Shown 8 dogs and 3 cats, a 4-year-old says there are more dogs than animals. She lacks:

1. The girl knows dogs and cats are both animals. 2. Yet she compares dogs with animals as if they were separate groups. 3. Understanding that one class (animals) contains its subclasses (dogs, cats) is **class inclusion**. 4. She cannot hold the subclass and the whole class in mind at once, so she says more dogs. **Why not the others:** Conservation is about amounts staying the same after a change of shape; object permanence was gained in infancy. _Source: Wikipedia, "Piaget's theory of cognitive development", section "Intuitive thought substage" (revision 1379038101)_