Summary

1. Piaget realized that very young infants are active learners who seek to understand their complex observations and experiences. The six stages of sensorimotor intelligence involve early adaptation to experience.
2. Sensorimotor intelligence begins with reflexes and ends with mental combinations. The six stages occur in pairs, with each pair characterized by a circular reaction; infants first react to their own bodies (primary), then respond to other people and things (secondary), and finally, in the stage of tertiary circular reactions, infants become more goal-oriented, creative, and experimental as “little scientists.”
3. Infants gradually develop an understanding of objects. As shown in Piaget’s classic experiments, infants understand object permanence and begin to search for hidden objects at about 8 months. Newer research, using brain scans and other new methods, finds that Piaget underestimated infant cognition, including his conclusions about when infants understand object permanence and when they defer imitation.

4. Another approach to understanding infant cognition involves information-processing theory, which looks at each step of the thinking process, from input to output. The perceptions of a young infant are attuned to the particular affordances, or opportunities for action, that are present in the infant’s world.
5. Objects, creatures and especially people that move are particularly interesting to infants, because they afford many possibilities for interaction and perception. Early affordances are evidence of early cognition.
6. Infant memory is fragile but not completely absent. Reminder sessions help trigger memories, and young brains learn motor sequences and respond to repeated emotions (their own and those of other people) long before they can remember with words. Memory is multifaceted; explicit memories are rare in infancy.

7. Language learning, which distinguishes the human species from other animals, may be the most impressive cognitive accomplishment of infants. The universal sequence of early language development is well known; there are alternative explanations for how early language is learned.
8. Eager attempts to communicate are apparent in the first weeks and months. Infants babble at about 6 months, understand words and gestures by 10 months, and speak their first words at about 1 year. Deaf infants make their first signs before a year.
9. Vocabulary builds slowly until the infant knows approximately 50 words. Then the naming explosion begins. Toward the end of the second year, toddlers put words together in short sentences. The tone of holophrases is evidence of grammar, but putting two or three words together in the proper sequence is proof.
10. Various theories explain how infants learn language as quickly as they do. The three main theories emphasize different aspects of early language learning: that infants must be taught, that their social impulses foster language learning, and that their brains are genetically attuned to language as soon as the requisite maturation has occurred.
11. Each theory of language learning is confirmed by some research. The challenge for developmental scientists has been to formulate a hybrid theory that uses all the insights and research on early language learning. The challenge for caregivers is to respond to the infant’s early attempts to communicate, expecting neither too much nor too little.