Expert relevance and the use of context-driven heuristic processes in risk perception

The effectiveness of a medical treatment should not predict its risk (highly effective treatments can be either safe or risky), however, people's use of heuristic shortcuts may lead them to judge a link between effectiveness and risk, typically a negative correlation. A particular concern is that experts might use such a strategy and that this is unlikely to provide an accurate judgement. This large-scale field-based experiment compares expert-relevant and non-expert-relevant contexts, for both expert and public judgements of risk and effectiveness in the context of blood transfusion medicine. Postal questionnaires were distributed to anaesthetists (experts, N = 123) and a general public (non-expert) comparison group (N = 1153); half of the participants were cued with accompanying general information about genetically-modified (GM) biotechnology and half received specific information about blood product technologies. The blood-focussed information served to emphasise the medical relevance of the questionnaire to the expert group. Regression analyses showed that generally perceived effectiveness predicted perceived risk for both experts and non-experts, which suggests heuristic processing. However, although experts appeared to engage in heuristic processing for risk perceptions in certain circumstances, this processing is strongly affected by context. Experts who received the medically relevant context rated perceptions of effectiveness independently of perceptions of risk, unlike those who received the GM context. This indicates a reduced reliance on a low-effort heuristic for experts given an expertise-relevant context. The results are considered in light of dual-process (rational-associative) accounts of reasoning.