During the second and third years of infancy, intellectual development builds upon achievements made in the first year. This period witnesses profound changes in cognitive growth, characterized primarily by:
① Mastery of numerous new voluntary movements, such as independent walking, running, and jumping. Hand coordination becomes significantly more refined—children can use a small spoon to eat by age 2, string beads with their fingers by age 3, and draw circles with a pen.
② Rapid development of spoken language occurs. Children not only understand adult speech but also engage in basic verbal communication with adults. This period is a critical window for learning oral language; neglect during this time often creates gaps that are difficult to bridge later. Vocabulary expands to about 200 words by age 2 and reaches approximately 1,000 words by age 3.
③ With advancing motor and language skills, toddlers initiate rudimentary play activities while gradually developing capacity for basic imitation and self-care tasks. Imitation is innate in children; by age 1+, they learn games through observation. As age and imagination grow, their play becomes increasingly complex.
④ The emergence of self-awareness introduces a degree of spontaneity into cognitive activities. Children begin to recognize themselves as distinct entities, marking the dawn of self-consciousness. The emergence of the personal pronoun "I" signifies a pivotal moment in this self-recognition. Around age 3, children start using "I" to refer to themselves, indicating the development of self-awareness.⑤ They exhibit a desire for independent action and begin to show the simplest forms of imagination. Their memory span lengthens compared to infancy but remains unintentional. Their thinking remains at a rudimentary stage, characterized by intuitive action thinking.
⑥ Perceptual abilities also develop significantly, such as distinguishing several basic colors. Evaluating preschooler intelligence is based on these developmental characteristics, using methods largely similar to those for infants. Key assessment ages are 15 months, 18 months, 2 years, and 3 years.