As noted earlier, research on public perceptions of science has shifted over time. Although earlier work focused on public knowledge of facts, more recent work emphasizes how people understand the practice of science. Recent research on public understanding of science has begun to assess what people know about how scientists perform scientific research (Hendriks, Kienhues, and Bromme 2020). Scientists can vary in their methods of inquiry and the quality of that inquiry. At least some recent research has assessed the extent to which people tend to understand basic principles of scientific inquiry that are often taught in the context of higher education science training.

What Americans understand about the ways in which rigorous S&T research is conducted is also relevant to how the general U.S. population views S&T institutions and professionals. Knowing how well Americans understand the processes that S&T professionals use to make observations about the world can offer insights about the context of, and even potential explanations for, their general perceptions about S&T. For example, proactively acknowledging that uncertainty is an element of the scientific process because scientists continue to test ideas over time can encourage confidence in science in general (Druckman 2015; Jamieson and Hardy 2014).

Many Americans admit to not having much scientific knowledge when asked for their subjective report of how much they know. Data from the 2018 Wellcome Global Monitor survey found that 22% of Americans surveyed believed they knew “a lot” about science (Figure PPS-5). This was, nonetheless, a higher percentage than was reported by citizens of all other 15 countries with the largest gross domestic expenditure on R&D as a percentage of GDP except Denmark, which was not statistically different in the percentage reported. On average, 7% of citizens across all 16 surveyed countries said they knew “a lot” about science.

Recent evidence suggests a majority of Americans understand the nature of science as an iterative process of observation and testing, although a substantial number of U.S. adults do not view science in that manner. According to American Trends Panel data collected in November 2020 by Pew Research Center,^{​As noted earlier, the Pew Research Center provided restricted-use data from November 2020 for this analysis that are presented here and used with the center’s permission.} when asked which of a series of statements best describes the practice of science, a majority (66%) believed that the scientific method produces findings that are meant to be continually tested and updated over time, but a substantial minority of respondents (34%) believed that the process produces “unchanging core principles and truths” or was unsure (Table PPS-2). These results suggest that most American adults understand the possibility of changes over time in the empirical evidence generated by scientific research, but a third does not. At least some scientific knowledge reflects a relatively established body of evidence and does not change often, which some respondents might understand; nonetheless, the majority of respondents in the Pew Research Center study also acknowledged that science can include new studies to test established ideas.

The November 2020 American Trends Panel question regarding the iterative nature of science as an endeavor, while useful, does not directly assess how well people understand the specific contribution of any one scientific study to an overall body of evidence. It is possible that some people understand that scientific evidence can be updated and should be assessed multiple times and yet still do not understand, for example, that a crucial test of a hypothesis can add more useful evidence than many other types of empirical observations.

Additional evidence from the American Trends Panel reveals that a majority of adult Americans have some substantive understanding of experimental logic and could correctly note that a control group can be useful in making sense of study results (Table PPS-2). When asked, however, only half of U.S. adults surveyed could correctly identify a scientific hypothesis. Those results indicate that a sizable proportion of the U.S. adult population does not currently understand the scientific process of hypothesis testing in the same way that professional scientists working in scientific communities do.

Americans’ understanding of scientific logic and of the effectiveness of the scientific method is positively related to their confidence in scientists to act in the public’s best interests, which is an indicator of trust. Trust comprises not only perceptions of competence but also perceptions of shared interest between parties (Southwell et al. 2019). Data collected by Pew Research Center in November 2020 support a link between individuals’ understanding of science as a process and their confidence in scientists. Accurate understanding of the scientific process was positively associated with respondents’ expression of “a great deal” of confidence in scientists to act in the public’s best interests. For example, 44% of those who accurately reported that the scientific method produces findings meant to be continually tested and updated also expressed a great deal of confidence in scientists to act in the best interests of the public. By comparison, a lower percentage (29%) of those who held that “the scientific method identifies unchanging core principles and truths” expressed such confidence. In addition, half of respondents who agreed that the scientific method generally produces accurate conclusions expressed a great deal of confidence in scientists, whereas 15% of those who agreed that the “scientific method can be used to produce any conclusion the researcher wants” expressed a great deal of confidence in scientists “to act in the best interests of the public” (Table PPS-3).

In addition to asking about confidence in scientists generally “to act in the best interests of the public,” the November 2020 Pew Research Center survey asked a similar question regarding medical scientists. The pattern of responses regarding confidence in medical scientists was similar to confidence in science; those who had a greater understanding of science as a process tended to have higher levels of confidence in scientists generally and in medical scientists (Table PPS-3 and Table PPS-4). Among those who agreed that the scientific method generally produces accurate conclusions, 52% also expressed a great deal of confidence in medical scientists; among those not agreeing that the scientific method generally produces accurate conclusions, 17% expressed a great deal of confidence in medical scientists.