Irrational health beliefs as barriers to health behaviors: development and validation of a brief scale in a Japanese population

Health communication and public health research has shown that providing accurate, evidence-based information does not necessarily lead to appropriate health decisions or behaviors. Cognitive biases and irrational health beliefs may contribute to this gap by shaping how individuals interpret health information. However, practical tools for assessing such beliefs in population-based research remain limited. This study aimed to validate a Japanese version of the Irrational Health Belief Scale (IHBS) and to develop and validate a short form suitable for use in public health research. An online survey was conducted among 408 Japanese adults aged 20 to 69 years. Participants completed a Japanese version of the IHBS, as well as measures of health literacy, health locus of control, and health behaviors. Exploratory factor analysis (EFA) was used to examine the scale structure and to develop a short form based on factor loadings, conceptual coverage, and item distribution. Confirmatory factor analysis (CFA) of the 20-item IHBS was subsequently conducted to evaluate the fit of the proposed unidimensional structure. Internal consistency was assessed using Cronbach’s alpha, and construct and criterion-related validity were examined by exploring the associations with health literacy, health locus of control, and health-related behaviors. EFA indicated a largely unidimensional structure of the Japanese IHBS, and CFA showed a generally acceptable fit for the one-factor model. A 5-item short form of the IHBS was developed. Both the full scale and the short form showed acceptable internal consistency (Cronbach’s alpha = 0.91 and 0.78, respectively), and the two versions were highly correlated ( r = .90). Higher irrational health belief scores were associated with lower health literacy, lower internal health locus of control, higher chance health locus of control, and less favorable health behaviors. Irrational health beliefs appear to be a measurable and potentially modifiable cognitive determinant of health behaviors. The brief scale provides a concise tool for identifying individuals who may be more likely to misinterpret health information and may be useful in studies examining barriers to effective public health communication.