Using risk model judgements to better understand perceptions of synergistic risks

Abstract

Numerous scientific studies show that risk factors can interact to synergistically increase the likelihood of certain adverse and life‐threatening outcomes. Yet, the extent to which individuals know that specific risk factor combinations present ‘synergistic risks’ is unclear and little is known about the determinants of such knowledge. This is largely because epistemological progress concerning this topic has been frustrated by a reliance on metrics that have latterly been judged to be of questionable validity. To address this issue, this paper presents two studies that assess an alternative approach (i.e., risk model judgements) which requires respondents to judge the risk for a factor combination relative to, rather than in isolation from, the risk attributable to each constituent factor. Results from both studies indicate that risk model judgements overcome the drawbacks of traditional metrics. More importantly, the results provide epistemological insights into what can determine whether an individual understands that a factor combination presents a synergistic risk; these determinants include experiential and intuitive insights into the effects of combining specific risk factors, domain‐specific judgemental experience and exposure to effective learning opportunities. These findings can be utilized in interventions aimed at helping individuals to make better decisions concerning multiple risk factors.

Towards an understanding of adult judgments of synergistic health benefits

“…Moreover, a study by Dawson et al . () indicated that awareness of certain synergistic health risks (e.g., lung cancer from exposure to radon and tobacco) may be a function of intuitively constructed mental models that depict the human body becoming much more vulnerable to harm when exposed to combinations of hazardous substances. Hence, an a priori causal theory of synergistic health benefits could be underpinned by the formation of rudimentary mental models that depict the human body becoming much more resilient to harmful substances and processes when bolstered by the presence of multiple beneficial factors.…”

“…The answer to this question was the dependent variable; choosing less than , equal to, or more than represented subadditive, additive, or synergistic judgments, respectively. This type of categorical response format has previously demonstrated validity and reliability in studies on judgments of synergistic risks (Condit & Shen, ; Dawson et al ., ).…”

“…Consistent with the design of materials employed by Dawson et al . (), participants first read a short two‐sentence paragraph. The first sentence stated that research evidence showed that a specific single factor (e.g., regularly eating a variety of fruits) had a positive influence on health, because it increases the likelihood of not suffering from life‐threatening health problems, such as cancer.…”

“…As a result of this transformation, the ‘benefit judgment’ variable had two categories (‘synergistic’ and ‘non‐synergistic’) and the data met the test assumptions for three‐way analysis. The practice of collapsing categories in this manner is commonly employed hierarchical loglinear analysis (e.g., Dawson et al ., ; Fairclough, Boddy, Hackett, & Stratton, ). To further facilitate the tests, the HI, EL, and numeracy variables were converted to dichotomous categorical variables as described below.…”

“…First, several studies have examined individual's understanding of the concept of synergistic health risks (the risk attributable to the combination is greater than the sum of the risk attributable to each constituent; e.g., Dawson, Johnson, & Luke, ; French, Gayton, Burton, Thorogood, & Marteau, ; Hampson, Andrews, Lee, Lichtenstein, & Barckley, ). These studies have often found relatively low levels of awareness of the synergistic health risks attributable to less ‘ familiar ’ combinations (e.g., drug–drug combinations such as aspirin and clopidogrel), but relatively high levels of awareness of the synergistic risks associated with more ‘ familiar ’ combinations (e.g., alcohol and driving) (Dawson, Johnson, & Luke, , p. 7; Hampson, Andrews, Barckley, Lee, & Lichtenstein, ). This suggests that certain combinations of factors can become familiar, whether through public awareness campaigns or targeted interventions, as being harmful, and individuals often infer that such combinations elicit synergistic effects.…”