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Roundtable on Public Interfaces of the Life Sciences; Board on Life Sciences; Division on Earth and Life Studies; Board on Science Education; Division of Behavioral and Social Sciences and Education; National Research Council. Public Engagement on Genetically Modified Organisms: When Science and Citizens Connect: Workshop Summary. Washington (DC): National Academies Press (US); 2015 Jul 7.

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Public Engagement on Genetically Modified Organisms: When Science and Citizens Connect: Workshop Summary.

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2How People Think (about Genetically Modified Organisms)

“I want to assure you that the public is not irrational.”—William Hallman

We don't think the way that we think we do. How scientist communicate with members of the public is often misguided by many commonly held but erroneous assumptions about how people form opinions and make decisions. Workshop participants discussed evidence from a small, rapidly growing social-science discipline, the science of science communication, which debunks many of the commonly held beliefs. The presentations highlighted results of research on science communication and public perceptions of GMOs and other scientific subjects.


Scientists often blame science illiteracy, unscientific thinking, and distrust for societal debate about science and its applications, such as that on GMOs. Speakers Dietram Scheufele of the University of Wisconsin- Madison (UW Madison), Tamar Haspel a food and health journalist with the Washington Post, Dan Kahan of Yale University, Dominque Brossard of UW Madison, addressed these perceptions, myths, and the social science evidence that refutes them.

Myth 1: Knowledge Deficits Are Responsible for a Lack of Public Support of Science

The so-called knowledge-deficit model or familiarity hypothesis has two primary assumptions, said Scheufele. First, “if people were more informed, they would ultimately be more supportive of science”; second, “we need to go out and just get more knowledge in the system and then things will be better for science.” The knowledge-deficit model fuels many scientists' desire and efforts to increase the public's science literacy. Scheufele emphasized, however, that social-science research provides evidence that more scientific information or knowledge about an issue does not lead to greater public support of particular scientific findings, and may even produce the opposite effect. Kahan provided an example of that effect from his research on climate change and public literacy.3 Using National Science Foundation data on public science literacy and technical reasoning capacity, Kahan and colleagues found that when a person's political outlook is more liberal, concern about climate change increases as science literacy increases; however, if one's political outlook is more conservative, concern about climate change decreases as science literacy increases. In other words, increased knowledge was not a driver of public perception of risks associated with climate change. Why doesn't providing people with more information increase their support for scientific evidence on changes in the Earth's climate, the effects of GM crops on human health, or other areas of research? The answer is explained in part by motivated reasoning and confirmation bias4. Motivated reasoning occurs when information that fits one's beliefs is weighted more heavily than information that does not fit them, Scheufele explained. All people, including scientists, tends to engage in motivated reasoning. Motivated reasoning helps to explain why the same piece of scientific information can have different meanings to different people and in turn produce different outcomes, he stated.

Haspel shared a metaphor for motivated reasoning described in The Righteous Mind: the elephant and the rider.5 The elephant is the “sum total of our intuitions, our emotions, our cultural affiliations, our values, all things that are essentially not quite innate but that are operating below the level of our rational mind,” Haspel explained. Atop the elephant is a rider, and the rider represents our cognitive processing that is responsible for analyzing facts and reaching logical conclusions. A person's elephant more quickly decides what it thinks about an issue than the rider, she said. For example, “I love the idea that we will be able to feed more people more efficiently; or ‘yuck,’ this is a terrible idea—we are taking genes from one species and putting them into another.” Once the elephant has decided which way to go, it is difficult for the rider to change the course (Figure 2-1).

Figure 2-1. Making decisions about science.

Figure 2-1

Making decisions about science. Tamar Haspel used the metaphor of the elephant and the rider to describe how people make decisions. Although many believe that they make decisions analytically and rationally (the rider), in fact people usually make decisions (more...)

Our desire to confirm what we believe also emerges in what social scientists call confirmation bias. We seek out people, mass media, and other information sources that agree with what we believe, Haspel explained. And we tend to filter out information that conflicts with what we believe. People can also hear disconfirming information and respond by becoming more entrenched in their positions, she said. Finally, people tend to evaluate the credibility of experts according to the extent to which they agree with them. Confirmation bias “is pretty scary because it basically allows us to believe the only credible people are the ones who share our worldview. It becomes difficult to find a way to change your mind,” Haspel said.

All people have differing experiences, characteristics, beliefs, and values that affect how they weigh scientific information. Scheufele, Kahan, and Brossard all emphasized that motivated reasoning and confirmation bias can be seen in societal debates about many issues, such as the use of stem cells, climate change, fracking, and gun control. To illustrate that point, Scheufele described results of a study on the effects of religious and other personal values on public attitudes about embryonic-stem-cell research.6 Among the highly religious participants in the study, people who had more knowledge about embryonic stem cells were no more supportive of stem-cell research than people who had less knowledge. “It is not about their not knowing, and it is not about their not getting the science,” said Scheufele. Rather, what they do know they don't necessarily translate into a more favorable attitude toward stem cell research, he concluded.

What about GMOs? To set the stage, Brossard shared data from public-opinion polls over the last decade, which consistently show that roughly 10% of the American public favors the use of biotechnology in plants that produce food “not at all”, and another 10% finds it “very favorable.” In other words, there are “very vocal minorities, pro and con” that hold strong views, she explained. Roughly one-third of the American populace “does not care”— does not have sufficient time, energy, or interest to invest intellectual energy in the GMO debate, Brossard stated. Next, she noted that results of CBS/New York Times/60 Minutes/Vanity Fair7 and CBS/New York Times 8 national public-opinion polls in June 2012 and January 2013, respectively, show that of roughly two-thirds of the what concerns people most about GMOs in the United States are related to health (for example, risks of cancer or food allergies) and on whether genetically modified food is safe to eat and that “knowledge level accounts for a small amount of the variance in public attitude.” In short, risk perception is not determined by people's knowledge about potential hazards, Brossard explained. She added that people tend to assess risks posed by technologies, such as GMOs, on the basis of a combination of knowledge about the hazards and benefits and their potential to disrupt our lives in a manner that provokes personal outrage.

David Goldston, of the Natural Resources Defense Council, cautioned participants not to “overcorrect” for the deficit model. He emphasized that facts are important in political debates about scientific issues. “The idea that facts are irrelevant, I think, is a gross overstatement and a dangerous one. What makes it tricky,” Goldston said, “is that we do not know when and how and which facts are going to matter.”

Myth 2: Useful Public Debate Requires Citizens That Think Like Scientists

What does it mean to think like a scientist? We tend to believe that “scientists think logically, analytically, and dispassionately and that members of the public are more intuitive and emotional,” Kahan said. He added that scientists tend to believe that the public “overestimates more dramatic risks like terrorism” as opposed to more remote risks like species extinction due to climate change. “As people become better at the kind of reasoning that is characteristic of science, they don't converge on what scientists say, they just become better indicators of what people like them think about this issue,” Kahan explained.

Kahan discussed the extent to which orchestrated misinformation might explain why there is societal debate about science. That assumption posits that economically motivated interest groups are supplying misinformation to a credulous public. In fact, what appears to be the case, according to Kahan, is that people are misinforming themselves and are not using new evidence to update their beliefs and understandings. “You have a culturally motivated public that really is eager to find information that is consistent with what their group believes. They will even use their science comprehension and critical reasoning skills to do it.” The result of that motivated reasoning is that they create a demand for misinformation, Kahan said.

The irony of the myth that training citizens to think more like scientists would improve societal debate about science is that “scientists don't think like scientists,” particularly with regard to ethical, legal, or social implications of their work, Scheufele stated. To illustrate that point, Scheufele described research results from regularly conducted surveys and interviews with leading scientists about the societal and public policy interfaces of their research, such as risks, benefits, and the need for regulation.9 An initial review of the findings revealed that scientists believe that the greater the risks of a new technology, such as nanotechnology, the greater the need for regulation. However, further analysis demonstrated that the scientists' personal ideologies predicted their stances on regulation, even after statistically controlling for their field of expertise and their seniority in their field. “The idea that scientists can ask members of the public to think scientifically about the political or social implications of technology is naive because we, as scientists, do not do it either,” Scheufele concluded.

So how do we all think? People are cognitive misers, Scheufele said. We use mental shortcuts to process information. Beliefs—ideologies, values, partisanship, and others—serve as mental shortcuts, ways to judge information quickly, he said. Because “it is not possible to use all information available to make [all our] decisions,” we rely on low-information rationality; that is, it is rational for people not to seek all available information but to rely on beliefs, he said10. Brossard emphasized that mental shortcuts are healthy human responses to the multitude of decisions that need to be made.

Myth 3: The Public Does Not Trust Scientists

“Trust matters more than knowledge” with respect to whom people listen to about science, Brossard asserted. That is, people accept the message when they trust the messenger. She added that the dimensions by which a group is assessed as trustworthy vary. For example, businesses must build trust that they care and are paying attention to people, advocacy groups must build confidence in their knowledge and expertise, and government has to establish that it is honest and open, she explained. “Trust does not mean the same thing for everybody,” she summarized.

Some have argued that the root of problems in societal debates about science is a declining trust in scientists, Scheufele noted. However, he pointed out that data from the General Social Survey11 that demonstrate the percentage of Americans that express “a great deal of confidence” in the scientific community has remained roughly unchanged since the early 1980s (Figure 2-2). Scheufele's group's research on societal perceptions of nanotechnology indicates that university and industry scientists are considered among the most trusted sources of information on the technology.12

Figure 2-2. American's Trust in the Scientific Community, 1983-2010.

Figure 2-2

American's Trust in the Scientific Community, 1983-2010. Drawing from GSS survey data, the graphs compare trust in the press, trust in organized religion, and trust in scientists. American trust in the press and organized religion is lower and in decline, (more...)

Kahan has also studied whether there is growing distrust of science or scientists. He explored National Science Board (NSB) Science and Engineering Indicator results on American measures of attitudes toward science, of whether people agree that the federal government should fund science, and of whether people think that the government funds scientific research too little or too much.13 Based on NSB data, Americans think that scientists are public-spirited, help to solve challenging problems, and are trying to do good on behalf of society. Kahan and his colleagues also examined the degree to which people trust scientists by presenting people with profiles of people who are experts in particular scientific issues.14 They measured participants' cultural outlooks. Current theory predicts that how people form their ideas about risk and strengthen their commitment to groups will reflect their cultural outlooks. Knowing that people differ on those dimensions, they presented half the study participants with profiles of scientists who took positions that indicated high risk and half with profiles that indicated low risk—that is, climate change is certain, is human-caused, and has dire consequences vs it's too early to say, and the models are inconclusive. They found that participants tended to consider someone an expert that they would listen to if the person's position was consistent with their own cultural outlook; otherwise, they dismissed the views of the person. However, none of the study participants believed that their views were inconsistent with the scientific consensus. Kahan concluded that people trust scientists, “but they are motivated to see that what science says is consistent with what their group says.”


William Hallman of Rutgers University described how people, in making different types of decisions, are guided by their worldviews, social comparisons, and concern with self-presentation. Hallman explained that people often overestimate how much they know about a subject, decreasing the likelihood that they will seek more information, but still form opinions that only become more ingrained as they act on them. He suggested that what some scientists want to know is whether members of the public can reach the right decisions about GMOs. “My answer is yes, but it depends on what your definition of right is.”

Decisions about What

Hallman said that the first step in understanding how consumers make decisions is to ask, Decisions about what? What kind of decisions? He explained that people make three basic types of decisions: decisions about truthfulness of facts, evaluative decisions, and behavioral decisions. To examine how people make decisions about truthfulness, Hallman and his colleagues conducted surveys to examine consumers' beliefs about GMOs.15 They asked 1,148 adults selected from a representative panel of American consumers to rate the truthfulness of claims about GMOs commonly found on the Internet on a scale ranging from definitely true to definitely false or “I don't know”. Nearly 70% of the survey participants did not know whether the claims were true or false, Hallman said. The survey results demonstrate that people have a great deal of uncertainty and are unable to detect whether claims about GMOs are factual, he stated.

Evaluative decisions require people to weigh the risks and benefits associated with GMOs, Hallman explained. Even though many Americans do not have a good understanding of what GMO means or what the technology entails, they still make evaluative decisions about it, he said. For example, many people who respond that they are not in favor of using genetic modification to create new kinds of plants respond in the same survey that they would be in favor of creating trees that can clean contaminated water or of creating more nutritious grain to feed people in developing countries. Decisions that require people to determine how consistent a technology, another person, or a corporation is with their values, worldviews, or ideologies involve another type of evaluative decision, Hallman explained.

Behavioral decisions are about whether to act. Voting on a referendum to label genetically modified foods, buying a product because it is labeled “GMO-free”, and protesting a local supermarket that carries genetically modified corn are behavioral decisions, Hallman noted.

People use several overarching types of mental shortcuts to make all three types of decisions, Hallman said. One is their general worldview, such as their views on “naturalness” or beliefs about the fallibility of humans. Another involves making social comparisons on the basis of group norms; this involves considering what decisions about an issue others have made to determine what to think or do. Finally, people are affected by their desire to be seen in particular ways to fit into a social or cultural group; this shortcut focuses more on self-presentation that is consistent with the group than on the “truth” of an issue. Motivation and the ability to digest and consider factual information influence how much one relies on mental shortcuts, according to Hallman.

Reality Filters

People have different perceptions about science and therefore often reach different decisions related to science. Hallman explained that people generally overestimate how representative their own knowledge and beliefs are of those of the whole population. When they see that others have reached different conclusions, the natural human response is to either question others' competence or motivation. Hallman indicated that although that is a human tendency, the idea is especially reinforced in science. The scientific method itself is based on the idea that if assumptions, methods, and data are explained, the same conclusions should be reached. When they are not, assumptions, methods, and data are reexamined. However, that is not how people think in their day-to-day lives, Hallman suggested: “One of the things I often hear from my science colleagues is that the public is certainly just irrational. But I want to assure you that the public is not irrational. They actually do have a basis for their decisions. They are just different from the ones that natural scientists have.”

All people, including scientists, Hallman said, use four filters of reality: literacy, graphicacy, numeracy, and ecolacy (Box 2-1).16 He explained that most people learn and communicate through literacy—stories, anecdotes, metaphors, and so on. However, he noted that the ability to take meaning from words and stories is culture-specific. Cultures often have their own “kinds of myths and kinds of references points” that may not be understandable to people in other cultures. Graphicacy—as related to sketches, photographs, diagrams, maps, and other forms of visual imagery—is also often culture-constrained, Hallman said. For example, the skull and crossbones represents danger to some, but child-poisoning studies demonstrate that the image doesn't intrinsically indicate poison.

Box Icon

BOX 2-1

Four Filters of Reality. Literacy: the ability to understand the meaning of words and stories. Graphicacy: the ability to learn graphic (visual) information.

Scientists often use a numeracy filter in their research. Laypeople may struggle more with mathematical concepts, particularly with very large and very small numbers, fractions, proportions, percentages, and probabilities, Hallman explained. When scientists communicate through numbers while journalists and other nonscientists communicate primarily through words and images, a communication barrier can arise. Numeracy barriers can exist even between scientific disciplines, he added.

The ability to see “the big picture” and the capacity to envision intended and unintended consequences of a decision or action are encompassed by ecolacy. Hallman implied that the ability to have a conversation about GMOs requires ecolacy within the scientific community and within diverse publics. However, he cautioned, being skilled in literacy, numeracy, and graphicacy does not equate to having ecolacy: “Just knowing a string of facts does not give you the ability to put them together to see the whole.” And that is why “educating people about the scientific details does not necessarily lead to greater comprehension of the big picture or the ability to make informed decisions.”


Hallman explained that all decisions have cognitive (thoughts) and affective (feelings) components. How people combine cognitive and affective components depends in part on the types of decisions that they are making. According to Hallman, many psychologists and economists believe that affect is a by-product of cognition; that is, people's evaluation of information leads to an emotional response. In fact, the opposite is often true, and this explains in part why first impressions matter so much. An initial emotional response affects later thinking. The pattern can also be cyclical: “I like it because it is good, and it is good because I like it.” People often have a poor understanding of what influences their perceptions and behaviors and of why they feel, choose, and act in particular ways. Furthermore, people often cannot predict what will make them happy in the future. In sum, it is erroneous to believe that thinking always comes before feeling, according to Hallman.

Findings from Hallman's 2013 survey demonstrate those complex relationships in Americans' ideas about and perceptions of GMOs. One set of questions asked respondents to rate their knowledge of how food is grown and produced in the United States and then presented a set of factual questions to measure their actual understanding. Although only 22% of participants rated their understanding as fair or poor, responses on the knowledge test indicate that people tend to overestimate how much they know. A consequence of the overestimation is that if people believe that they already know about a topic, they are unlikely to seek information or ask questions, Hallman explained.

The survey also revealed that 25% were not aware that genetically modified foods existed before they took the survey, 55% rated their own knowledge of genetically modified foods as little or none, and 66% had never had a conversation about GMOs with anyone. In addition, only 43% knew that there are genetically modified foods in supermarkets today, and only 25% believed that they were eating genetically modified foods. In other words, the survey results demonstrate that people “have not heard very much, they do not know very much, they have never talked about it, they are unaware that they are eating it, and yet they have an opinion,” Hallman summarized. In fact, about 50% of those surveyed admitted that their opinion of genetically modified foods was based on their “gut feeling” about it. Only 15% stated that their opinion was based on a specific issue, and 34% said that their opinion was based on both gut feeling and a specific issue. Hallman emphasized that “being uninformed doesn't stand in the way of having an opinion.” Most of the uninformed opinions are not strongly held, so they are subject to change. Nevertheless, they matter because people make decisions and act on the basis of them, he added.

Science issues involving food carry particular significance, and they are different from other science issues about which people make decisions, according to Hallman. Food is taken internally, and it also has symbolic value for nurturing and health and plays an important role in our relationships with others. Food is particularly susceptible to the “yuck” factor, the mental shortcut of disgust, he stated. Environmental technologies and even medicines, which are also taken internally, do not face the same challenges. This framework leads to the type of mental shortcut that can drive decision-making, Hallman concluded.



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Kunda, Z. 1990. The case for motivated reasoning. Psychological Bulletin 108(3):480-498.


Haidt, J. 2013. The righteous mind: Why good people are divided by politics and religion. New York, NY: Vintage Books.


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Copyright 2015 by the National Academy of Sciences. All rights reserved.
Bookshelf ID: NBK305772


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