Final answer:
Critics of Piaget's theory argue that development is more continuous and that children reach cognitive milestones earlier than described by Piaget.
Step-by-step explanation:
One criticism of Piaget's theory of early development is that it suggests development occurs in discrete stages, while contemporary studies suggest that development is more continuous. For example, Courage & Howe (2002) and Siegler (2005, 2006) support a model of development that is more gradual. Another criticism is that Piaget's theory suggests certain cognitive milestones occur at specific ages, but many studies have found that children reach these milestones earlier than Piaget described. For instance, Baillargeon (2004) and de Hevia & Spelke (2010) found that children demonstrate cognitive abilities earlier than Piaget's theory predicts.