Science moves through history along many routes and at many speeds. Slow times occur when the pace of scientific discovery seems to stagnate, making little or no progress. Then those exciting, dynamic periods suddenly burst upon the scientific scene; new breakthroughs spark waves of dialogue, attention, research, and progress. These discoveries quite literally change what we know about how the world works. The history of psychology is no different from any other science. Many studies of human behavior have made remarkable and lasting impacts on the various disciplines that comprise the science of psychology. The findings generated from these studies have changed our knowledge of human behavior, and they have set the stage for countless subsequent projects and research programs. Even when the results of some of these pivotal studies have later been drawn into controversy and question, their effect and influence in a historical context never diminishes. They continue to be cited in new articles; they continue to be the topic of academic discussion; they continue to form the foundation for textbook chapters; and they continue to hold a special place in the minds of psychologists.
The concept for this book grew out of my many years of teaching psychology. Psychology textbooks are based on those key studies that have shaped the science of psychology over its relatively brief history. Textbooks, however, seldom give the original studies the attention they richly deserve. Usually the research processes are summarized and diluted to the point that little of the life and excitement of the discoveries remains. Sometimes, methods and findings are reported in way that can even mislead the reader about the study's true impact and influence. This is in no way a criticism of the textbook writers who work under length constraints and must make many difficult choices about what gets included and in how much detail. The situation is, however, unfortunate, because the foundation of all of psychology is research, and through a century of ingenious and elegant studies, our knowledge and understanding of human behavior have been expanded and refined to the level of sophistication that exists today.
This book is an attempt to fill the gap between the psychology textbooks and the research that made them possible. It is a journey through the headline history of psychology. My hope is that the way the 40 chosen studies are presented will bring them back to life, so that you can experience them for yourself. This book is intended for anyone who wishes a greater understanding of the true roots of psychology.
CHOOSING THE STUDIES
The studies included in this book were carefully chosen from those found in psychology texts and journals and from those suggested by leading authorities in psychology's many subfields. The number wasn't planned, but as the studies were selected, 40 seemed to be about right both from a historical point of view and in terms of length. The studies chosen are arguably the most famous, the most important, or the most influential in the history of psychology. I use the word arguably, because many who read this book may wish to dispute some of the choices. One thing is sure: No single list of 40 studies would satisfy everyone. However, the studies included here are the ones that continue to be cited most frequently, stirred up the most controversy when they were published, sparked the most subsequent related research, opened new fields of psychological exploration, or changed most dramatically our knowledge of human behavior. These studies are organized according to the major psychology branch into which they best fit, including Biology and Human Behavior; Consciousness; Learning and Conditioning; Intelligence, Cognition, and Memory; Human Development; Emotion and Motivation; Personality; Psychopathology; Psychotherapy; and Social Psychology.
PRESENTING THE STUDIES
You will find that a basic format is used consistently throughout the book to promote a clear understanding of each study presented. Each reading contains:
- An exact, readily available reference for where the original study can be found.
- A brief introduction summarizing the background in the field leading up to the study and the reasons the researcher carried out the project.
- The theoretical propositions or hypotheses on which the research rests.
- A detailed account of the experimental design and methods used to carry out the research, including, where appropriate, who the subjects were and how they were recruited; descriptions of any apparatus and materials used; and the actual procedures followed in carrying out the research.
- A summary of the results of the study in clear, understandable, nontechnical, nonstatistical, no jargon language.
- An interpretation of the meaning of the findings based on the author's own discussion in the original article.
- The significance of the study to the field of psychology.
- A brief discussion of supportive or contradictory follow-up research findings and subsequent questioning or criticism from others in the field.
- A sampling of recent applications and citations of the study in others' articles to demonstrate its continuing influence.
- References for additional and updated reading relating to the study.
Often, scientists speak in languages that are not easily understood (even by other scientists!). The primary goal of this book is to make these discoveries meaningful and accessible to the reader and to allow you to experience the excitement and drama of these remarkable and important discoveries. Where possible and appropriate, I have edited and simplified some of the studies presented here for ease of reading and understanding. However, this has been done carefully, so that the meaning and elegance of the work is preserved and the impact f the research is distilled and clarified.
NEW TO THE FIFTH EDITION
This fifth edition of Forty Studies contains many significant and substantive changes and additions. You will find two important new studies about intelligence and gender. In addition, all the Recent Applications sections near the end of each reading have been updated to reflect the numerous citations of each of the 40 studies during the three years since the completion of the fourth edition (2000-2003). In that brief, three-year time span, the 40 studies discussed in this edition have been cited nearly 3,000 times! A small sampling of those articles are briefly summarized throughout this edition to allow you to experience the ongoing influence of these 40 studies that changed psychology. All newly 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 fourth edition, I have continued to enjoy numerous conversations with, and helpful suggestions and counsel from, colleagues in many branches of psychological research about potential changes in the selection of studies for this new edition. Two highly influential studies I have been considering for some time have been mentioned frequently by fellow researchers, so I have included them in this edition. Although they have replaced other studies in previous editions, those studies are still available in their entirety on the Prentice Hall Web site at www.prenhall.com/psychology. 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 new articles represented a major shift in how we view a basic component of who we are as humans: our gender. Most of you today are familiar with the term androgyny and have at least some sense that it refers to individuals who display both masculine and feminine characteristics, attitudes, and behaviors. What you may not know is that the concept of androgyny was proposed in the early 1970s by Stanford psychologist Sandra Bem. Bem challenged the traditional view of gender that placed male and female at opposite ends of a single scale, thereby creating an "either-or" conceptualization of "healthy" gender identity based on the assumption, "If you are male you should be masculine and if you are female you should be feminine." Bern, however, saw this model as lacking in its ability to describe those people who possess more of a balance of both masculine and feminine traits. She referred to these individuals as androgynous (from "andro" meaning male, and "gyn" referring to female). Moreover, she argued that androgynous people may experience certain psychological advantages due to an enhanced ability to adapt to a greater range of life's situations than those who are either strongly masculine or strongly feminine. Bern's 1974 article, included in this edition, discusses her revolutionary theory and her development of a scale to measure gender on a two-dimensional scale, capable of tapping into masculinity, femininity, and androgyny.
The second new study incorporated into this edition represents a body of work that has transformed how we perceive another fundamental human attribute: our intelligence. Throughout the history of psychology, most social scientists and society in general saw intelligence as a single, general ability of which each of us possesses a different amount. This conceptualization of intelligence has led us to think of some people as "smarter" than others and nurtured the concept of IQ. In the early 1980s, however, Howard Gardner, of Harvard University, proposed that human intelligence is not such a unitary phenomenon, but rather consists of an amalgam of many different, specific sets of abilities, each of which may be interpreted as a "free standing" intelligence in and of itself. In his 1983 book that forms the basis of this new reading, Gardner articulated his eight criteria for defining a specific set of skills as an intelligence and proposed that humans possess at least seven distinct intelligences. This perspective on intelligence has become known as "multiple intelligences" or MI theory. Today, Gardner's MI theory (now containing eight intelligences), exerts a powerful influence in virtually all educational settings. It has broadened our understanding of human intelligence in ways that serve to enhance our ability to maximize our strengths, overcome our weaknesses, and celebrate an additional quality in the rich fabric of human diversity.
Finally, to accommodate the addition of these new studies within their appropriate psychological subfield, the discussion of Kohlberg's studies of moral development has been moved from the personality section to human development. Although an argument may be made for placing Kohlberg's work under either rubric, it probably fits better in development, next to the contributions of Piaget.
THE ETHICS OF RESEARCH INVOLVING HUMAN OR ANIMAL SUBJECTS
Without subjects, scientific research is virtually impossible. In physics, the subjects are subatomic particles; in botany, they are plants; in chemistry, they are the elements of the periodic table; and in psychology, the subjects are people. At times, certain research procedures or behaviors under study do not permit the use of human subjects, so animal subjects are substituted. However, the overall gal of animal research is to better understand humans, not just the animals themselves. In the following pages, you will be reading about research involving both human and animal subjects. Some of the studies may cause you to question the ethics of the researchers in regard to the procedures used with the subjects. Usually, when painful or stressful procedures are part of a study being discussed, the question of ethics is noted in the chapter. However, since this is such a volatile and topical issue, a brief discussion of the ethical guidelines followed by present-day psychologists is included here in preparation for some of the studies described in this book.
Research with Human Subjects
The American Psychological Association (APA) has issued strict and clear guidelines that researchers must follow when carrying out experiments involving human participants. A portion of the introduction to those guidelines reads as follows:
Psychologists strive to benefit those with whom they work and take care to do no harm. In their professional actions, psychologists seek to safeguard the welfare and rights of those with whom they interact . . . When conflicts occur among psychologists' obligations or concerns, they attempt to resolve these conflicts in a responsible fashion that avoids or minimizes harm . . . Psychologists uphold professional standards of conduct, clarify their professional roles and obligations, accept appropriate responsibility for their behavior, and seek to manage conflicts of interest that could lead to exploitation or harm . . . Psychologists respect the dignity and worth of all people, and the rights of individuals to privacy, confidentiality, and self-determination (excerpted from Ethical Principles of Psychologists and Code of Conduct, 2003; see www.apa.org/ethics/).
To adhere to those principles, researchers follow certain basic principles in carrying out all studies involving human subjects:
- Informed consent. A researcher must explain to potential subjects what the experiment is about and what procedures will be used so that the individual is able to make an informed decision whether to participate. If the person then agrees to participate, this is called informed consent. As you will see in this book, there are times when the true purposes of an experiment cannot be revealed because this would alter the behavior of the subjects and contaminate the results. In such cases, when deception is used, a subject still must be given adequate information for informed consent, and the portions of the experiment that are hidden must be justifiable based on the importance of the potential findings.
- Freedom to withdraw at any time. All human subjects in all research projects must know that they may withdraw freely from the study at any time. This may appear to be an unnecessary rule, because it would seem obvious that any subject who is too uncomfortable with the procedures can simply leave. However, this is not always so straightforward. For example, undergraduate students are often given course credit for participating as subjects in psychological experiments. If they feel that withdrawing will influence the credit they need, they may not feel free to do so. When subjects are paid to participate, if they are made to feel that their completion of the experiment is a requirement for payment, this could produce an unethical inducement to avoid withdrawing if they wish to do so. To avoid this problem, subjects should be given credit or paid at the beginning of the procedure just for showing up.
- Debriefing and protection from harm. Experimenters have the responsibility to protect their subjects from all physical and psychological harm that might be produced by the research procedures. Most psychological research involves methods that are completely harmless, both during and after the study. However, even seemingly harmless procedures can sometimes produce negative effects such as frustration, embarrassment, or concern. One common safeguard against those effects is the ethical requirement of debriefing. After subjects have completed an experiment, especially one involving any form of deception, they should be debriefed. During debriefing, the true purpose and goals of the experiment are explained to them, and they are given the opportunity to ask any questions about their experiences. If there is any possibility of lingering aftereffects from the experiment, the researchers should provide subjects with contact information for further discussion if necessary.
- Confidentiality. All results from subjects in experiments should be kept in complete confidence unless specific agreements have been made with the subjects. This does not mean that results cannot be reported and published, but this is done in such a way that individual data cannot be identified. Often, no identifying information is even acquired from subjects, and all data are combined to arrive at average differences among groups.
In research involving children, parental consent is required and the same ethical guidelines apply.
As you read through the studies included in this book, you may find a few studies that appear to have violated some of these ethical principles. These studies were carried out long before formal ethical guidelines existed and could not be replicated today. The lack of guidelines, however, does not excuse past researchers for abuses. Judgment of those investigators must now be made by each of us individually, and we must learn, as psychologists have, from past mistakes.
Research with Animal Subjects
One of the hottest topics of discussion in and outside of the scientific community is the question of the ethics of animal research. Animal-rights groups are growing in number and are becoming increasingly vocal and militant. More controversy exists today over animal subjects than human subjects, probably because animals cannot be protected, as humans can, with informed consent, freedom to withdraw, or debriefing. Additionally, the most radical animal rights activists take the view that all living things are ordered in value by their ability to .s se pain. In this conceptualization, animals are equal in value to humans and, therefore, any use of animals by humans is seen as unethical. This use includes eating a chicken, wearing leather, and owning pets (which, according to some animal-rights activists, is a form of slavery).
At one end of the spectrum, many people believe that research with animals is inhumane and unethical, and should be prohibited. However, nearly all scientists and most Americans believe that the limited and humane use of animals in scientific research is necessary and beneficial. Many lifesaving drugs and medical techniques have been developed through the use of animal experimental subjects. Animals have also often been subjects in psychological research to study issues such as depression, brain development, overcrowding, and learning processes. The primary reason animals are used in research is that to carry out similar research on humans clearly would be unethical. For example, suppose you wanted to study the effect on brain development and intelligence of raising infants in an enriched environment with many activities and toys, versus an impoverished environment with little to do. To assign human infants to these different conditions would simply not be possible. However, most people would agree that rats could be studied without major ethical concerns to reveal findings potentially important to humans (see the reading in this book on research such as this by Rosenzweig and Bennett).
The American Psychological Association, in addition to its guidelines on human subjects, has strict rules governing research with animal subjects designed to ensure humane treatment. These rules require that research animals receive proper housing, feeding, cleanliness, and health care. All unnecessary pain to the animal is prohibited. A portion of the APA's Guidelines for the Ethical Conduct in the Care and Use of Animals (2004) reads as follows:
Animals are to be provided with humane care and healthful conditions during their stay in the facility . . . . Psychologists are encouraged to consider enriching the environments of their laboratory animals and should keep abreast of literature on well-being and enrichment for the species with which they work .... When alternative behavioral procedures are available, those that minimize discomfort to the animal should be used. When using aversive conditions, psychologists should adjust the parameters of stimulation to levels that appear minimal, though compatible with the aims of the research. Psychologists are encouraged to test painful stimuli on themselves, whenever reasonable (see www.apa.org/science/anguide.html).
In this book, several studies involve animal subjects. In addition to the ethical considerations of such research, there are also difficulties in generalizing from animal findings to humans. These issues are discussed within each chapter that includes animal research. Each individual, whether a researcher or a student of psychology, must make his or her own decisions about animal research in general and the justifiability of using animal subjects in any specific instance. If you allow for the idea that animal research is acceptable under some circumstances, then, for each study involving animals in this book, you must decide if the value of the study's findings supports the methods used.
One final note related to this issue involves a development in animal research that is a response to public concerns about potential mistreatment. The city of Cambridge, Massachusetts, one of the major research centers of the world with institutions such as Harvard University and MIT, created the position of Commissioner of Laboratory Animals within the Department of Health and Hospitals. This was the first such governmental position and is currently held by a veterinarian, Dr. Julie Medley. Cambridge is home to 22 research laboratories that house approximately 60,000 animals. The commissioner's charge is to ensure humane and proper treatment of all animal subjects in all aspects of the research process, from the animals' living quarters to the methods used in administering the research protocols. If a lab is found to be in violation of Cambridge's strict laws concerning the humane care of lab animals, the commissioner is authorized to impose fines of up to $300 per day. However, Dr. Medley says she has never had to impose the fine, because any facility that has been found in violation, willingly and quickly corrects the problem (personal communication, September 2003)
The studies you are about to experience in this book have benefited all of humankind in many ways and to varying degrees. The history of psychological research is a relatively short one, but it is brimming with the richness and excitement of discovering human nature.