This curious, slobbery interaction with the world is what Piaget called the sensorimotor stage – the level of development where all knowledge is based on what you can perceive with your senses.

皮亚杰将这种与世界的好奇、口齿不清的互动称为感觉运动阶段——所有知识都基于你可以用你的感官感知的发展水平。