1. Introduction
4, There is a growing body of literature claiming that many of the world’s leading causes of death are preventable. A classic example illustrating this point is coronary heart disease (CHD), responsible for about 9 million deaths worldwide in 2019, substantially more than the approximately 7 million deaths two decades ago [ 1 ]. Even when such statistics are adjusted for temporal changes in the age of the population, CHD is still the number one cause of mortality, killing about 83 Americans every hour [ 2 ]. According to meta-analyses focusing on CHD prevention, a significant proportion of these deaths could have been prevented or delayed by various health-promoting behaviors (HPBs) such as physical activity [ 3 5 ], healthy diet [ 6 7 ], and improved stress management [ 8 9 ]. Naturally, CHD is not the only major cause of death that could be reduced through improved decision-making and lifestyle changes. Some cancers are also preventable through public health interventions [ 10 ]. Moreover, even COVID-19, which has had a profound impact on society in recent years, can now be significantly mitigated due to recent developments in understanding how the disease is spread and how the public can be inoculated against the virus [ 11 12 ]. However, it is far from given that public health interventions aimed at promoting beneficial behaviors and curbing these diseases are indeed successful in influencing lifestyle choices and informing health decisions. For example, the prevalence of obesity in the United States continues to rise sharply despite numerous attempts to address this problem [ 13 ]. Similarly, recent studies conducted on large samples show that approximately a quarter of US citizens do not plan to get vaccinated against COVID-19 despite various public health campaigns highlighting the safety and efficacy of available vaccines [ 14 ]. This number is even higher in some other countries; for example, as of July 2022, almost half of the Romanian population and two-thirds of the Bulgarian population have not yet been fully vaccinated against COVID-19 [ 15 ].
It is well-known that decisions related to health, such as the decision to be vaccinated, are notoriously complex and influenced by many factors [ 16 ], leading to several models that aim to explain the variability in individuals’ behavior. One of the most widely cited and empirically supported is the Health Belief Model, which consists of four factors that determine the likelihood of engaging in HPB—perceived susceptibility to a condition, perceived severity of contracting an illness, perceived benefits of performing actions available to reduce the threat, and perceived barriers to undertaking the recommended behavior. These four components are influenced by cues to action (e.g., mass media campaigns) as well as the modifying factors (e.g., personality and knowledge) [ 17 ]. In the present paper, we focus on three modifying factors that could facilitate or hinder engaging in HPB. Specifically, we argue that people are less likely to benefit from public health campaigns and adopt behaviors that would benefit their health if they: (1) do not understand the general science (or evidence) on which they are based; (2) do not trust the primary source of evidence (i.e., scientists); (3) have difficulties obtaining, processing, and applying health information specifically.
28, The first factor, scientific knowledge or scientific literacy (1), is often regarded as a synonym with public understanding of science and generally includes components such as knowledge of the substantive content of science and the ability to distinguish it from nonscience [ 18 19 ]. Although empirical studies of its relationship with HPB are scarce, often indirect, and inconclusive [ 20 21 ], improved decision-making in the context of health is hypothesized to be an important micro-level benefit of high scientific literacy, as decisions in this domain often demand some understanding of science and its processes [ 19 22 ]. The second factor, trust in science (2), refers to the extent to which individuals believe that scientific claims are honest and accurate reflections of researchers’ work [ 23 ]. While this variable has traditionally been used as an outcome, not as a predictor, recent studies related to COVID-19 identified trust in science as one of the critical variables that determine individuals’ compliance with COVID-19 prevention guidelines [ 24 25 ]. The third factor, health literacy (3), is set explicitly in the health context (not science in general) and should not be equated with scientific literacy. Instead, it generally includes aspects such as basic health knowledge, applying this knowledge to make health decisions, as well as skills and motivation to find, use, and assess the validity of health information [ 26 ]. Higher health literacy is consistently associated with better health outcomes, including higher indulgence in HPB, and is, thus, considered one of the critical public health goals [ 27 29 ].
21,24, Although all three factors described above could play an essential role in determining health decisions and lifestyle, the existing body of knowledge has several shortcomings. First, only a few empirical studies [ 20 25 ] have investigated to what extent scientific knowledge and trust in science are individually related to a wide array of HPBs. Second, due to the lack of studies exploring all three factors simultaneously, in a single study, it remains relatively unclear whether they exhibit similar patterns of correlations with HPB (and other variables of interest), how they compare in terms of the strength of association with HPB, as well as how they relate to each other. Third, though the variables are theoretically related yet distinct, it is not clear if (or how) they interact to form subgroups of individuals who are at exceptionally high risk in terms of their health outcomes.