Updated Illinois rape myth acceptance scale: an item response theory analysis

Many reasons have been proposed to explain why few sexual assaults are reported, including victim blaming attitudes. These attitudes are called Rape Myths and are used to move the blame from the perpetrators to the victim. The uIRMA is the most established rape myth acceptance measure. While the psychometric properties of the uIRMA are excellent, no studies have assessed the latent structure of the scale through Item Response Theory. Furthermore, there is a lack of knowledge on the psychometric properties of the uIRMA with non-binary individuals. Analyses were conducted on a sample of 1636 participants, composed of men, women and non-binary individuals. The uIRMA is discriminating adequately across genders and items. Furthermore, the difficulty level of corresponding items was lower for men than women and non-binary individuals, with men endorsing more Rape Myths at all levels. However, analyses revealed psychometric concerns with the use of the uIRMA among non-binary participants.