Consumers Believe Legal Products Are Less Effective Than Illegal Products
研究发现消费者普遍认为合法产品效果不如非法产品，即使客观效果相同，这种信念源于对政府管控和产品强度的推断，影响消费者选择，对健康和经济有重要启示。
This research examines how consumers judge a product's effectiveness based on its legal status. Across eight preregistered experiments, the authors find that consumers tend to believe legal products are less effective than illegal ones. Even when observing identical, objective product outcomes (e.g., equal weight loss from a drug), consumers perceive reduced product benefits from a product described as legal (vs. illegal). The authors test an account of why this belief occurs. When a product is legal, consumers infer that the government allows broad access to it, which they associate with lower product strength. In contrast, illegal products, which consumers presume are harder to access, are viewed as higher in product strength. This strength inference leads consumers to believe a legal product produces both smaller positive effects (lower efficacy) and smaller negative effects (lower harm) than an illegal product. Supporting this theory, the impact of legality on perceived efficacy is eliminated if legal and illegal products are described as equally accessible or equally strong. The authors further demonstrate that these beliefs influence consumer choice. Given the significant health and economic consequences of illegal product consumption, this research has important implications for consumers, marketers, public health professionals, and policy makers.