One too many? Understanding the influence of risk factor quantity on perceptions of risk

Forming a subjective risk judgment in circumstances that feature multiple risk factors is a common, yet complex task. One would expect variations in the number of risk factors in a given situation to have an important influence on risk judgments, yet the exact nature of this influence remains empirically untested. We conducted three studies to address this issue. In Study 1, we found that, when individuals were confronted with a preset number of risk factors (zero, one, two or three) in the same scenario, their risk judgments were virtually identical for zero, one and two risk factors, yet markedly higher for three risk factors. By contrast, Study 2 showed that when confronted with variations in the number of risk factors (zero, one, two and three) for that same scenario, individual’s risk judgments increased/decreased in relatively even increments concurrent with increases/decreases in the number of risk factors. Study 3 identified that pronounced increases in risk judgments, like those observed in Study 1, may occur when the numbers of factors is ‘high’ relative to the potential victim’s vulnerability to those factors. Our results show that the number of risk factors in given circumstances can have an important influence on risk judgments and that this influence can differ based on the characteristics of the situation. We discuss how these findings provide a better understanding of subjective risk judgments and highlight the importance of those who seek to communicate risk information should be mindful of how data about multiple risk factors could be (mis)interpreted.