At first glance, quantum mechanics and behavioural science may appear to belong to entirely separate domains-one rooted in subatomic particles and mathematical formalisms, the other in human thoughts, decisions and emotions. However, recent research reveals a surprising and powerful connection between them. This book investigates that connection through quantum models of cognition and decision-making, illustrating how principles from quantum theory can help us understand ambiguity, bias and perception in ways that classical logic cannot. This book introduces a practical and computationally accessible framework based on quantum theory. Readers are invited not only to explore vivid case studies-from visual illusions in video games to decision biases in politics and finance-but also to engage directly with the methods. Supporting computer code is provided so that readers can experiment with their own models and ideas immediately after reading. Combining insights from physics, psychology, artificial intelligence and economics, this work offers an innovative perspective on how we think, choose and interact as individuals and societies.