Perceived behavioral costs and social norms as distinct barriers to reducing plastic use across different products and contexts

Plastic pollution is an escalating global concern requiring effective consumer engagement to curtail unnecessary plastic consumption. While psychological factors such as perceived behavioral costs and social norms are known to shape pro-environmental behavior, their differential influence across distinct types of daily plastic reduction behavior remains poorly understood, despite plastics becoming deeply embedded across diverse consumption domains. This study addressed this gap by examining plastic reduction behavior among 2,016 Japanese consumers. We introduced the cost-frequency ratio, perceived behavioral costs divided by behavior frequency, as a novel index that captures the tension between psychological burden and behavioral regularity and reflects the degree to which plastic alternatives have penetrated the everyday consumer context. Exploratory factor analysis of this ratio across 20 items identified five behavior types: selective purchase, use of alternatives, avoiding single-use plastics, avoiding packaging, and habitual plastic reduction. One-way ANOVA revealed that habitual reduction was the most frequent and least costly, while selective purchasing was the least practiced and most costly. Multiple regression analysis showed that perceived behavioral costs negatively predicted habitual plastic reduction, descriptive norms predicted habitual reduction, and subjective norms encouraged the remaining behavior types. These findings demonstrate that the cost-frequency ratio offers a novel and informative approach to classifying plastic reduction behaviors and elucidating the behavior-specific influence of psychological factors. Practically, the results suggest that cost-reducing interventions are most effective for high-cost behaviors, while norm-based strategies should be tailored to the type of social influence most salient for each behavior type.