“Blindspot” is a metaphor to capture that portion of the mind that houses hidden biases. The authors use it to ask about the extent to which social groups—without our awareness or conscious control—shape our likes and dislikes, our judgments about people’s character, abilities, and potential.

In "Blindspot," hidden biases are revealed through hands-on experience with the method that has revolutionized the way scientists are learning about the human mind and that gives us a glimpse into what lies within the metaphoric blindspot— the Implicit Association Test. 

The title’s “good people” are the many people—the authors included—who strive to align their behavior with their good intentions. The aim of "Blindspot" is to explain the science in plain enough language to allow well-intentioned people to better achieve that alignment. Venturing into this book is an invitation to understand our own minds.

Source: the "Blindspot" website.