Glenn Weisfeld & Carol Cronin Weisfeld (2016)
This paper begins with a list of commonly recognized forms of play and a discussion of definitions of play. This is followed by an overview of the ontogeny, phylogeny, mechanisms, and possible functions of human play. Next the question of whether or not play should be regarded as a separate emotion from interest is addressed. Play resembles the emotion of interest (or curiosity) in its affects and cognitive elicitors. Play differs from interest in exhibiting somewhat distinctive behavioral, visceral, and expressive emotional properties. This evidence, together with phylogenetic information, suggests that interest, exploration, and play constitute the same basic emotion, with exploration being an evolutionary offshoot of interest and play an offshoot of exploration.