This text is an introduction to some of the basic ideas and controversies which have arisen from key studies in psychology. These studies have been fundamental in shaping psychology as both a practical and academic discipline, and this book focuses on 20 of them in connection with the following topics: cognitive psychology; social psychology; developmental psychology; physiological psychology; and the psychology of individual differences. An outline of how research in each area has developed is provided and each one of the 20 key studies are described at the end of each section. Also featured are everyday examples and anecdotes, making the research accessible to the reader.