Childhood and Play
CHILDHOOD AND PLAY
A substantial body of literature regarding children and play exists in the fields of child psychology, child psychotherapy, human geography, anthropology, and studies of children's folklore. The research presents a range of benefits for children and their development. Traditional studies have focused on benefits of play to the individual child; more recently, the focus shifted to the positive impact of play on society as a whole. Previous research has indicated not only a strong belief in the value of play for children but also concern about some of the trends identified in the following review. Examples of research topics include restrictions on children's access to their local environments; the loss of free time; children with disabilities or from ethnic minority groups; and shortages of appropriate play provision. In general, researchers have found that children's play influences their development of social competence, language, and cognition, though findings concerning the impact of play on creativity are mixed. Social, linguistic, and cognitive meaning is the significant center of children's play as well as their education.
This summary of research about children and play is categorized in five broad yet interrelated sections: (1) History of children and play. A brief history of children development is introduced; (2) Theories of children and play. The general theories and principles of children and play are summarized; (3) Themes of children's play. An overview of various themes of play (e.g., toys and games) and play settings for children are illustrated; (4) Cognitive development of children and play. The impact of play on children's cognitive development, such as culture, literary, language, and creativity, are outlined; and (5) The commercialization of children's play. This section focuses on the impact of commodified play on children development in which problems are addressed.
History of Children and Play
One of the first Western philosophers to discuss the childhood and play was Heraclitus (c. 535–470 b.c.) of Ephesus. David Miller quotes an aphorism attributed to Heraclitus, "Time is a child playing, moving counters on a game board" (p. 102). In attempting to unravel this bit of wordplay, Miller recalls a story told by Diogenes Laërtius about Heraclitus. When asked to accept a position of responsibility in his city-state's government, Heraclitus replied that it would be better for him to play knucklebones with the children of Ephesus. The context of this story was that Heraclitus considered the act of playing to be more virtuous than the act of governing. Friedrich Nietzsche, who was interested in Heraclitus's enigma, recalled that the followers of Dionysus, active in sixth century b.c. Ephesus, usually pictured their god as a child playing. If Heraclitus's use of the word time meant "eternity," Heraclitus could be viewed as suggesting play should be an ideal for the proper life. As the gods play, so should man. A basic point in Heraclitus's view was that there was no necessary dichotomy between play and the serious aspects of life.
The play movement in North America began in response to child labor and crowded urban conditions. Early efforts at providing play environments for children drew inspiration from examples of Germans, who valued play and had systematized it as a part of their approach to education. Henry Curtis, writing in The Play Movement and Its Significance, outlined five distinct and independent play movements in the United States: (1) Play spaces. Campaigns for play movement sought to provide a place where children could spend their leisure time and be off the street away from the evil influences they might encounter. Play spaces offered constructive leadership of trained directors as well. (2) Play and child development. The second play movement was built on the assumption that play was essential to the development of children and it must be furnished to every child every day. The focus of this type of play program was in the schools. (3) Outdoor play for young children. This phase of the play movement desired an adequate opportunity for outdoor life and play to children below school age. It came through the facilities and yards of houses, in the interior courts of tenements, and by leaving an open park and playground in the center of all congested blocks. (4) Public recreation. The movement for public recreation asserted that the development of recreation would mean the providing of social centers in the schools with public gymnasiums, dance halls, and swimming pools, either there or elsewhere, the municipalizing of the moving picture and the subsidizing of drama and the opera, and the development of parks and amusement resorts. (5) Spirit of play. The fifth element was not a movement for the rebirth of play, but the spirit of play. The essential values in life and the joy of the work have become more important.
Early studies on children and play focused upon playgrounds, which offer a combination of large playthings in one location, usually outdoors. The first American playground, the Boston Sand Garden, was established in 1885. The original purpose was to provide city children a substitute for a natural setting, and climbing apparatuses took the place of trees. The National Recreation Association, founded in 1930, developed guidelines for certain equipment for playgrounds like providing a sand box, swings, a small slide, and a climber, known as the traditional components of playground. To arouse children's interest, a playground emphasizes exploration, investigation, and manipulation, provides opportunities for play and exercise that go beyond gross motor activity, and provides both sun and shade. Playground games provide two avenues for children's development: unstructured and structured learning. Most of the child's development is from unstructured activities that most do not comprehend.
In recent decades, the construction of playgrounds catered to children with a safer and varied play environment. Modern playgrounds provide places for quiet play and social interaction and large areas for motor play. Equipment is safe, reliable, easy to install, and manufactured in an array of colors and shapes. Studies show that children particularly value play structures that have the following characteristics: complexity and variety; mystery and suspense; perceived risk and challenge; linkage and creative opportunities; lookouts and private hideaways; refuges for social and dramatic play; potential for adult interaction. The passage of the Americans with Disabilities Act of 1990 regulated the design of playground games to make facilities accessible to children with disabilities.
In 1990, the United Nations Convention on the Rights of the Children set out fifty-four articles that identify a range of principles and standards for the treatment of children. A number of the convention's articles are specifically relevant to children's experiences in their local environment and their access to play. The United Nation Declaration of the Rights of the Child suggests that children should have the full opportunity for play and recreation. Play opportunities and playthings stimulate children's development—physical, mental, emotional, and social. These implications highlight three main areas that need to be addressed in terms of a child's right to play: (1) The provision of space, which is a basic resource that children need in order to play. It is by this measure to judge how seriously a community is attending to the needs of its children. (2) Consultation with young people: an explicit requirement underpinning the United Nation Convention; however, in order for this to happen, children and young people need help in making their views known and structures need to be put in place to promote their participation in the planning process. (3) Integration of all children—in particular, those with disabilities—is highlighted by "play is the right of all children" (Article 23), which thus requires the provision of play settings and provide "comfortable and equitable opportunities for integration of children with and without disabilities" (Adams and Ingham, p. 38).
Theories of Children and Play
Most of the research about childhood play provides models and conceptualizations on the issue of goodness for play. In recent decades, research shifts from "Is play good for child development?" to "Why is play good for childhood?" A dozen or more separate theories have been proposed to explain what play is good for. Gene Bammel and Lei Lane Burrus-Bammel group the earliest explanations as "biological theories." It includes the pre-exercise theory that play prepares children for adult roles, and the recapitulation theory that children's play represents the inheritance of physical skills we received from our animal ancestors, for example, tree climbing from monkeys. These theories were eventually replaced by a set that Bammel and Burrus-Bammel label "environmental theories." The emphasis is on the role of external causes in shaping the desire to play, rather than on instinctual or biological causes. Two main theories from this set are Clark Hull's stimulus-response hypothesis and Sigmund Freud's psychoanalytic model. Hull believed that children were taught to play through a complex series of rewards given for participation in play: attention, praise, recognition, status, and so on. Freud, on the other hand, felt that children naturally turned to play to relieve emotional problems and to release frustration resulting from pentup, immature sexual urges.
Bammel and Burrus-Bammel categorize a third set of theories about children and play as cognitive theories. The common theme for these theories is that play is seen as a function of information processing. Jean Piaget developed an influential theory of play as a part of this larger model of childhood development. The child begins at birth in the "sensory-motor stage," and then progresses through three other stages of development. Each stage has a distinctive set of play forms that helps the child's cognitive growth. Based on Piaget's theories of cognitive development, children begin to role-play as early as two years of age; they begin to use mental representation of what they have seen and heard to create an all-new experience in their mind. In more literal terms, they imagine what could happen if thoughts were rearranged, and this process can quickly become a game. This mental exploration is essential to life, as it prepares children to think logically and reason through events and emotions. Studies done on the effects of imagination in childhood have produced a belief that fantasy play has a strong role in the development of a child's mind, but on exactly what that role is, psychologists differ. Furthermore, the research findings are often correlational, and psychologists can consider them to be theories only (because of the roles that a multitude of other factors could play); in addition, these findings do not address the potential dangers in role-play, such as fake violence and discrimination.
Play and games have a major role in the main forms of leisure activity during the period from birth to adolescence. Play does not have to be taught or justified during this period of life because it is a self-motivated behavior; one cannot force a child to play. However, for the children, play is often serious business. Children's sociodramatic play, in which their meanings predominate and in which they employ their personal power, serves as a particularly significant force in integrating their development. For example, children feel power when they play. Their sense of personal power grows out of the dynamic cultural context in which they acquire experiences. Ultimately, children feel competent within the "predictable unpredictability" of play.
In his research, Johan Huizinga identified the following characteristics of play: voluntary, steps outside of ordinary life, limited in time and space, not serious but consuming for participants, bounded by rules, and promotes cultural values and as such is an important means of learning for younger children. Children have much to teach adults about play. Tim Hansel refers to young children as midget gurus of play in that gurus teach people profound truth. He has identified that infants and young children can teach us some of the following principles: (1) Total immersion. No matter what children do, they do it completely and do not worry about any inhibitions. They have the ability to let life embrace them. (2) Total concentration. Children concentrate on one thing and one thing only. Watch children and you will notice how free they are from the problems that plagues our society. (3) Ability to bounce back. The spirit of children is indomitable, as they are able to bounce back from failure to try again and again. (4) Total honesty and expression. Children, according to Hansel, have a wonderful sense of spontaneity, and they tend to be completely open and honest with their feelings.
Themes of Children's Play
Children's play themes grow out of their experiences. Before the growth of television and film culture, children already imitated the behavior of teenagers. For example, children act out adolescent or adult sexual styles or behaviors. Street games, such as stickball and handball, provide an opportunity for children to play with adolescents. Gender themes are always popular for children's play. Beginning early, girls' and boys' play interests and toy choices tend to be gender-oriented. Most girls engage in more sedentary, small-muscle activities, homemaking and fashion themes, while boys engage in more rough-and-tumble, construction, and outdoor-activity themes. Preschool children often play with toilet talk as part of their sense of humor and power. Children are naturally curious about their own bodies, other people, and the world. Their curiosity can be playful, spontaneous, occasional, and voluntary. The sexual exploration differs from anxiety-based, obsessive, or aggressive behavior that involves contextually or personally inappropriate sexual behavior.
Another phenomenon suggests that children's play encompasses various themes—for example, games end with a single winner. In games of two or more children, there are necessarily several (or many) losers, and for the victor, winning itself is the reward. In team-based games, team members who lose together may feel some compensation in the experience of collective effort and camaraderie. Therefore, an emphasis on the fun of playing the game, the exercise of improved skills in completing increasingly difficult games, and the celebration of completion might provide children with some balance when they lose a game. Some researchers recommend that non-competitive games provide one way to reduce or eliminate teasing and bullying. In addition, many commercial games offer more variables than children may be able to juggle. A child will quite probably approach a game much in the same manner that they approach life: willingness to compete or standout, willing to take a risk to win or lose, desires to be in control, refusal to engage in the game, demonstration of foresight and planning, responses to loss or victory. Games can either be a simple way to break the ice, make introductions, or serve as a tool to gain some limited insight into the thoughts and feelings of the child.
Discussion revolving the impacts of toys on children's play is common. Toys inspire the imagination and help children learn new skills. As children express their thoughts and feelings through play, toys assist in the process. When organizing play situations, an objective basis for the selection of toys and materials is important. Items must be intentionally selected rather than just accumulated. The list of toys that have been found most likely to generate interaction and conversation are dishes, blocks, dolls and dollhouses, puppets, wagons, telephones, blocks, colored cubes, balls, crayons, and clay or play dough. Other items commonly found in therapeutic playrooms include cars, trains, balls, paper and scissors, baby bottles, chalkboards and chalk, playing cards and games, and a sink or tub for water play. The rationale for selecting these toys is that they allow, in their own way, the child to create or reconstruct reality from their own perspective. Another suggestion is to include props that specifically pertain to the situation with which the child is currently dealing. For example, if the child were facing an illness, he or she would include a doctor kit in the playroom.
Children who have access to a wide variety of playthings designed for both sexes appear to have the advantage over those whose choices are restricted. Although research suggests that boys tend to play more aggressively with dolls than girls do, dolls provide better outlets for working through problems than do trucks or cars. Michael Ellis, in his book Why People Play, suggested that children have access to toys that enhance the development of a wide variety of skills: imagination, cooperation, turn taking, organizing, physical coordination, and spatial relationships. Well-designed playthings provoke exploration, investigation, manipulation, and contemplation. If an object is sufficiently complex and responsive, the child will investigate its physical properties and seek answers to questions that arise during the investigation, thus developing problem-solving skills. With due consideration for issues of safety, children should be allowed to use toys as they wish, not necessarily as a parent, teacher, or manufacturer thinks they should be used. Studies suggest that using toys may help reduce differences in verbal and other skills between children from middle-income and low-income families.
On the other hand, Gary Cross, in his book Kids' Stuff: Toys and the Changing World of American Childhood, relates a joyless world of useless plastic objects and manipulative advertising aimed at children. It begins with a discussion of how the concept of toys has changed since the nineteenth century, positing that toys are a prime example of a consumer economy run amok. What started out as the manufacture of toys meant to function as educational tools (e.g., building blocks, Legos, etc.) has metamorphosed into Barbies, Power Ranger action figures, and the latest knockoffs from Disney-animated films. The worst thing is that parents have virtually been removed from the equation as toy manufacturers first decide what kind of toys to make and then market them directly to children via Saturday-morning cartoons and the backs of cereal boxes. The world of childhood was controlled by the manufactured fantasies that fuel it. Miriam Formanek-Brunell's Made to Play House: Dolls and the Commercialization of American Girlhood, 1830–1930, addresses a significant issue in the history of childhood through the examination of the links between material objects designed for children, the societal construction of childhood, and children's participation as agents of their own socialization. It explores the dynamic interaction between patterns of production and consumption in the emerging twentieth-century consumer culture, and it proposes that the history of dolls in America (their creation, marketing, and use) documents the struggle of women and girls to gain cultural control of representations of their gender identity. Another book, Purchasing Power: Black Kids and American Consumer Culture, by Elizabeth Chin, studies a group of young African American children in Newhallville, Connecticut, in order to develop and explain a new brand of consumer culture that many previous anthropologists fail to recognize. Chin's research contradicts the stereotypical images in society and those portrayed by the media of African American children. She defines a new image of African American children's culture that goes against commodity fetishism and the need for brand-name goods. She discovers one that deals with the harsh world of being poor and black, where opportunity and survival are major factors of consumer culture. Chin demonstrates the complexity of this issue by displaying how play is woven in with and affected by society. In this way, children's play, as part of consumerism, relates to social injustices, race relations, class diversity, gender differences, cultural baggage, and social relationships.
Cognitive Development of Children and Play
The cultural context of children's play varies depending on the perspectives of play expressed by different scholars. Some investigators generally contend that what may be play in one time and place may be ritualistic or religious, frivolous, or technical behavior elsewhere. The cultural context also determines who may, or is likely to, engage in various kinds of play. The culture teaches what to expect and how to categorize reality and pretend play. Gregory Bateson identifies the concept of a play frame that functions as a territory or context for play. He suggests that children demonstrate by their verbal or nonverbal behavior that they are able to categorize play and not-play as they enter into and step outside the framework of play situations. By planning their parts and actions together, children communicate about their communication (metacommunication). The process of metacommunication takes place outside the play frame. In this way, play is progress in the child's "evolution of communication" and "metacommunication" (Bateson, pp. 121, 125). The metacommunication that takes place in social play makes it possible for children to pretend together because without this type of communication, they would be playing by themselves. When children use an object to bridge the gap between real and make believe, such as using a block as a telephone, or when they interact with others to define a play territory together, they are engaging in symbolic representation, a process that seems to advance youngsters' development. Therefore, play serves as a kind of lymphatic function in childhood education.
Play formats include solitary or social play with objects and others. Sociodramatic play is a particularly powerful form in which children use both imagery and communication about their imagery in seamless ways. Although their imagery grows out of particular personal and cultural contexts, their capacity to engage in metacommunication seems to exist across cultures. Children move comfortably inside and outside the play framework.
Children who play with one another learn that others have views that may differ from their own. They also learn that others have feelings that are similar to their own. They are "decentering" from themselves (Fromberg, p. 26). Therefore, in their social interaction, they are building their "theory of mind," the sense that others have their own ideas and feelings. This insight constitutes an influential aspect of multicultural education. Children's play with others as well as with objects influences their cognitive development. In both cases, the key to competence is flexibility in dealing with ongoing object construction or social construction. Developmental progress can take place more easily when a child uses alternative approaches and perspectives. Further, when children play with others, they get opportunities to expand their knowledge as well as refine their language skills. During play, children engage in activities that expand their imaginations. They work together on problems, create their own games, and take on different roles.
When literacy is included in these types of play, there is no limit to what children can learn. Children who play together in a literate environment are frequently seen to put together the "pieces" of their individual mental work and building up their knowledge in the discourse process. They help each other in figuring out what words, signs, and symbols signify. Children share with one another all the information they know, and together, by brainstorming, they are able to reach a conclusion as to what the sign or symbol may represent or what the word means. Allowing children to play together helps them to take the risks that are involved in thinking aloud. The thinking and sharing atmosphere make it easy for children to sort out their knowledge and bring their implicit understandings to a conscious level. Children engage in more literacy activities and increase their literacy skills when play-area props include literacy materials such as writing tools, signs, posters, banners, books, labels, receipt and appointment books, price lists, and magazines. Other research showed children using more varied and extensive language when play props suggested varied themes. As a haven for controlled risk taking and an attempt to see what is possible, play is a creative process. Researchers have found a relationship between direct tutoring and encouragement to use thematic play with children's later creative use of unstructured props. Greta Fein saw "pretense as an orientation in which the immediate environment is deliberately treated in a divergent manner" (p. 21). However, there is ongoing debate about these findings concerning the connection between play and children's creativity. Some researchers have questioned the impartiality of particular researchers, their definition of children's behavior as play, and the validity of research procedures.
The Commercialization of Children's Play
There is an increasing worry that children have become sedentary and have solitary lifestyles. A number of studies from the field of urban studies raise concerns that children have been conceptualized as problems and the result has been their marginalization and increasing exclusion from a hostile urban environment. What some researchers have termed commercialization of play space and the "commodification" of childhood includes, among other things, issues about access and about whether certain forms of play provision can actually sustain exclusion. Interest in the growing commercialization of play provision and in the considerable expansion of out-of-school provision, is evident in a number of areas of the literature. Both developments have implications for children's opportunities for free play—in particular, because such provision usually involves parental choice and often has a cost implication that also requires adult agreement. According to John McKendrick, Michael Bradford, and Anna Fielder, the growth of commercial playgrounds is adult-led and can be attributed to the conjunction of a number of discrete trends that rendered their development viable. These include the proliferation of the service and leisure industries, the availability of land and buildings, and the growing recognition of children as consumers.
The lives of children today are much more structured and supervised, with limited opportunities for free play. Parents are paranoid of their children being abducted, kidnapped, or physically harmed in the outdoors and public places. In turn, the children's physical boundaries have been limited. A number of factors have led to this: parents are afraid for their children's safety when they leave the house alone; many children are no longer free to roam their neighborhoods or even their own yards unless accompanied by adults; some working families can't supervise their children after school, giving rise to latchkey children who stay indoors or attend supervised after-school activities; children's lives have become scheduled by adults, who hold the biased belief that this sport or that lesson will make their children more successful as adults. There are also concerns that within the education system, children are under mounting pressure to achieve success in academics. As a result, the opportunities for free play are being increasingly squeezed out or downgraded in learning value. These phenomena suggest a greater control over children's play activities, driven in part by parents' concerns for safety and concerns about the quality of facilities within the local environment.
Another important influence has been a major change in family life that has taken place over the last few decades, which is leisure as a shared family experience. For example, commercial playgrounds, largely based on pay-for-play, raise the possibility that they will not cater to all groups and could therefore potentially be a cause of exclusion. With regard to the trend toward increasingly supervised leisure and recreational activities in out-of-school hours, a number of studies have highlighted the significant expansion of out-of-school clubs, often to provide child care for working parents or to promote study support.
Therefore, the definitions used for children's play are often imprecise and the boundaries between play, game, sport, learning, and education remain poorly defined. Furthermore, there are unresolved disputes as to whether positive outcomes are necessarily related to play-specific processes or more generic processes, such as social interaction.
The commodification of play involves looking at play as a something to be bought and sold. With this in mind, people have worked to develop games and toys around this idea of play as a commodity. For example, online team play can be viewed as a form of commercialization in which children can communicate with one another through their PlayStations, or through media such as message boards and text messaging. While the manufacturers have created many commercial toys that can interact with children, the video game technology made a huge contribution to children's play in recent years. Technology and the video game industry continue to change and improve, which will make games better and more interactive for children. The better the gaming experience, the more children will play and talk about the game.
Due to all of the new technologies being designed and put into production, there are many different outcomes for play. Young children play at being television superheroes and superheroines, enact teenage behavior, and explore violent themes or behavior. Across the industry, children are generally the first to decide what is fashionable, and consumer electronics and software are no different. Children influence functionality as well as style and have already driven trends like online messaging and gaming in various fields. On the other hand, it is important to remember that technological advancements can produce both threats and potentialities for children's development. The findings by Stephen Kline, Nick Dyer-Witherford, and Greig Peuter, show that children's play, such as video games are worthy of serious study because they represent the "ideal-type" postmodern commodity. So whereas the automobile is closely associated with the "industrial capitalism" of the Fordist era, the video game embodies the "information capitalism" of today's "perpetual innovation" society for children's development.
In sum, play is to a child what work is to an adult: it depends upon what they do. Children learn about their world and the things in it through play, which allows children the chance to explore their environment, to learn how it works and how they relate to it. This summary presents that a child can express feelings and emotions through various types of play activities far earlier than they can express them in words. Play serves the outlet through which children convey emotions that they are either unwilling to share verbally or do not have the sufficient vocabulary to express. Through play, professionals as well as the general public can identify children's feelings, confusions, and questions. The technology advancement has influenced the types of play for children, in which play has become a commodity. Children interact through online video games and create online messaging. A new form of play is emerged and evolved to be an integral part of children's development. Therefore, play provides a wide variety of choices for children, who can be anyone, at any place, at anytime.
See also: Children's Reading, Commercialization of Children's Play; Computer/Video Games; Playgrounds; Teenage Leisure Trends
Adams, Eileen, and Sue Ingham. Changing Places—Children's Participation in Environmental Planning. London: Children's Society, 1998.
Bammel, Gene, and Lei Lane Burrus-Bammel. Leisure and Human Behavior. Dubuque, Iowa: William C. Brown, 1992.
Bateson, Gregory. "A Theory of Play and Fantasy." In Play: Its Role in Development and Evolution. Edited by Jerome Bruner, Alison Jolly, and Kathy Sylva. New York: Basic Books, 1976.
Chin, Elizabeth. Purchasing Power: Black Kids and American Consumer Culture. Minneapolis: University of Minnesota Press, 2001.
Cross, Gary. Kids' Stuff: Toys and the Changing World of American Childhood. Cambridge, Mass.: Harvard University Press, 1997.
Curtis, Henry. The Play Movement and Its Significance. New York: Macmillan, 1917.
Ellis, Michael. Why People Play. Upper Saddle River, N.J.: Prentice-Hall, 1973.
Fein, Greta. "The Affective Psychology of Play". In Play Interactions: The Role of Toys and Parental Involvement in Children's Development. Edited by Catherine Brown and Allen Gottfried. Skillman, N.J.: Johnson and Johnson, 1985.
Formanek-Brunell, Miriam. Made to Play House: Dolls and the Commercialization of American Girlhood, 1830–1930. New Haven, Conn.: Yale University Press, 1993.
Freud, Sigmund. "Beyond the Pleasure Principle." In The Standard Edition of the Complete Psychological Works of S. Freud, 1920–1922. Volume 18. Edited and translated by James Strachey. London: Hogarth and the Institute of Psychoanalysis, 1955.
Fromberg, Doris Pronin. Play and Meaning in Early Childhood Education. Boston: Allyn and Bacon, 2002.
Hansel, Tim. When I Relax I Feel Guilty. Elgin, Ill.: David Cook Publishing, 1979.
Huizinga, Johan. Homo Ludens—A Study of the Play Element in Culture. Boston: Beacon Press, 1962.
Hull, Clark. "S-R Analysis of Cognitive Processes." In Mechanisms of Adaptive Behavior: Clark Hull's Theoretical Papers. Edited by Abram Amsel and Michael Rashotte. New York: Columbia University Press, 1984.
Kline, Stephen, Nick Dyer-Witherford, and Greig Peuter. Digital Play: The Interaction of Technology, Culture, and Marketing. Toronto: McGill-Queens University Press, 2003.
McKendrick, John, Michael Bradford, and Anna Fielder. "Kid Customer? Commercialization of Playspace and the Commodification of Childhood." Childhood 7 (2000): 295–314.
Miller, David. Gods and Games: Toward a Theology of Play. New York: Harper Colophon, 1973.
Morris, Charles G., and Albert A. Maisto. Understanding Psychology. Upper Saddle River, N.J.: Prentice-Hall, 2001.
Nietzsche, Friedrich. "Ecce Homo." In The Philosophy of Nietzsche. Volume 10. Edited by Geoffrey Clive. New York: New American Library, 1965.
Piaget, Jean. Play, Dreams, and Imitation in Childhood. Translated by C. Gattegno and F. N. Hodgson. New York: Norton, 1962.
Smith, Peter. Play in Animals and Humans. New York: Basil Blackwell, 1984.
——. "Play and Associative Fluency: Experimenter Effect May Be Responsible for Previous Positive Findings." Developmental Psychology 23, no. 1 (1987): 49–53.
Philip F. Xie