NEW TO THE SIXTH EDITION

This sixth edition of Forty Studies offers numerous noteworthy and substantive changes and additions. I have added two of the most influential studies in the history of psychology about how we perceive the world. The first is Robert Fantz`s revolutionary discovery of an ingenious method to allow us to study what very young infants "know" (from 1961). The second, Philip Zimbardo`s famous Stanford Prison Study (from the early 1970s) focuses on the powerful and controlling forces some situations can exert over our behavior.

In addition, the Recent Applications sections near the end of the readings have been updated. These sections sample the numerous recent citations of the 40 studies into the 21st century. The 40 studies discussed in this book are referred to in over 1000 research articles every year! A small sampling of those articles is briefly summarized throughout this edition to allow you to experience the ongoing influence of these 40 studies that changed psychology.

All these recently cited studies are fully referenced at the end of each reading along with other relevant sources. As you read through them, you will be able to appreciate the breadth and richness of the contributions still being made by the 40 studies that comprise this book.

Over the three years since completing the fifth edition, I have continued to enjoy numerous conversations with, and helpful suggestions from, colleagues in many branches of psychological research about potential changes in the selection of studies for this new edition. Two studies I have for some time considered including have been mentioned frequently by fellow researchers, so I have added them in this edition. Each of these two newly incorporated studies, in their own significant ways, expanded our perceptions of two very basic aspects of human nature and added to our knowledge of the complexity and diversity of the human experience.

One of the newly added studies in this edition provided a window into the perceptual and thinking abilities of infants. Of course, behavioral scientists have known for decades that infants` behaviors in relation to the world around them change and develop quickly in many ways. But just what do babies know? How do they think? How skilled are they at perceiving and processing events in their environment? You can imagine this is a difficult research challenge to overcome because infants cannot talk to you about what is going on in their brains. Instead, researchers must infer what infants perceive and how they think from their observable behaviors. In essence, this was how the famous Swiss psychologist, Jean Piaget, who is discussed in Chapter V of this book, formed his theories of early cognitive development in preverbal infants. In the early 1960s, Robert L. Fantz discovered a new way of allowing us to peer inside the perceptions of infants: looking at what they are looking at. It turns out that even very young infants prefer to look at certain objects or events over others. By measuring this behavior, referred to as preferential looking, researchers have been able to study infants` knowledge and perception in many and varied contexts.

This methodology, along with some enhancements to it (also pioneered by Fantz), remains today, nearly 50 years later, the most widely employed technique when psychologists and others wish to study the perceiving, thinking, and knowing processes of infants.

The second study added to this new edition is one of the most wellknown research undertakings in the history of psychology. Many would argue, and rightly so, that perhaps it should have been a mainstay of this book from the beginning. It is Philip Zimbardo`s famous "Stanford Prison Study." That said, the historical timing is perfect to include this study now because a renewed interest has arisen in this study and the inferences drawn from it over the past several years, due to the high news-profile prisoner scandals in Iraq and various U.S. prisoner policies relating to the "War on Terror." In basic psychological theory, two forces determine our behavior in a given situation: our internal, dispositional factors (that is, who we are) and the influences of the situation in which we are behaving. In his simulated prison study, Zimbardo set out to examine how ordinary people`s behavior might change when placed in a situation that carries with it a great deal of inherent power, in this case, a prison.

All the studies, regardless of vintage, discussed in the upcoming pages have one issue in common: research ethics. One of the most important building blocks of psychological science is a strict understanding and adherence to a clear set of professional ethical guidelines in any research involving humans or animals. Let`s consider briefly the ethical principles social scientists work

diligently to follow as they make their discoveries.