title: Differential item functioning analysis of the Vanderbilt Expertise Test for cars.
abstract: The Vanderbilt Expertise Test for cars (VETcar) is a test of visual learning for contemporary car models. We used item response theory to assess the VETcar and in particular used differential item functioning (DIF) analysis to ask if the test functions the same way in laboratory versus online settings and for different groups based on age and gender. An exploratory factor analysis found evidence of multidimensionality in the VETcar, although a single dimension was deemed sufficient to capture the recognition ability measured by the test. We selected a unidimensional three-parameter logistic item response model to examine item characteristics and subject abilities. The VETcar had satisfactory internal consistency. A substantial number of items showed DIF at a medium effect size for test setting and for age group, whereas gender DIF was negligible. Because online subjects were on average older than those tested in the lab, we focused on the age groups to conduct a multigroup item response theory analysis. This revealed that most items on the test favored the younger group. DIF could be more the rule than the exception when measuring performance with familiar object categories, therefore posing a challenge for the measurement of either domain-general visual abilities or category-specific knowledge.
authors.forename: Woo-Yeol
authors.initials: WY
authors.lastname: Lee
authors.forename: Sun-Joo
authors.initials: SJ
authors.lastname: Cho
authors.forename: Rankin W
authors.initials: RW
authors.lastname: McGugin
authors.forename: Ana Beth
authors.initials: AB
authors.lastname: Van Gulick
authors.forename: Isabel
authors.initials: I
authors.lastname: Gauthier
mesh_terms: D000328:Adult; D001336:Automobiles; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011594:Psychometrics / Q000379:methods; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult