As children move from the sensorimotor to the preoperational stage, which spans the years 2 to 7, the most obvious change is an extraordinary increase in representational, or symbolic, activity. Recall that infants and toddlers have considerable ability to mentally repre-sent their world. In early childhood, this capacity blossoms.
Later, children combine schemes with those of peers in sociodramatic play, the make- believe with others that is under way by the end of the second year and that increases rapidly in complexity during early child-hood ( Kavanaugh, 2006a). Already, Sammy and his classmates can create and coordinate several roles in an elaborate plot. By the end of the preschool years, children have a sophis-ticated understanding of role relationships and story lines.
dual representation— viewing a symbolic object as both an object in its own right and a symbol. In
For Piaget, the most fundamental deficiency of preoperational thinking is egocentrism— failure to distinguish the symbolic viewpoints of others from one's own. He believed that when children first mentally represent the world, they tend to focus on their own viewpoint and assume that others perceive, think, and feel the same way they do.
Piaget's most convincing demonstration of egocentrism in-volves his three- mountains problem, described in Figure 9.1. He also regarded egocentrism as responsible for preoperational chil-dren's animistic thinking— the belief that inanimate objects have lifelike qualities, such as thoughts, wishes, feelings, and intentions ( Piaget, 1926/ 1930). Recall Sammy's insistence that someone must have turned on the thunder. According to Piaget, because young children egocentrically assign human purposes to physical events, magical thinking is common during the preschool years.
Piaget's famous conservation tasks reveal several deficiencies of preoperational thinking. Conservation refers to the idea that certain physical character-istics of objects remain the same, even when their outward appearance changes. At snack time, Sammy and Priti had identi-cal boxes of raisins, but when Priti spread her raisins out on the table, Sammy was convinced that she had more.
The inability to conserve highlights several related aspects of preoperational children's thinking. First, their understanding is centered, or characterized by centration. They focus on one aspect of a situation, neglecting other important features. In conservation of liquid, the child centers on the height of the water, failing to realize that changes in width compensate for the changes in height. Second, children are easily distracted by the perceptual appearance of objects. Third, children treat the initial and final states of the water as unrelated events, ignoring the dynamic transformation ( pouring of water) between them.
The most important illogical feature of preoperational thought is its irreversibility— an inability to mentally go through a series of steps in a problem and then reverse direc-tion, returning to the starting point. Reversibility is part of every logical operation. After Priti spills her raisins, Sammy cannot reverse by thinking, " I know Priti doesn't have more raisins than I do. If we put them back in that little box, her raisins and mine would look just the same."
Preopera-tional children have difficulty with hierarchical classification— the organization of objects into classes and subclasses on the basis of similarities and differences. Piaget's famous class inclu-sion problem, illustrated in Figure 9.3, demonstrates this limi-tation. Preoperational children center on the overriding feature, red. They do not think reversibly, moving from the whole class ( flowers) to the parts ( red and blue) and back again.
Over the past three decades, almost all studies have supported Vygotsky's perspective ( Berk & Harris, 2003; Winsler, 2009). As a result, children's self-directed speech is now called private speech instead of egocentric speech. Research shows that children use more of it when tasks are appropriately challenging— neither too easy nor too hard but within their zone of proximal development, or range of mastery ( see page 224 in Chapter 6). For example, Figure 9.5 shows how 5- and 6- year- olds' private speech increased as re-searchers made a problem- solving task moderately difficult, then decreased as the task became very difficult ( Fernyhough & Fradley, 2005).
To promote cognitive development, social inter-action must have two vital features. The first is intersubjectivity, the process by which two par-ticipants who begin a task with different understandings arrive at a shared understanding ( Newson & Newson, 1975). Intersubjectivity creates a common ground for communication, as each partner adjusts to the other's perspective. Adults try to promote it when they translate their own insights in ways that are within the child's grasp. As the child stretches to understand the adult, she is drawn into a more mature approach to the situation ( Rogoff, 1998).
A second important feature of social experience is scaffolding— adjusting the support offered during a teaching session to fit the child's current level of performance. When the child has little notion of how to proceed, the adult uses direct instruction, breaking the task into manageable units, sug-gesting strategies, and offering rationales for using them. As the child's competence increases, effective scaffolders— like Sammy's mother— gradually and sensitively withdraw sup-port, turning over responsibility to the child. Then children take the language of these dialogues, make it part of their pri-vate speech, and use this speech to organize their independent efforts.
Scaffolding captures the form of teaching interaction that occurs as children work on school or school- like tasks, such as puzzles, model building, picture matching, and ( later) academic assignments. It may not apply to other contexts that are equally vital for cognitive development— for example, play or everyday activities, during which adults usually support children's efforts without deliberately teaching. To encompass children's diverse opportunities to learn through involvement with others, Barbara Rogoff ( 1998, 2003) suggests the term guided participation, a broader concept than scaffolding. It refers to shared endeavors between more expert and less expert participants, without specifying the precise features of communication. Consequently, it allows for variations across situations and cultures.
During early childhood, children also become better at planning— thinking out a sequence of acts ahead of time and allocating attention accordingly to reach a goal. As long as tasks are familiar and not too complex, preschoolers can generate and follow a plan. For example, 4- year- olds can search for a lost object in a play area systematically if possible loca-tions are few ( McColgan & McCormack, 2008). But when asked to compare detailed pictures, preschoolers fail to search thoroughly. And on tasks with several steps, they often fail to decide what to do first and what to do next in an orderly fashion ( Baughman & Cooper, 2006; Friedman & Scholnick, 1997; Kaller et al., 2008). They seem to have difficulty postponing action in favor of mapping out a sequence of moves and evaluating the consequences of each— procedures that require inhibition and increased working- memory capacity in addition to planning skill.
But even preschoolers with good language skills recall poorly because they are not skilled at using memory strategies, deliberate mental activities that improve our chances of remembering. For example, to retain information, you may rehearse, repeating the items over and over, or organize, intentionally grouping items that are alike so that you can easily retrieve them by thinking of their similar characteristics.
The difference between your recall of listlike information and your memory for everyday experiences— what researchers call episodic memory. In remembering lists, you recall isolated bits, reproducing them exactly as you originally learned them. In remembering everyday experiences, you recall complex, meaningful information. Between 3 and 6 years, children improve sharply in memory for relations among stimuli. For example, in a set of photos, they remember not just the animals they saw but the contexts in which they saw them— a bear emerging from a tunnel, a zebra tied to a tree on a city street ( Sluzenski, Newcombe, & Kovacs, 2006). The capacity to bind together stimuli when encoding and retrieving them supports the development of an increas-ingly rich event memory during early childhood.
Like adults, preschoolers remember familiar, repeated events— what you do when you go to child care or have dinner— in terms of scripts, general descriptions of what occurs and when it occurs in a par-ticular situation. Young children's scripts begin as a structure of main acts. For example, when asked to tell what happens at a restaurant, a 3- year- old might say, " You go in, get the food, eat, and then pay." Although children's first scripts con-tain only a few acts, as long as events in a situation take place in logical order, they are almost always recalled in correct sequence ( Bauer, 2002, 2006). With age, scripts become more spontaneous and elaborate, as in this 5- year- old's account of going to a restaurant: " You go in. You can sit in a booth or at a table. Then you tell the waitress what you want. You eat. If you want dessert, you can have some. Then you pay and go home" ( Hudson, Fivush, & Kuebli, 1992). Scripts help children organize, interpret,
Limitations of Preoperational Thought
Limitations of Preoperational Thought Aside from gains in representation, Piaget described preschoolers in terms of what they cannot understand ( Beilin, 1992). As the term preoperational suggests, he compared them to older, more competent children who have reached the concrete operational stage. According to Piaget, young children are not capable of operations— mental actions that obey logical rules. Rather, their thinking is rigid, limited to one aspect of a situation at a time, and strongly influ-enced by the way things appear at the moment.
According to overlapping-waves theory, when given challenging problems, children try out various strategies and observe which work best, which work less well, and which are ineffective. Gradually, they select strategies on the basis of two criteria: accuracy and speed— for basic addition, the min strategy. As children home in on effective strategies for solving the problems at hand, correct solutions become more strongly associated with problems, and children display the most efficient strat-egy— automatic retrieval of the answer.
Theory of mind
As representation of the world, memory, and problem solving improve, children start to reflect on their own thought processes. They begin to construct a theory of mind, or coherent set of ideas about mental activities. This understanding is also called metacognition, or " thinking about thought" ( the prefix meta- means " beyond" or " higher"). As adults, we have a complex appreci-ation of our inner mental worlds, which we use to interpret our own and others' behavior and to improve our performance on various tasks. How early are children aware of their mental lives, and how complete and accurate is their knowledge?
In child- centered programs, teachers provide activities from which children select, and much learning takes place through play. In contrast, in academic programs, teachers structure children's learning, teaching let-ters, numbers, colors, shapes, and other academic skills through formal lessons, often using repetition and drill.
Project Head Start
The most extensive of these federal programs, Project Head Start, began in 1965. A typical Head Start center provides children with a year or two of preschool, along with nutritional and health services. Parent involvement is central to the Head Start philosophy. Parents serve on policy councils, contribute to program planning, work directly with children in classrooms, attend special programs on parenting and child development, and receive services directed at their own emotional, social, and vocational needs. Currently, more than 18,000 U. S. Head Start centers serve about 908,000 children ( Head Start Bureau, 2008).
At age 2, Sammy had a spoken vocabulary of 200 words. By age 6, he will have acquired around 10,000 words ( Bloom, 1998). To accomplish this feat, Sammy will learn about five new words each day. How do children build their vocabularies so quickly? Research shows that they can connect new words with their underlying concepts after only a brief encounter, a process called fast mapping. Even toddlers comprehend new labels remarkably quickly, but they need more repetitions of the word's use across several situations than preschoolers, who process speech-based information faster and are better able to categorize and recall it ( Akhtar & Montague, 1999; Fernald, Perfors, & Marchman, 2006). During the preschool years, children become increasingly adept at fast- mapping two or more new words encountered in the same situation ( Wilkinson, Ross, & Diamond, 2003).
mutual exclusivity bias
How do children discover which concept each word picks out? This process is not yet fully understood. One speculation is that early in vocabulary growth, children adopt a mutual exclusivity bias— the assumption that words refer to entirely separate ( nonoverlapping) categories ( Markman, 1992). Two- year- olds seem to rely on mutual exclusivity when the objects named are perceptually dis-tinct— for example, differ clearly in shape. After hearing the labels for two dis-tinct novel objects ( for example, clip and horn), they assign each word correctly, to the whole object, not just a part of it ( Waxman & Senghas, 1992).
By age 3, preschoolers' memory, categorization, and language skills have expanded, and they assign multiple labels to many objects ( Deák, Yen, & Pettit, 2001). For example, they refer to a sticker of a gray goose as " sticker," " goose," and " gray." In these instances, children often call on other aspects of language. According to one proposal, preschoolers discover many word meanings by observing how words are used in syntax, or the structure of sentences— a hypoth-esis called syntactic bootstrapping ( Gleitman et al., 2005; Naigles & Swenson, 2007). Consider an adult who says, " This is a citron one," while showing the child a yellow car. Two- and 3- year-olds conclude that a new word used as an adjective for a familiar object ( car) refers to a prop-erty of that object ( aprop-ertyofthatobject( Hall & Graham, 1999; Imai & Haryu, 2004). As preschoolers hear the word in various sentence structures (" That lemon is bright citron"), they use syntactic information to refine the word's meaning and generalize it to other categories.
Once children acquire these markers, they sometimes overextend the rules to words that are exceptions, a type of error called overregular-ization. " We each got two foots" and " My toy car breaked" are expressions that appear between ages 2 and 3 and persist into middle childhood ( Maratsos, 2000; Marcus, 1995). Children less often make this error on frequently used irregu-lar verbs, such as the past tense of go ( went) and say ( said), which they hear often enough to learn by rote. For rarely used verbs such as grow and sing, children alternate for months— or even several years— between overregularized forms ( growed, singed) and correct forms, until the irregular form eventually wins out. Since chil-dren do not hear mature speakers use these forms, overregularization provides evidence that children apply grammatical rules creatively.
According to one view, young children rely on semantics, or word meanings, to figure out grammatical rules— an approach called semantic bootstrapping. For example, children might begin by grouping together words with " agent qualities" ( things that cause actions) as subjects and words with " action qualities" as verbs. Then they merge these categories with observations of how words are used in sentences ( Bates & MacWhinney, 1987; Braine, 1994).
Besides acquiring vocabulary and grammar, children must learn to engage in effective and appropriate communication— by taking turns, staying on the same topic, stating their mes-sages clearly, and conforming to cultural rules for social interaction. This practical, social side of language is called pragmatics, and preschoolers make considerable headway in mastering it. As early as age 2, children are skilled conversationalists.
Instead, adults often provide indirect feedback about grammar by using two strategies, often in combination: recasts— restructuring inaccurate speech into correct form, and expansions— elaborating on children's speech, increasing its complexity ( Bohannon & Stanowicz, 1988; Chouinard & Clark, 2003). For example, if a child says," I gotted new red shoes," the parent might respond, " Yes, you got a pair of new red shoes." In one study, after such corrective input, 2- to 4- year- olds often shifted to correct forms— improvements still evident several months later ( Saxton, Backley, & Galloway, 2005). However, the impact of such feedback has been challenged. The techniques are not used in all cultures and, in a few investigations, had no impact on chil-dren's grammar ( Strapp & onchil-dren'sgrammar(Strapp& Federico, 2000; Valian, 1999). Rather than eliminating errors, perhaps expansions and recasts model grammatical alternatives and encourage children to experiment with them.