The American ethologist and evolutionary biologist, Gordon M Burghardt (1941-date), identified five necessary criteria in defining play in his 2005 book, ‘The Genesis of Play: testing the limits’.
When doing so, Burghardt points out that play, across the animal world, consumes a huge amount of time and energy and is therefore clearly an important behaviour across species.
However, there existed at the time of his writing no agreed objective definition of play as a phenomenon that crossed species boundaries. This would require a definition that could objectively encompass the play behaviour of all animals, including human beings.
Doing so is difficult in part due to the fact that many definitions of play amongst humans (specially children) incorporate an element of fun or joy, yet this is difficult concept to interpret in the behaviour of non-human animals.*
As he writes in a later 2010 paper for the American Journal of Play, “We may all agree that we have seen, say, a dog or a monkey play, but it turns out that we only do so because we anthropomorphise their behaviour and its underlying emotion.” (The Comparative Reach of Play and Brain: perspective, evidence, and implications 2010:345).
Searching for patterns in the play of multiple species, he therefore developed his definition of play around five criteria that could be applied objectively to any given behaviour in any species concluding that only if the activty met all of the following five criteria could it be considered ‘play’.
He summarised these into a short definition of play as,
“Play is a repeated behaviour that is incompletly functional in the context or at the age in which it is performed and is initiated voluntarly when the animal or person is is a relaxed low-stress setting."
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In more detail the five criteria are:
in other words, it is not essential to immediate needs or survival at the moment it is performed
in other words, the behaviour does not seek any extrinsic reward; it is done in the moment, spontaneous and voluntarily. It is, instead, internally motivated, and is pleasurable or rewarding for the individual.
in other words, the behaviour does not require a complete imitation of a ‘real behaviour’: it may be incomplete, out of sequence, exaggerated, or precocious yet still hold the attention of the individual.
in other words, the behavior might be repeated often but not in a rigid way; it is still subject to change and adaptation meaning that the same basic behaviour might be subject to subtle change each time it is performed.
in other words, the behaviour is carried when the animal is in a ‘low stress’ state or ‘relaxed field’ (a term first coined by the Swiss ethologist Gustav Bally in 1945) where it is safe from immediate threats, predators, etc; and is well-fed and healthy.
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Photo: Gordon Burghardt
See also Relaxed Field (to come), Flow Theory (to come)
*one notable exception to this is research by Jaan Panksepp into the play of rats, who discovered that rats do indeed laugh while playing but at a frequency inaudible to humans.
