Supplementary file 1_Unmasking the anti-gender mindset: development and validation of the Gender Ideology Belief Scale.docx

The present research aimed to develop the Gender Ideology Belief Scale (GIBS), a new measure designed to assess negative attitudes toward gender ideology as a coherent ideological construct.</p>Methods<p>Across two studies involving Italian participants (total N = 595), the GIBS was developed through a multi-phase process including literature review, analysis of public anti-gender discourse, item generation, expert evaluation, and psychometric testing.

In Study 1 (N = 332), exploratory factor analysis was used to identify the most suitable items and examine the latent structure of the scale, whereas in Study 2 (N = 263), confirmatory factor analysis was conducted to test the factorial structure and assess reliability, construct validity, and criterion validity.</p>Results<p>The exploratory factor analysis supported a three-factor solution reflecting conspiratorial beliefs, resistance to gender-inclusive education, and adherence to traditional family values.