Climate-skeptical statements start to seem more persuasive after just one repetition, even to the people most concerned about climate change, according to a new study.
“We are more likely to believe things we heard before, even if we only heard them once,” says study team member Norbert Schwarz, co-director of the USC Dornsife Mind & Society Center at the University of Southern California in Los Angeles. “It is therefore important not to expose people to false information in the interest of ‘balanced reporting’” about climate change, he says.
Schwarz and his collaborators set out to test which of two psychological phenomena is stronger when it comes to climate beliefs: motivated reasoning, the tendency for people to view information that confirms their current beliefs as true, or the illusory truth effect, the tendency for people to view things that they hear repeatedly as more believable.
The researchers conducted two online experiments, one with 52 people and the other with 120. At least 90% of participants in each experiment held the view that climate change is real and human-caused.
The participants first read a series of statements, a mix of climate skepticism, climate science, and neutral weather-related messages. After 15 minutes they read another series of such statements – half of which had appeared in the first set and half of which had not. Then they rated the statements on a 6-point scale from “Definitely True” to “Definitely False.” In the second experiment, the participants also classified each statement as climate-skeptic or science-aligned.
People who accept the science of human-caused climate change were more likely to believe statements consistent with these beliefs, Schwarz and Yangxueqing Jiang, Katherine Reynolds, and Eryn Newman of the Australian National University in Canberra report in the journal PLoS ONE.
But repetition of both climate-science and climate-skeptic statements increased the perceived truth of these statements to a similar degree, the researchers found.
“One single exposure to a false claim about climate change is sufficient to make it seem a bit truer later on,” Schwarz says. “That’s even the case for people who strongly endorse climate science and who can identify the claim as a climate-skeptic claim when explicitly asked.”
The illusory truth effect is well-known but has mostly been studied in the context of low-stakes everyday knowledge. Until now it hasn’t been clear how it would operate when in conflict with people’s ardent convictions.
“We thought that people who strongly hold beliefs aligned with climate science may be less affected than others,” says Schwarz. “That was not the case”
The current study only assesses how repetition affects what people believe to be true about climate change – not changes in behavior, Schwarz says. Further studies are also necessary to find out how the illusory truth effect operates in the context of beliefs about other hot-button issues like immigration and health care, as well as how climate skeptics react to repetition of climate-science evidence.
“Our follow-up work will explore whether there are conditions under which people who are strongly endorsing climate science are less vulnerable to the observed effect,” Schwarz reports.
Source: Jiang Y. et al. “Repetition increases belief in climate-skeptical claims, even for climate science endorsers.” PLoS ONE 2024.
Image: ©Anthropocene Magazine
