The Rational Imagination: How People Create Alternatives to Reality by Ruth Byrne.
This one looks interesting and relevant to my project. Byrne will discuss the role of imagination in rational thought generally and more specifically the role it plays in counterfactual thinking. For example, "How might my life have gone if I had started grad school immediately after college?"
The Work of Imagination by Paul Harris
This one came up in a lot of bibliographies, so I thought it might be important. Harris is a developmental psychologist and this book presents the research on the role of imagination in the cognitive and emotional development of children.