Assessment of physical self-concept in adolescents with intellectual disability: content and factor validity of the very Short Form of the Physical Self-Inventory.

The purpose of this study was to test the factor validity and reliability of the Very Short Form of the Physical Self-Inventory- (PSI-VSF) within a sample of adolescents with mild to moderate Intellectual Disability (ID). A total of 362 ID adolescents were involved in two studies. In Study 1, the content and format scale response of the PSI-VSF were adapted for adolescents with ID. This instrument was thus renamed PSI-VSF-ID and two versions with two alternative responses scales format, were developed: Likert and graphical. In Study 2, results provided support for: (1) the factorial validity and reliability; and (2) factorial invariance across gender, age, type of school placement and ID level of the PSI-VSF-ID associated with a graphical response scale format.