Recent research indicates that social trust of those who manage a hazard is strongly correlated to judgments about the hazard's risk and benefits. The present study investigates the more specific question of "For which hazards is this?" It was postulated that when an individual lacks knowledge about a hazard, social trust of authorities managing the hazard determines perceived risks and benefits. On the other hand, when an individual has personal knowledge about a hazard and therefore does not need to rely on managing authorities, social trust is unrelated to judged risks and benefits. Participants (N = 91) assessed risks, benefits, and trust in managing authorities and personal knowledge associated with 25 hazardous technologies and activities. As expected, strong correlations between social trust and judged risks and benefits were observed for hazards about which people did not possess much knowledge. No significant correlations between social trust and judged risks and benefits were found for hazards about which people were knowledgeable. Results suggest that the lay public relies on social trust when making judgments of risks and benefits when personal knowledge about a hazard is lacking. Replicating findings of other studies, the present study also found negative correlations between perceived risks and perceived benefits. When social trust was controlled for, correlations between perceived risks and benefits diminished. Implications of the results for risk management are discussed.

It was postulated that shared values determine social trust in institutions and persons related to a technology: One has trust in people holding similar salient values. Furthermore, it was hypothesized that social trust has a positive influence on perceived benefits and a negative impact on perceived risks. Results of a survey of University of Zurich students indicated that the proposed causal model explained perception of pesticides, nuclear power, and artificial sweetener very well. When social trust was controlled, the relation between risks and benefits perceived diminished. Results indicate that social trust is a key predictive factor of the perceived risks and benefits of a technology, and provide support for the salient values similarity theory of social trust.

Do the results of a scientific study influence confidence in the study's validity and the magnitude of change in the resulting perceived danger of the health risk investigated? Findings from the three investigations reported here indicate that scientific results that confirm a danger (negative results) do affect confidence in a study's validity and resulting risk assessments differently than results indicating low risk (positive results). Findings of Study 1 revealed that research results indicating a health risk were more trusted than results indicating little health risk. This effect was independent of the credibility of the information source. Study 2 demonstrated that confidence in research results increased with an increasing indication of health risk. Study 3 showed that people have more confidence in the results of animal tests on a food additive indicating negative human health effects than in animal tests indicating that a food additive is harmless. The findings have important practical implications. The observed asymmetry between positive and negative research results may be one reason that people are afraid of many of the hazards they are faced with in modern society.

It has been argued that news about negative events has a much stronger effect on decreasing social trust than does news about positive events on increasing it. This asymmetry principle of trust was investigated in two surveys that also investigated the perseverance of trust. The possibility that established trust attributions persevere in the face of new information raises questions about the limits of trust asymmetry. The two studies yielded evidence that both type of news (good versus bad) and initial general trust in the nuclear power industry or the food supply industry affected level of trust. Compared to individuals trusting the industry, those distrusting the industry exhibited less trust following both bad and good news events. Study I also found that judged informativeness and judged positiveness of news events were affected by type of news and general trust of the industry. Individuals low in general trust of the nuclear power industry judged both bad news and good news as less positive than did those high in general trust. Those low in general trust judged bad news as more informative than good news and than did those high in general trust. An important implication of the perseverance of trust is to focus attention on including not only the effects of information about specific events and actions, but also on the judgment processes underlying social trust. The Salient Value Similarity model is suggested as one way of accounting for these psychological processes.

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