Better Negative than Positive? Evidence of a Bias for Negative Information about Possible Health Dangers

Abstract

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.