There have been ambiguous accounts of exploration in children with intellectual disabilities with respect to the course of that exploration, and in particular the relationship between the features of explored objects and exploratory behaviour. It is unclear whether reduced exploratory activity seen with object exploration but not with locomotor activity is autism-specific or if it is also present in children with other disabilities. The purpose of the present study was to compare preschool children with autism with their peers with Down syndrome and typical development in terms of locomotor activity and object exploration and to determine whether the complexity of explored objects affects the course of exploration activity in children with autism. In total there were 27 children in the study. The experimental room was divided into three zones equipped with experimental objects providing visual stimulation of varying levels of complexity. Our results indicate that children with autism and Down syndrome differ from children with typical development in terms of some measures of object exploration (i.e. looking at objects) and time spent in the zone with the most visually complex objects.