Between the ages of two to five years and under average conditions, children’s cognitive, social, and emotional worlds are rapidly expanding and changing (1). Their language abilities expand their capacity for imagination and symbolic thinking and for enlarging social relationships. Their changing cognitive capacities expand their ability for problemsolving and learning about the world. They develop the ability to name their own and others’ feelings and to relate behavior to emotional states and expressions. During the preschool period of development, children are even more commonly in broader social worlds, such as child care and early childhood education programs, and may also experience the birth of a new sibling. While pediatricians remain the most likely professional to be consulted by parents when they are concerned about their two- to five-year-old child’s health and development, a number of other professionals are very likely to be involved in a preschooler’s life, including child care and educational professionals. (Throughout this chapter, the use of the word “parent” is inclusive of all adults that assume an important and regular role in providing care to the child.) Also, this developmental period marks the beginning of more common referrals to child psychiatrists. These referrals come from teachers, parents, and pediatricians most commonly for behavioral problems, especially excessive aggression with peers or other adults, separation difficulties when faced with school and child care programs, developmental delays, especially of speech and language, and concerns about social delays, especially as these relate to social disabilities such as autism.

Development of behavior and competencies is a process of change over time as a child’s characteristics reciprocally transact with the immediate caregiving environment and the broader ecological context, as discussed in the previous chapter on infant and toddler development ((2,3,4,5,6); see Chapter 3.1.1). In the preschool years, specific features of these elements that differ from the earlier infancy and toddlerhood period include, for most preschoolers, increasing sophistication and capacity of cognitive, communicative, and social-emotional skills, a longer history of more varied experiences with parents and primary caregivers, and the high likelihood of exposure, often extensive, to nonparental early care and education contexts, perhaps for the first time.

As with infancy and toddlerhood, the diagnostic nosology for specific disorders among preschool children is only beginning to emerge and only a few diagnostic labels, such as autism and the related social disabilities, are commonly used. Furthermore, social-emotional well-being has received lesser emphasis relative to the impact of cognitive and linguistic competencies on later child outcomes. In addition, developmental change in early childhood is rapid, and assessment of normal and problematic behaviors can be challenging. However, there is a growing body of research evidence that social-emotional and behavioral problems in early childhood are real, not transient, and that occurrence and persistence are associated both with cooccurrence of other problems and with family and parenting difficulties (7). From this and other work, there is general consensus that the understanding of a child’s development requires an appreciation of the caregiving contexts which support, protect, and nurture the child during this period of dependence on adults (8).

In this chapter we review several areas relevant to preschool children’s development and those issues about which child psychiatrists may be most often called upon to consult with families and teachers. The basic developmental areas of normative preschool development include a) robust language learning, including the word-learning explosion and use of language to express emotions and convey more complex or hypothetical information; b) emerging thinking and learning capacities, including executive functioning skills as well as the young child’s emerging ability to reflect on his own and others’ mental activities—feelings, dreams, beliefs, and thoughts; c) emerging peer relationships and the capacity for imaginary play (and imaginary friends); and d) normative issues regarding separation and individuation. Consideration is given to each of these areas’ transactions over time with each other, with caregiving, and with the broader environmental context. Understanding these basic developmental areas is key to a child psychiatrist’s ability to consult effectively when parents and teachers bring developmental concerns about a young child.

In terms of specific consultative questions, we cover three areas in brief—fears and apparent anxiety, aggressive behavior, and child psychiatric consultation to preschool settings as examples of the more common reasons for child psychiatric involvement with preschool children. Specific diagnoses including autism, conduct or oppositional difficulties, attentional problems, and assessment for developmental delay are covered elsewhere in this volume.

A word-learning language explosion begins at about 18 months and continues through the preschool years, during which children learn on average about nine words per day. Language acquisition is robust, with children learning vocabulary and
the fundamentals of linguistic semantics by age 4 or 5, even with very little environmental support (as exemplified by deaf children’s early communication even without language input). However, there appears to be a sensitive period for language proficiency. The specific language a child learns and linguistic qualities such as morphology, grammar, phonology, verbal expression of emotions, and conveyance of information about past, present, or hypothetical events are best learned by the preschool period. The difference among children of differing language proficiency levels on these linguistic qualities is not as much whether or not they can use these linguistic skills, but in the frequency and effectiveness with which they use them in their daily lives. The ease at which these skills can be learned begins to decline at about 6 or 7 years of age (9).

As language proficiency is pivotal for subsequent cognitive and social development, especially school readiness and success, the contributors to development of language proficiency are of great interest. There is evidence that the amount of talk caregivers (usually mothers) direct toward their young children is associated with vocabulary growth and preliteracy skills. The amount and richness of the vocabulary children are exposed to, both child- and other-directed, is also related to language development (10). The genetic contribution of parents is of course important, but so is the family’s socioeconomic status, with children of lower income, less educated parents receiving less quantity and quality of linguistic exposure and demonstrating lower levels of language proficiency (9).

Beginning around two years of age, young children start to form more stable concepts of the world around them. They begin to think symbolically—to use one object to stand for others. For example, young children use scribbled drawings to represent houses, people, animals—and to tell stories using these scribbled bits.

Moreover, in the preschool period, there begin to be vast individual differences in children’s executive functioning—a child’s capabilities to self-regulate, sequence, plan, and organize. The development of these executive controls has a global and lasting effect on later competencies, and problems in executive functioning can lead to later school problems. In contrast, there is little individual variation in normally developing preschoolers’ disposition towards a positive motivation. Young children are intrinsically motivated to explore, try, and learn. In the preschool period, this intrinsic motivation is related to self-attributions about their abilities that are indiscriminately positive. Typically developing preschoolers often perceive themselves as being the best at everything, and to be getting better and better everyday. This disposition often declines on school entry, which may be related to improved cognitive abilities of self-appraisal and social comparison, but is also likely associated with a greater exposure to peers and the increased judgment and potential for criticism in formal school environments. Early education, whether formal or informal by parents and caregivers, should have as a goal encouragement of a child’s natural inclination to explore and learn, not only to foster cognitive skills but also a positive motivation toward learning (9).

The preschool period is also marked by the beginnings of concerted attention to a child’s skills and abilities considered basic to school readiness, as well as basic self-care skills. Children acquire skills best when caregivers present them with tasks that are just a bit too difficult to accomplish independently, but are possible with appropriate assistance. This highly effective approach to teaching young children requires a certain degree of sensitivity to the child’s developmental level, often referred to as the child’s “zone of proximal development (11).” In addition to this type of parent–child interaction, parents encourage their child’s preliteracy and premath skills with activities such as reading, quantitative games, and provision of opportunities such as trips to the library. These activities are most influential when undertaken in warm and nurturing routines. Being read to has the most impact when the child is comfortably and regularly cuddled in a parent’s lap for a bedtime story (9).

By the time children are four to five years old, they have acquired the ability to understand that their thoughts, beliefs, and feelings are their own and that others may feel differently, even believe differently from them. Interpreting the behaviors and words of others as being a part of their feelings and thoughts is a major part of being human and getting along in a social world. This capacity is a remarkable developmental achievement covered broadly under the term developing theory of mind—the notion that a part of social development is seeing the world in both physical and nonphysical terms, with the latter being invisible or imagined states of thoughts, feelings, and beliefs. There is a large literature on the emerging theory of mind in young children, especially as a capacity that does not develop fully in autistic children, and several have proposed distinct stages in this developmental progression—from a physical stance (the world is as we see it, and we predict the world based on the laws of nature) to an intentional stance in which we understand and predict the world at the level of mental states—beliefs, feelings, fears, worries. The boy is crying because he misses his grandmother, or the girl is happy because she got the present she was hoping to receive.

Once children begin to see the world through the lens of mental states, their understanding of their own self and others greatly expands. They are capable then, for example, of playful deceit—hiding something in a way that sends another person down the wrong path because they understand that by providing deceptive clues, the other person develops a false belief as to the whereabouts of an object. They become capable of subtle sarcasm, understanding that just by a change in a tone of voice, someone else reads their intent and not just the meaning of their words. However, during the preschool years, these capacities are just emerging and tend to disappear at moments of fatigue or stress. Thus, a clinician working with a four-year-old who has been remarkably clear about his feelings and the feelings of others may be very surprised when a usually competent boy melts in disappointment or anger because he was sure his mother knew exactly what he was thinking about for his birthday. Further, under stress or unusually severe trauma and neglect, it is very difficult for children to fully develop or allow themselves to imagine the intentions of others who may have been hurtful or neglectful and thus, clinicians working with severely disadvantaged populations may see a delay in the appearance of these very important social perspective-taking capacities. Thus, in addition to understanding where their patients are in basic developmental domains such as cognition, language, fine and gross motor, child psychiatrists working with young children need also to evaluate where their preschool patient is in his/her capacity to think about his own feelings and beliefs as well as those of others. This is most evident in their play (see next section) and less often through direct questions of “How do you feel?” or “What do you think?” though they may answer such questions indirectly about characters in a story or in a play sequence of their own.

Play, broadly defined, covers many activities. One is the rough and tumble play of children running, jumping, chasing, and wrestling with one another. This form is universal across most
cultures, and even across different species. Play also includes verbal forms that are uniquely human, in which children play with sounds and words, even inventing their own language and rhymes—and it is this capacity that is most central to a child psychiatrist’s ability to communicate with younger children through the special language of play. Manipulating and exploring toys and other objects is a form of play that gives young children a chance to learn by looking, feeling, tasting, listening—a form of trial and error, hands-on learning.