The answer is "sensorimotor stage (of cognitive development) ".
The sensorimotor stage is the most earliest in Piaget's theory of cognitive development. He depicted this period as a period of huge development and change.
Amid this underlying period of development, children use aptitudes and capacities they were conceived with, (for example, looking, sucking, getting a handle on, and tuning in) to take in more about the earth. As such, they encounter the world and gain learning through their faculties and engine developments.