whether photographs or toys depict animals or various inanimate categories (Mandler and McDonough, 1998). Indeed, they can make inferences about them (e.g., of references for above: Baillargeon, 1994; Leslie, 1994; Spelke and Van de Walle, 1995).

Toddlers who move on their own are surprisingly sensitive to the characteristics of surfaces. For example, they adjust their gaits when moving up as opposed to down inclined surfaces; they inspect unfamiliar surfaces like ice, waterbeds, nets, etc., and then adjust their ways of moving. Sensing that a surface is not sturdy, they get down and crawl (Gibson, 1969). These capacities of obsrvation and prediction are the foundation of scientific inquiry.

Toddlers and very young children experiment with tools and work to learn about objects in the world. For example, Ann Brown has shown that 2-year-old children learn quickly about the kinds of objects they can use to retrieve something that is out of reach (Gelman and Brown, 1986). Karmiloff-Smith and Inhelder’s (1974) classic experiment in which children are given blocks to stack, some of which are weighted (reported in Chapter 2), is but one of many that reveal how young children persist at a task, trying out different hypotheses, until they reach a solution.

By age 3, children have learned a surprising amount about the differences between animate and inanimate objects. Indeed, evidence is accumulating that they also know that machines constitute a category separate and different from either animals or inanimate objects (Gelman, 1998; Spelke et al., 1983; Keil, 1989, 1994; Wellman and Gelman, 1992). They already know enough to classify and make inferences about photographs of unfamiliar objects. For example, when asked whether an echidna (an “animal” from Australia that looks a lot like a cactus) can move itself up and down a hill, they give the correct affirmative answer. They also provide reasonable explanations, saying, for example, it must have feet, even if these are not visible in the photograph (Massey and Gelman, 1988).

A wide range of studies converge in concluding that preschool children are eager to learn a great deal about the animal world and to work at learning about the differences between the insides and outsides of objects, the different ways things move and change over time, and a variety of cause-and-effect relationships. They are also able to benefit from language and environments



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