chapter summary:

To understand their experiences, children must learn that the world includes several types of objects: people, other living things, and inanimate objects. Children also need a basic understanding of causality, space, time, and number, so that they will be able to code their experiences in terms of why, where, when, and how often events occurred.

Understanding Who or What

• Early categories of objects are based in large part on perceptual similarity, especially similarity in the shapes of the objects.
• By age 2 or 3 years, children form category hierarchies: animal/dog/poodle, furniture/chair/La-Z-Boy, and so on.
• From infancy onward, children differentiate people from other animals and inanimate objects. For example, infants smile more at people than at either rabbits or robots.
• By age 4 or 5 years, preschoolers develop a rudimentary but well-organized theory of mind, within which they organize their understanding of people’s behavior. A key assumption of this theory of mind is that desires and beliefs motivate specific actions.
• Understanding that other people will act on their beliefs, even when the beliefs are false, is very difficult for 3-year-olds; many children do not gain this understanding until age 5.
• Animals and plants, especially animals, are of great interest to young children. When animals are present, infants and toddlers pay careful attention to them.
• By age 4 years, children develop an elaborate understanding of living things, including coherent ideas about invisible processes such as growth, inheritance, illness, and healing. Both their natural fascination with living things and the input they receive from the environment contribute to their knowledge about plants and animals.

Understanding Why, Where, When, and How Many

• The development of causal reasoning about physical events begins in infancy. By 6 to 12 months, infants understand the likely consequences of objects colliding. Understanding causal relations among actions helps 1-year-olds remember them.
• By 4 or 5 years, children seem to realize that causes are necessary for events to occur. When no cause is obvious, they search for one. However, many preschoolers believe in magic as well as physical cause–effect relations.
• People, like other animals, are biologically prepared to code space. Early in infancy, they code locations of other objects in relation to their own location and to landmarks. As they gain the ability to move around on their own, children gain a sense of locations relative to the overall environment as well as to their own current location.
• Children who are born blind have surprisingly good representations of space, though some aspects of their spatial processing, especially processing of faces, remain poor even if corrective surgery is performed during infancy.
• Just as infants are born with an ability to code some aspects of space, so they are born with an ability to code some aspects of time. Even 3-month-olds code the order in which events occur. Infants of that age also can use consistent sequences of past events to anticipate future events.
• By age 5 years, children also can reason about time, in the sense of inferring that if two events started at the same time, and one stopped later than the other, the event that stopped later took longer. However, they can do this only when interfering perceptual cues are absent.
• Rudimentary understanding of very small numbers is present from early in infancy. Infants notice numerical differences between small sets of objects and between events that are repeated a different number of times. They also notice differences between larger sets when the numbers of objects or events in the sets differ by large ratios.
• By age 3 years, most children learn to count 10 objects. Their counting seems to reflect understanding of certain principles, such as that each object should be labeled by a single number word. Children’s subsequent rate of learning about numbers reflects their culture’s number system and the degree to which their culture values numerical knowledge.
• From infancy onward, children also possess a general representation of magnitude that extends at least to space, time, and number.