Inhibitory control in children with intellectual disabilities with and without autism spectrum disorders in animal size tests

Objectives: Inhibitory control plays an important role in various aspects of child development. The aim of this study was to compare inhibitory control of children with intellectual disabilities (ID) of unknown etiology, children with ID and autism spectrum disorders (ASD), and typically developing (TD) children. Methods: This study examined 41 children in three groups: 11 children with ID of unknown etiology, 9 children with ID and ASD, and 21 TD children who were matched for mental age. Two Stroop-like tasks were administered: the Real Animal Size Test and the Pictorial Animal Size Test. In these tests, participants are presented with pictures of animals (large animals such as an elephant, a giraffe, and a whale vs. small animals such as a frog, a bird, and a squirrel) printed as either big or small images that are mismatched with the animal's real size. Participants must decide the size of the animals (big vs. small) based either on the size in real life or the size of the picture, resisting interference of irrelevant sizes in real life or in a picture. Results: Interference was greater in the Pictorial Animal Size Test for all groups. Interference was greater in children with ID of unknown etiology compared to TD children, whereas interference was comparable between children with ID and ASD and TD children. Conclusion: Results of this study suggest that inhibitory control is unimpaired in children with ID and ASD but impaired in children with ID of unknown etiology, relative to mental-age matched TD children.