How do we perceive risk?: Paul Slovic’s landmark analysis

By Sara Gorman

In the 1960s, a rapid rise in nuclear technologies aroused unexpected panic in the public. Despite repeated affirmations from the scientific community that these technologies were indeed safe, the public feared both long-term dangers to the environment as well as immediate radioactive disasters. The disjunction between the scientific evidence about and public perception of these risks prompted scientists and social scientists to begin research on a crucial question: how do people formulate and respond to notions of risk?

Early research on risk perception assumed that people assess risk in a rational manner, weighing information before making a decision. This approach assumes that providing people with more information will alter their perceptions of risk. Subsequent research has demonstrated that providing more information alone will not assuage people’s irrational fears and sometimes outlandish ideas about what is truly risky. The psychological approach to risk perception theory, championed by psychologist Paul Slovic, examines the particular heuristics and biases people invent to interpret the amount of risk in their environment.

In a classic review article published in Science in 1987, Slovic summarized various social and cultural factors that lead to inconsistent evaluations of risk in the general public. Slovic emphasizes the essential way in which experts’ and laypeople’s views of risk differ. Experts judge risk in terms of quantitative assessments of morbidity and mortality. Yet most people’s perception of risk is far more complex, involving numerous psychological and cognitive processes. Slovic’s review demonstrates the complexity of the general public’s assessment of risk through its cogent appraisal of decades of research on risk perception theory.

Slovic’s article focuses its attention on one particular type of risk perception research, the “psychometric paradigm.” This paradigm, formulated largely in response to the early work of Chauncey Starr, attempts to quantify perceived risk using psychophysical scaling and multivariate analysis. The psychometric approach thus creates a kind of taxonomy of hazards that can be used to predict people’s responses to new risks.

Perhaps more important than quantifying people’s responses to various risks is to identify the qualitative characteristics that lead to specific valuations of risk. Slovic masterfully summarizes the key qualitative characteristics that result in judgments that a certain activity is risky or not. People tend to be intolerant of risks that they perceive as being uncontrollable, having catastrophic potential, having fatal consequences, or bearing an inequitable distribution of risks and benefits. Slovic notes that nuclear weapons and nuclear power score high on all of these characteristics. Also unbearable in the public view are risks that are unknown, new, and delayed in their manifestation of harm. These factors tend to be characteristic of chemical technologies in public opinion. The higher a hazard scores on these factors, the higher its perceived risk and the more people want to see the risk reduced, leading to calls for stricter regulation. Slovic ends his review with a nod toward sociological and anthropological studies of risk, noting that anxiety about risk may in some cases be a proxy for other social concerns. Many perceptions of risk are, of course, also socially and culturally informed.

Slovic’s analysis goes a long way in explaining why people persist in extreme fears of nuclear energy while being relatively unafraid of driving automobiles, even though the latter has caused many more deaths than the former. The fact that there are so many automobile accidents enables the public to feel that it is capable of assessing the risk. In other words, the risk seems familiar and knowable. There is also a low level of media coverage of automobile accidents, and this coverage never depicts future or unknown events resulting from an accident. On the other hand, nuclear energy represents an unknown risk, one that cannot be readily analyzed by the public due to a relative lack of information. Nuclear accidents evoke widespread media coverage and warnings about possible future catastrophes. In this case, a lower risk phenomenon (nuclear energy) actually induces much more fear than a higher risk activity (driving an automobile).

Importantly, Slovic correctly predicted 25 years ago that DNA experiments would someday become controversial and frighten the public. Although the effects of genetically modified crops on ecosystems may be a cause for concern, fears of the supposed ill effects of these crops on human health are scientifically baseless. Today, although biologists insist that genetically modified crops pose no risk to human health, many members of the public fear that genetically modified crops will cause cancer and birth defects. Such crops grow under adverse circumstances and resist infection and destruction by insects in areas of the world tormented by hunger, and therefore have the potential to dramatically improve nutritional status in countries plagued by starvation and malnutrition. Yet the unfamiliarity of the phenomenon and its delayed benefits make it a good candidate for inducing public fear and skepticism.

There is a subtle yet passionate plea beneath the surface of Slovic’s review. The article calls for assessments of risk to be more accepting of the role of emotions and cognition in public conceptions of danger. Rather than simply disseminating more and more information about, for example, the safety of nuclear power, experts should be attentive to and sensitive about the public’s broad conception of risk. The goal of this research is a vital one: to aid policy-makers by improving interaction with the public, by better directing educational efforts, and by predicting public responses to new technologies. In the end, Slovic argues that risk management is a two-way street: just as the public should take experts’ assessments of risk into account, so should experts respect the various factors, from cultural to emotional, that result in the public’s perception of risk.

Sara Gorman is a PhD candidate at Harvard University. She has written extensively about HIV, TB, and women’s and children’s health for a variety of public health organizations, including Save a Mother and Boston Center for Refugee Health and Human Rights. She most recently worked in the policy division at the HIV Law Project.