Play (activity) - AbsoluteAstronomy.com

Play is a term employed in ethology

Ethology

Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

Psychology

Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

to describe to a range of voluntary

Free will

"To make my own decisions whether I am successful or not due to uncontrollable forces" -Troy MorrisonA pragmatic definition of free willFree will is the ability of agents to make choices free from certain kinds of constraints. The existence of free will and its exact nature and definition have long...

, intrinsically motivated activities normally associated with pleasure and enjoyment. Play is commonly associated with children, but positive psychology

Positive psychology

Positive psychology is a recent branch of psychology whose purpose was summed up in 1998 by Martin Seligman and Mihaly Csikszentmihalyi: "We believe that a psychology of positive human functioning will arise, which achieves a scientific understanding and effective interventions to build thriving in...

has stressed that play is imperative for all higher-functioning animals, even adult humans.

The rites of play are evident throughout nature and are perceived in people and animals, although generally only in those species possessing highly complex nervous system

Nervous system

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

s such as mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s and bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s. Play is most frequently associated with the cognitive development

Cognitive development

Cognitive development is a field of study in neuroscience and psychology focusing on a child's development in terms of information processing, conceptual resources, perceptual skill, language learning, and other aspects of brain development and cognitive psychology compared to an adult's point of...

and socialization

Socialization

Socialization is a term used by sociologists, social psychologists, anthropologists, political scientists and educationalists to refer to the process of inheriting and disseminating norms, customs and ideologies...

of those engaged in developmental processes and the young. Play often entertains props

Theatrical property

A theatrical property, commonly referred to as a prop, is an object used on stage by actors to further the plot or story line of a theatrical production. Smaller props are referred to as "hand props". Larger props may also be set decoration, such as a chair or table. The difference between a set...

, tools, animals, or toy

Toy

A toy is any object that can be used for play. Toys are associated commonly with children and pets. Playing with toys is often thought to be an enjoyable means of training the young for life in human society. Different materials are used to make toys enjoyable and cuddly to both young and old...

s in the context of learning

Learning

Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

and recreation

Recreation

Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be "fun"...

. That is, some hypothesize that play is preparation of skills that will be used later. Others appeal to modern findings in neuroscience to argue that play is actually about training a general flexibility of mindincluding highly adaptive practices like training multiple ways to do the same thing, or playing with an idea that is "good enough" in the hopes of maybe making it better.

Some play has clearly defined goals and when structured with rules is called a "game

Game

A game is structured playing, usually undertaken for enjoyment and sometimes used as an educational tool. Games are distinct from work, which is usually carried out for remuneration, and from art, which is more often an expression of aesthetic or ideological elements...

", whereas, other play exhibits no such goals nor rules and is considered to be "unstructured" in the literature. Play promotes broaden and build behaviors as well as mental states of happiness

Happiness

Happiness is a mental state of well-being characterized by positive emotions ranging from contentment to intense joy. A variety of biological, psychological, religious, and philosophical approaches have striven to define happiness and identify its sources....

including flow

Flow (psychology)

Flow is the mental state of operation in which a person in an activity is fully immersed in a feeling of energized focus, full involvement, and success in the process of the activity. Proposed by Mihály Csíkszentmihályi, the positive psychology concept has been widely referenced across a variety of...

.

Play has traditionally been given little attention by behavioral ecologists. Edward O. Wilson wrote in Sociobiology
Sociobiology: The New Synthesis
Sociobiology: The New Synthesis is a book written by E. O. Wilson, which started the sociobiology debate, one of the great scientific controversies in biology of the 20th century...

that "No behavior has proved more ill-defined, elusive, controversial and even unfashionable than play." Though it received little attention in the early decades of ethology, and instead only existed as a matter of study within human psychology, there is now a considerable body of scientific literature

Scientific literature

Scientific literature comprises scientific publications that report original empirical and theoretical work in the natural and social sciences, and within a scientific field is often abbreviated as the literature. Academic publishing is the process of placing the results of one's research into the...

resulting from research

Research

Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...

on the subject. Play does not have the central theoretical framework that exists in other areas of biology.

Ethologists frequently divide play into three general categories: Social play, locomotor play and object play. Locomotor play is the pretend playing that a very young animal participates in when alone. The jumping and spinning characteristic of locomotor play can best be seen in young goat

Goat

The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...

s. Researchers have theorized that locomotor play helps the cells in the cerebellum

Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...

of the brain to develop connections. Types of play listed by psychiatrist Dr. Stuart Brown expand upon these basic categories to include: fantasy and transformational play as well as body, object, social. The National Institute for Play describes the previous five play types, as well as the play types attunement and narrative.

Definitions

Play is essentially an activity which is enjoyed alone, though it can involve others, who perceive the play from their perspective and may not be in the mood for play. Play is most commonly associated with juvenile activities, and when engaged in by an adult they may be described as "childish" or "child at heart." Play can consist of an amusing, pretend or imaginary activity alone or with another.

A concerted endeavor has been made to identify the qualities of play, but this task is not without its ambiguities. For example, play is commonly perceived as a frivolous and non-serious activity; yet juveniles at play often display a transfixed seriousness and entrancing absorption

Trance

Trance denotes a variety of processes, ecstasy, techniques, modalities and states of mind, awareness and consciousness. Trance states may occur involuntarily and unbidden.The term trance may be associated with meditation, magic, flow, and prayer...

while engaged in it. Other criteria of play include a relaxed pace and freedom versus compulsion. Yet play seems to have its intrinsic constraints, as in, "You're not playing fair."

When play is structured and goal-orientated it is often presented as a game. Play can also be seen as the activity of rehearsing life events, e.g., young animals play fighting. Play may also serve as a pretext, allowing people to explore reactions of others by engaging in playful interaction. Flirting is an example of such behavior. These and other concepts or rhetorics of play are discussed at length by Brian Sutton-Smith

Brian Sutton-Smith

Brian Sutton-Smith is a play theorist who has spent his lifetime attempting to discover the cultural significance of play in human life, arguing that any useful definition of play must apply to both adults and children. He demonstrates that children are not innocent in their play and that adults...

in the book The Ambiguity of Play. Sometimes play is dangerous, such as in extreme sport

Extreme sport

An extreme sport is a popular term for certain activities perceived as having a high level of inherent danger...

s. This type of play could be considered stunt

Stunt

A stunt is an unusual and difficult physical feat, or any act requiring a special skill, performed for artistic purposes in TV, theatre, or cinema...

play, whether engaging in play fighting, sky-diving, or riding a device at a high speed in an unusual manner.

The seminal text in the field of play studies is Homo Ludens
Homo Ludens
Homo Ludens or "Man the Player" is a book written in 1938 by Dutch historian, cultural theorist and professor Johan Huizinga.It discusses the importance of the play element of culture and society....

by Johan Huizinga

Johan Huizinga

Johan Huizinga , was a Dutch historian and one of the founders of modern cultural history.-Life:Born in Groningen as the son of Dirk Huizinga, a professor of physiology, and Jacoba Tonkens, who died two years after his birth, he started out as a student of Indo-Germanic languages, earning his...

. Huizinga defined play as follows:
This definition of play as constituting a separate and independent sphere of human activity is sometimes referred to as the "magic circle

Magic circle

A magic circle is circle or sphere of space marked out by practitioners of many branches of ritual magic, which they generally believe will contain energy and form a sacred space, or will provide them a form of magical protection, or both. It may be marked physically, drawn in salt or chalk, for...

" notion of play, and attributed to Huizinga, who does make reference to the term at some points in Homo Ludens
Homo Ludens
Homo Ludens or "Man the Player" is a book written in 1938 by Dutch historian, cultural theorist and professor Johan Huizinga.It discusses the importance of the play element of culture and society....

. According to Huizinga, within play spaces, human behavior is structured by very different rules: e.g., kicking (and only kicking) a ball in one direction or another, using physical force to impede another player (in a way which might be illegal outside the context of the game).

Another classic in play theory is Man, Play and Games
Man, Play and Games
Man, Play and Games is a 1961 book, and the seminal work of the French Sociologist Roger Caillois, a translation of Les jeux et les hommes . It is an influential book on the sociology of play and games, or rather in Caillois' terms sociology derived from play...

by Roger Caillois

Roger Caillois

Roger Caillois was a French intellectual whose idiosyncratic work brought together literary criticism, sociology, and philosophy by focusing on subjects as diverse as games, play and the sacred...

. Borrowing much of his definition from Huizinga, Caillois coined several formal sub-categories of play, such as alea (games of chance) and ilinx (vertigo or thrill-seeking play).

According to Stephen Nachmanovitch

Stephen Nachmanovitch

Stephen Nachmanovitch is a musician, author, computer artist, and educator. He is an improvisational violinist, and writes and teaches about improvisation, creativity, and systems approaches in many fields of activity.-Biography:...

, play is the root and foundation of creativity in the arts and sciences also as in daily life.
A notable contemporary play theorist is Jesper Juul who works on both pure play theory and the application of this theory to computer game studies. The theory of play and its relationship with rules and game design is also extensively discussed by Katie Salen

Katie Salen

Katie Salen is a game designer, animator, and design educator. She is a professor in the DePaul University College of Computing and Digital Media. She has taught at Parsons The New School for Design the University of Texas at Austin, New York University, and the Rhode Island School of Design...

and Eric Zimmerman

Eric Zimmerman

Eric Zimmerman is a game designer and the co-founder and CEO of Gamelab, a computer game development company, which is known for the game Diner Dash. Each year Zimmerman hosts the Game Design Challenge at the Game Developers Conference...

in their book Rules of Play: Game Design Fundamentals. In computer games

Computer Games

"Computer Games" is a single by New Zealand group, Mi-Sex released in 1979 in Australia and New Zealand and in 1981 throughout Europe. It was the single that launched the band, and was hugely popular, particularly in Australia and New Zealand...

, the word gameplay

Gameplay

Gameplay is the specific way in which players interact with a game, and in particular with video games. Gameplay is the pattern defined through the game rules, connection between player and the game, challenges and overcoming them, plot and player's connection with it...

is often used to describe the concept of play.

Symbolic play uses one thing to stand for another and shows the child's ability to create mental images. There are three types of symbolic play: dramatic play, constructive play, and playing games with rules.

Researchers at the National Institute for Play are creating a clinical, scientific framework for play. They describe seven patterns of play which indicate the range of activities and states of being which play encompasses. References for each type of play are also listed.

James Findlay

James Findlay

James Findlay may refer to:* James Findlay , Canadian Member of Parliament* James Findlay , Canadian politician...

, a Social Educator, defines play as "intelligence," suggesting further that play is the "meta intelligence" behind, together with, and changing, the various forms of intelligences people have. He argues that play intelligence is not a form of intelligence, it is intelligence in all its forms. He is known for his 3-dimensional models which demonstrate the principles of how intelligence and play function together.

Purpose

Evolutionary psychologists believe that there must be an important benefit of play, since there are so many reasons to avoid it. Animals are often injured during play, become distracted from predators, and expend valuable energy. In rare cases, play has even been observed between different species that are natural enemies such as a polar bear

Polar Bear

The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...

and a dog. It has also been noted that play seems to be higher up on a hierarchy of needs. For example, stressed and starving animals do not play (making it a broaden and build behavior).

One theoryPlay as preparationwas inspired by the observation that play often mimics adult themes of survival. Predators such as lion

Lion

The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...

s and bear

Bear

Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...

s play by chasing, pouncing, pawing, wrestling, and biting, as they learn to stalk and kill prey. Prey animals such as deer

Deer

Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

and zebra

Zebra

Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

s play by running and leaping as they acquire speed and agility. Hoofed mammals also practice kicking their hind legs to learn to ward off attacks. While mimicking adult behavior, attacking actions such as kicking and biting are not completely fulfilled so that they won't injure each other. In social animals, playing might also help to establish dominance rankings among the young to avoid conflicts as adults. On the other hand, this view runs into some problems; the behaviors practiced are often quite different, or even exactly the opposite of those required in the equivalent real life situation.

Researcher John Byers describes how the amount of time spent at play for many mammals (e.g. rats and cats) peaks around puberty, and then drops off. This corresponds to the development of their cerebellum

Cerebellum

, suggesting that play is not so much about practicing the exact behaviors, as much as building general connections in the brain. Research by Sergio Pellis and colleagues discovered that play may shape the brain in other ways. Young mammals have an overabundance of brain cells in their cerebrum (the outer areas of the brainpart of what distinguishes mammals). Play has been evidenced to help the brain clean up this excess of cells, resulting in the more effective cerebrum of maturity.

Marc Bekoff describes a Flexibility Hypothesis which attempts to incorporate these newer neurological findings. It argues that play helps animals learn to switch and improvise all behaviors more effectively. Animal researcher Marek Spinka believes that playing helps animals learn to handle new and surprising events. There may, however, be other ways to acquire even these benefits of playthe concept of equifinality

Equifinality

Equifinality is the principle that in open systems a given end state can be reached by many potential means. The term is due to Ludwig von Bertalanffy, the founder of General Systems Theory. He prefers this term, in contrast to "goal", in describing complex systems' similar or convergent behavior...

. The idea is that the social benefits of play for many animals, for example, could instead be garnered by grooming. Patrick Bateson maintains that equifinality is exactly what play teaches. In accordance with the flexibility hypothesis, play may teach animals to avoid "false endpoints." In other words, they will harness the childlike tendency to keep playing with something that works "well enough," eventually allowing them to come up with something that might work better, if only in some situations. This also allows mammals to build up various skills that could come in handy in entirely novel situations.

Peter Smith warns against a "play ethos." He says we must keep things in perspective, and let real evidencerather than wishful thinkingguide our beliefs about play.

Childhood and play

Learning through play

-Learning Through Play :Learning Through Play is a term widely used in education and psychology to describe how a child can learn to make sense of the world around them...

has been long recognized as a critical aspect of childhood

Childhood

Childhood is the age span ranging from birth to adolescence. In developmental psychology, childhood is divided up into the developmental stages of toddlerhood , early childhood , middle childhood , and adolescence .- Age ranges of childhood :The term childhood is non-specific and can imply a...

and child development

Child development

Child development stages describe theoretical milestones of child development. Many stage models of development have been proposed, used as working concepts and in some cases asserted as nativist theories....

. Some of the earliest studies of play started in the 1890s with G. Stanley Hall

G. Stanley Hall

Granville Stanley Hall was a pioneering American psychologist and educator. His interests focused on childhood development and evolutionary theory...

, the father of the child study movement that sparked an interest in the developmental, mental and behavioral world of babies and children. The American Academy of Pediatrics

American Academy of Pediatrics

The American Academy of Pediatrics is the major professional association of pediatricians in the United States. The AAP was founded in 1930 by 35 pediatricians to address pediatric healthcare standards. It currently has 60,000 members in primary care and sub-specialist areas...

(AAP) published a study in 2006 entitled: "The Importance of Play in Promoting Healthy Child Development and Maintaining Strong Parent–Child Bonds". The report states: "free and unstructured play is healthy andin factessential for helping children reach important social, emotional, and cognitive developmental milestones as well as helping them manage stress and become resilient."

Many of the most prominent researchers in the field of psychology (including Jean Piaget

Jean Piaget

Jean Piaget was a French-speaking Swiss developmental psychologist and philosopher known for his epistemological studies with children. His theory of cognitive development and epistemological view are together called "genetic epistemology"....

, William James

William James

William James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...

, Sigmund Freud

Sigmund Freud

Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...

, Carl Jung

Carl Jung

Carl Gustav Jung was a Swiss psychiatrist and the founder of Analytical Psychology. Jung is considered the first modern psychiatrist to view the human psyche as "by nature religious" and make it the focus of exploration. Jung is one of the best known researchers in the field of dream analysis and...

and Lev Vygotsky

Lev Vygotsky

Lev Semyonovich Vygotsky was a Soviet psychologist, the founder of cultural-historical psychology, and the leader of the Vygotsky Circle.-Biography:...

) have viewed play as endemic to the human species; indeed, the attributions projected upon an imaginary friend by children are key to understanding the construction of human spirituality and it pantheon(s) of deification (and demonization

Demonization

Demonization is the reinterpretation of polytheistic deities as evil, lying demons by other religions, generally monotheistic and henotheistic ones...

).

Play is explicitly recognized in Article 31 of The Convention on the Rights of the Child

Convention on the Rights of the Child

The United Nations Convention on the Rights of the Child is a human rights treaty setting out the civil, political, economic, social, health and cultural rights of children...

(adopted by the General Assembly of the United Nations

United Nations

The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

, November 29, 1989). which states:

Parties recognize the right of the child to rest and leisure, to engage in play and recreational activities appropriate to the age of the child and to participate freely in cultural life and the arts.
Parties shall respect and promote the right of the child to participate fully in cultural and artistic life and shall encourage the provision of appropriate and equal opportunities for cultural, artistic, recreational and leisure activities.

Childhood "play" is also seen by Sally Jenkinson (author of The Genius of Play) to be an intimate and integral part of childhood development. "In giving primacy to adult knowledge, to our 'grown-up' ways of seeing the world, have we forgotten how to value other kinds of wisdom? Do we still care about the small secret corners of children's wisdom?"

Modern research in the field of "affective neuroscience" has uncovered important links between role playing and neurogenesis in the brain. Sociologist Roger Caillois

Roger Caillois

Roger Caillois was a French intellectual whose idiosyncratic work brought together literary criticism, sociology, and philosophy by focusing on subjects as diverse as games, play and the sacred...

used the word ilinx
Ilinx
Ilinx is a kind of play, described by sociologist Roger Caillois, a major figure in game studies. Ilinx creates a temporary disruption of perception, as with vertigo, dizziness, or disorienting changes in direction of movement....

to describe the momentary disruption of perception that comes from forms of physical play that disorient the senses, especially balance.

In addition, evolutionary psychologists have begun to expound the phylogenetic relationship between higher intelligence in humans and its relationship to play.

Stevanne Auerbach

Stevanne Auerbach also known as Dr. Toy, is an American educator, child development expert, writer and toyologist. She is known for being a consummate gadfly of the toy industry. After more than thirty years in the field of toys, she was named a Wonder Woman of Toys by Playthings Magazine...

mentions the role of play therapy

Play therapy

Play therapy is generally employed with children aged 3 through 11 and provides a way for them to express their experiences and feelings through a natural, self-guided, self-healing process...

in treating children suffering from traumas, emotional issues, and other problems. She also emphasizes the importance of toys with high play value

Play value

Play value is the essential value of a toy or game for play.The term is frequently employed in the field of child development and playwork for the assessment of toys, games, equipment and spaces. When they are fun and engaging, playthings and spaces are said to have play value. Those that are...

for child development and the role of the parent in evaluating toys and being the child's play guide.

Playtime

American historian Howard Chudacoff has studied the interplay between parental control of toys and games and children's drive for freedom to play. In the colonial era, toys were makeshift and children taught each other very simple games with little adult supervision. The market economy of the 19th century enabled the modern concept of childhood as a distinct, happy life stage. Factory-made dolls and doll houses delighted the girls. Organized sports filtered down from adults and colleges, as boys made good with a bat, a ball and an impromptu playing field. In the 20th century teenagers were increasingly organized into club sports supervised and coached by adults, with swimming taught at summer camps. The New Deal's WPA

WPA

- Agencies and organizations :*World Pool-Billiard Association*World Psychiatric Association- United States :*Washington Project for the Arts*Women's Prison Association...

built thousands of local playgrounds and ball fields, promoting softball especially as a sport for everyone of all ages and sexes, as opposed to increasingly professionalized adult sports. By the 21st century, Chudacoff notes, the old tension between controls and freedom was being played out in cyberspace.

Play and adulthood

Researcher Stuart Brown says that play isn't important to children, it's important to humans (or for that matter, all high functioning animals). The broaden and build behaviors it fosters may have even greater value for adults than children. The mental state of flow

Flow (psychology)

is also a major component of play, and has itself been associated with things like creativity

Creativity

Creativity refers to the phenomenon whereby a person creates something new that has some kind of value. What counts as "new" may be in reference to the individual creator, or to the society or domain within which the novelty occurs...

and happiness. Brown often quotes Brian Sutton-Smith's insight: "the opposite of play is not work, it is depression." Examples of adult play abound (e.g. the arts

The arts

The arts are a vast subdivision of culture, composed of many creative endeavors and disciplines. It is a broader term than "art", which as a description of a field usually means only the visual arts. The arts encompass visual arts, literary arts and the performing arts – music, theatre, dance and...

, but also curiosity driven science

Basic Research

Basic Research is an herbal supplement and cosmetics manufacturer based in Salt Lake City, Utah that distributes products through a large number of subsidiaries. In addition, their products are sold domestically and internationally through a number of high-end retailers. Dennis Gay is the...

).

Tim Brown explains that values like a bit of shamelessness during the creative process is extremely important in adult designers.

Play may allow people to practice useful habits like learned optimism

Learned optimism

Learned optimism is the idea in positive psychology that a talent for joy, like any other, can be cultivated. It is contrasted with learned helplessness. Learning optimism is done by consciously challenging any negative self talk.- Overview :...

, which might help manage existential fears

Terror management theory

Terror Management Theory , in social psychology, states that all human behavior is motivated by the fear of mortality. The theory purports to help explain human activity both at the individual and societal level...

. Play also offers the opportunity to learn things that may not have otherwise been explicitly or formally taught (e.g. how to use, and deal with, deceit and misinformation). Thus, even though play is only one of many habits of an effective adult, it remains a necessary one.

External links

The Play Foundation
The National Institute for Play
Design for Play – A play environment and outdoor classroom design firm that specializes in designing playgrounds based on child development and brain development research.
Arquetipo Ludi (Spanish)
IPA World Home (International Play Association: Promoting the Child's Right to Play)
Creative Play
Brown, Stuart (2008) Why play is vital – no matter your age, TEDtalks, TED.com

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.