choices.  Every election season, political candidates shell out thousands and even millions of dollars on televised campaign advertisements.  But how persuasive are these advertisements really?  Previous scientific research in this area has only been able to look at how well individual’s reports of their media viewing correspond with their voting preferences.  However, a recent study by Gerber, Gimpel, Green, and Shaw (2011) addressed this question in a ground-breaking field experiment.  In the first large scale field experiment of its kind, the researchers were able to manipulate the timing and volume of televised advertisements for the incumbent candidate in the 2006 Texas gubernatorial election.  Furthermore, they were able to continually assess voter’s candidate preferences during the campaign season.  It was important that this study be conducted in the field because it is often hard in a laboratory setting to gauge how long-lasting the effects of media exposure are in real world settings.
The results of the study showed that the televised ads had a strong effect on voting preferences at first but that these effects did not last long.  The TV ads had a strong effect on voter preference or opinions about the candidates in the first week after individuals viewed the ads, a slightly smaller effect a week later, but they had virtually no effect after that.  In fact, only two weeks after having viewed the ad, the TV ad had virtually no effect on voter opinion!

So why did the effect of the advertisements diminish so rapidly over time?  Gerber et al., (2011) hypothesize that the psychological mechanism of priming can explain this effect in part.  Priming is the process of activating knowledge which can influence later memory of a related concept.  An example of this would be an individual viewing an ad where a candidate is seen helping others, and then later on recalling the candidate as a kind person or evaluating another candidate on their capacity to help others.  Therefore, the ads were effective in the short-run because they primed a certain image of the politician in the voter’s mind.  Furthermore, the decaying effects of advertisements over time are in line with the notion that as the cognitive accessibility (the ease with which an individual remembers something) of the prime diminishes so too does the effectiveness of the prime.

This timely study has many implications for political campaigns.  While we see an influence of the campaign ad in the short-run, in the long run the ad loses its effectiveness. This finding begs the question: how cost effective is it for politicians to spend millions of dollars on campaign ads which have little long-term effect on voter opinion?  Also, what types of ads would then be most cost-effective in changing voter’s preferences?  Keep these questions in mind when viewing the impending political campaign advertisements for the 2012 Presidential Election!


Gerber, A. S., Gimpel, J. G., Green, D. P., & Shaw, D. R. (2011). How large and long-lasting are the persuasive effects of televised campaign ads? Results from a randomized field experiment. American Political Science Review, 105, 135-150.