ISU Headlines

Scientists’s efforts to influence public opinion have limited effect according to study co-authored by Idaho State University Professor Carlisle

Posted September 9, 2010

Scientists' efforts to influence public opinion have a limited effect, according to a study published this month that was co-authored by Idaho State University Assistant Professor of Political Science Juliet Carlisle.

The study also notes that more people are likely to believe scientific studies claiming that oil drilling is riskier, not safer, than was previously thought, according to a new study of attitudes in California.

The study "The Public’s Trust in Scientific Claims Regarding Offshore Oil Drilling" appeared in the journal Public Understanding of Science published by SAGE. It was co-authored by Jessica Feezell and Eric Smith, both from the University of California, Santa Barbara, together with Kristy E.H. Michaud from California State University, Northridge and Los Angeles media consultant Leeanna Smith. The authors think that prior beliefs may turn out to play a critical role in many policy disputes, muting the influence of scientific studies.

"Although the focus of this particular study is offshore oil drilling, it is important that people understand that our findings can very likely apply to any number of policy issues," Carlisle said. "The concern is that if individuals are not open to ideas and information that contradict their prior beliefs and core values, not only do scientists have a challenging task, but also the open debate and marketplace of ideas that we value as a democracy is limited."

"This is not a conclusion that is likely to bring joy to the hearts of the scientific community," says Smith. But how do people decide which scientific claims and which experts to believe?

Some social scientists hold that people most often believe claims by experts from organizations that line up with their own personal political views – this is the source credibility hypothesis. An alternative view – the content hypothesis ­– claims that people are most likely to accept a scientific claim if it supports their existing views, regardless of the source.

Psychologists have been looking at these hypotheses since the 1950s, but in recent decades the content hypothesis has been all but forgotten in policy research. The investigators behind this PUS paper believe its time for a content hypothesis revival – specifically when it comes to views on offshore oil rigs.

The researchers used an experiment embedded in a 2002 public opinion survey of 1,475 Californians to assess the confidence people have in reports about safety studies on offshore oil drilling along the California coast. Californian voters are well versed in the debate about oilrig safety: resistance to offshore oil drilling began in response to the very first offshore operation in California in 1896 and has been political hot potato ever since.

The first important finding was that consistency between the content of messages and a person’s prior beliefs has a substantial impact. But the message source had no effect on peoples' confidence in the scientific reports: liberals have overwhelming confidence in the claim that offshore oil drilling is riskier than previously thought, irrespective of the source, and conservatives place more faith in the message that oil drilling is safer.

Given that liberals are generally pro-environment and conservatives are generally pro-development, this is exactly what the content hypothesis would predict: the ideology and the content of the message interact.

"One finding immediately jumps out. Californians generally have more confidence in expert claims that offshore oil drilling is riskier than previously thought than they have in claims that it is safer. Fifty-eight percent of the respondents express a great deal or moderate amount of confidence in expert claims that offshore oil drilling is riskier than previously thought," says Smith.

Together, these findings raise the question of whether scientific studies are likely to have much impact on the public’s views of the safety of energy sources.

The findings are consistent with previous research showing that core values and prior beliefs influence whether people accept persuasive messages. But this is the first time the researchers are aware of to show that core values and prior beliefs have independent effects.

If researchers can replicate these findings in other policy areas, the influence of science on public policy debates will be in doubt.


Contact: Juliet Carlisle, ISU Political Science Assistant Professor, (208) 282-2550 or; or Jayne Fairley, SAGE,, Tel: +44 (0)207 3248719. Note: Most of the information in this press release was provided by SAGE in a press release written by Jayne Fairley that was distributed for release on Sept. 3.

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