Imaginary Playmates and Other Mental Phenomena of Children
Harvey, Nathan A. (Ipsilanti: Michigan State Normal College, 1918/2017)
The material for the discussion of the topics in the following pages has been drawn from individual reports and personal interviews with more than five hundred different persons whose experiences are recorded. I have the fullest confidence in the accuracy of the reports and the sincerity with which they were made. I knew each person intimately, and a personal interview permits a kind of cross questioning and comparison with the reports of others which it is impossible to employ in a written questionnaire. The reports upon which the following chapters are based are absolutely truthful, and as accurate as the circumstances will permit.

The House of Make-Believe: Children’s Play and the Developing Imagination
Singer, Dorothy G. and Jerome L. Singer (Hillsdale, NJ: Erlbaum, 1992)
In the most thorough attempt to cover all aspects of children’s make-believe, Dorothy and Jerome Singer examine how imaginative play begins and develops, from the infant’s first smiles to the toddler’s engagement in social pretend play. They provide intriguing examples and research evidence on the young child’s invocation of imaginary friends, the adolescent’s daring, rule-governed games, and the adult’s private imagery and inner thought. In chapters that will be important to parents and policymakers, the authors discuss television and the imagination, the healing function of play, and the effects of playfulness and creativity throughout the life span.

Television, Imagination, and Aggression: A Study of Preschoolers
Singer, Jerome L. and Dorothy G. Singer (Hillsdale, NJ: Erlbaum, 1984)

Imaginary Companions and the Children Who Create Them
Taylor, Marjorie (Oxford University Press, 2001)
Many parents delight in their child’s imaginary companion as evidence of a lively imagination and creative mind. At the same time, parents sometimes wonder if the imaginary companion might be a sign that something is wrong. Does having a pretend friend mean that the child is in emotional distress? That he or she has difficulty communicating with other children? In this fascinating book, Marjorie Taylor provides an informed look at current thinking about pretend friends, dispelling many myths about them.

Invisible Companions: Encounters with Imaginary Friends, Gods, Ancestors, and Angels
Wigger, J. Bradley (Stanford University Press, 2019)
From the US to Nepal, author J. Bradley Wigger travels five countries on three continents to hear children describe their invisible friends―one-hundred-year-old robins and blue dogs, dinosaurs and teapots, pretend families and shape-shifting aliens―companions springing from the deep well of childhood imagination. Drawing on these interviews, as well as a new wave of developmental research, he finds a fluid and flexible quality to the imaginative mind that is central to learning, co-operation, and paradoxically, to real-world rationality. Yet Wigger steps beyond psychological territory to explore the religious significance of the kind of mind that develops relationships with invisible beings. Alongside Cinderella the blue dog, Quack-Quack the duck, and Dino the dinosaur are angels, ancestors, spirits, and gods. What he uncovers is a profound capacity in the religious imagination to see through the surface of reality to more than meets the eye. Punctuated throughout by children’s colorful drawings of their see-through interlocutors, the book is highly engaging and alternately endearing, moving, and humorous. Not just for parents or for those who work with children, Invisible Companions will appeal to anyone interested in our mind’s creative and spiritual possibilities.