Final answer:
John is displaying abstract thinking by contemplating his own thoughts, which is characteristic of the formal operational stage in Piaget's theory of cognitive development.
Step-by-step explanation:
John, an adolescent, who was thinking about how animals think and then contemplating why he was thinking about how animals think, is displaying abstract thinking, which is a characteristic of the formal operational stage of cognitive development according to Jean Piaget's theory.
This stage, which begins around age 11, allows individuals to consider hypothetical situations and concepts that do not have immediate physical representations. John's metacognitive ability to think about his own thoughts is reflective of this advanced level of cognitive development.