Psychological Science: Content, Methodology, History, and Profession

Kurt Pawlik & Mark Rosenzweig. The International Handbook of Psychology. Editor: Kurt Pawlik & Mark R Rosenzweig. Sage Publications. 2000.

Human Behavior and Experience

People have always had to study each other’ behavior closely, but it was only in the nineteenth century that psychology emerged as an academic and scientific discipline, and only in the twentieth century that it also became a major field of professional activity. References to the human mind and how it may operate and translate into overt behavior can be traced back to specimens of written history, poetry, and philosophical speculations dating centuries B.C.E. In this sense, as the German psychologist Hermann Ebbinghaus pointed out, psychology has a long past, although it has only a short history. During the last one hundred years, psychological science has made tremendous strides, both in understanding behavior and mental processes and in applying this to practical problems, for example, in education and health, in industry and other work contexts, and in personal guidance and psychotherapy. This book illustrates the current scope of psychological science, its fields of basic and applied research, its methods and theories, and the wide range of its professional-psychological activities. It covers such diverse fields as learning over the life span, emotions and emotional disorders, memory processes and knowledge acquisition, and interpersonal behavior and group conflicts. It does so in an international perspective, bringing together editors and authors from around the world and drawing upon psychological research and professional expertise from different regions so as to give a balanced presentation with respect to cultures and ethnicity.

Relations of Psychological Science to Common-Sense Psychology

Modern scientific psychology differs importantly from what has variously been called folk psychology, lay psychology, common-sense, or implicit psychology. Common observations have led to a rich store of examples and beliefs about behavior, so that psychological discoveries may at times seem to be merely restatements of the obvious. But as Kelley (1992, p. 13) has pointed out, what is claimed to be ‘obvious’ is not obvious at all. Often the opposite of a finding would also be accepted as equally obvious. Also, folk psychology often includes contradictory principles. For example, many languages have a saying equivalent to ‘You can’ teach an old dog new tricks’, and also another that holds ‘You’e never too old to learn.’ The task of scientific psychology is to determine which of the apparently contradictory principles is correct, or under what circumstances one or the other is correct, and to formulate general principles relating age to ability to learn various kinds of material or skills. To the extent that a theorist challenges an audience’ assumptions and practices, they will find the theory interesting, as Davis (1971, p. 311) pointed out. But even in the case of obvious beliefs, the role of scientific research is to add precision and reconcile apparent contradictions by identifying the conditions under which each of the different results will hold (Kelley, 1992, p. 15). Furthermore, comparative psychological research allows us to apply the methods of scientific inquiry to the study of folk psychology itself, yielding new insights into how people think people will behave, how they conceptualize human nature and behavior and its causes, including their own behavior.

As psychology began to develop as a scientific discipline and advance beyond folk concepts, it also led to unexpected discoveries and insights into human behavior, its evolution, its development, and its causes. A pertinent example is the discovery that a memory trace, once established, tends to persist in long-term memory. Failure to recall something from long-term memory is mainly (though not exclusively; see Estes, 1997) caused by faulty performance of memory search (retrieval) or recognition processes rather than genuine forgetting. It has been an important, far-reaching finding that past learning will not fade out by itself. Today this is widely recognized, for example in therapeutic practice, in the behavioral treatment of anxiety conditions. Here techniques have been developed to weaken learned fears, not by trying to erase the memory, but by enabling a patient to learn new, competing attitudes or behaviors. Another application of this same discovery led to modern techniques of neuropsychological rehabilitation of long-term memory performance in normal old-age.

In recent years, folk concepts about human behavior have become a focal point of research interests in connection with the notion of so-called indigenous psychology.

How should Psychology be Classified among the Disciplines?

Originally philosophy was the trunk of general knowledge from which the sciences branched off. Thus, what we call physics used to be called ‘natural philosophy’. In some countries there is still a tendency to assimilate psychology to philosophy, but in Europe and North America scientific psychology clearly diverged in its aims and methods from philosophy in the last century.

How is psychology classed among the sciences? An earlier (1991) and a more recent (1998) survey by the International Union of Psychological Science (IUPsyS) showed that psychology is classified differently in different countries and regions of the world. Some aspects of psychology suggest that it be classified with the biological sciences, whereas other aspects suggest that it belongs to the social sciences. The statutes of the IUPsyS state that it works to promote ‘the development of psychological science, whether biological or social, normal or abnormal, pure or applied’. Responses to the 1991 IUPsyS questionnaire show that in different places, psychology is classified as a natural science, a biological or life science, a medical science, a behavioral science, a social science, an educational science, a humanity, or in a class of its own. In two-thirds of the national responses to the IUPsyS survey, psychology was classified differently at different universities within the same country, and even within the same university there may be psychology departments in different schools or faculties. Half the respondents from industrialized countries classified psychology as a biological or life science, and so did 33% of those from developing countries. On the other hand, half of the respondents from industrialized countries (but neither Canada nor the United States) also reported that at least some of their universities classified psychology as a humanity, but only 24% from developing countries did so.

In some universities, psychology was given a class of its own in 45% of the industrialized countries, but this is true in only two (11%) of the developing countries in our sample. In the United States, publications of the National Science Board and the National Science Foundation put psychology in its own class; its neighbors are, on the one side, the life sciences (including agricultural sciences and medical sciences) and, on the other side, the social sciences (including economics, sociology/anthropology, and political science).

Notwithstanding the variety of classifications of psychology in different countries and different universities, and in view of the research programs of modern psychology, it would be more accurate either to acknowledge that the domain of psychology overlaps those of biological, behavioral, and social sciences or, as many organizations already do, to give psychological science a class of its own (Rosenzweig, 1992, pp. 7-8).

One way to integrate biological and social lines of thinking and research within the discipline of psychology is to recognize and combine the structural (largely biological) and content (largely social) aspects of behavior. The basic principles of associative learning, for example, as described in Chapter 7, originate largely in innate properties of the central nervous system that mediate learning. These structural properties hold throughout a species and even across many species. Similarly the neurophysiology of speech resides in basic neurobiological structures whose characteristics are revealed in the way children of different ethnic backgrounds acquire their culture’ language systems. At the same time, the nature and content of associations learned by any single person or the specificity of the sign system and grammar rules of any language are bound to culture and social milieus. Thus in the study of human learning or of language behavior, perspectives of structure and of content must become integrated, and the methodology of psychological science has to develop so as to provide for this approach from both a biological and a social perspective. As Pawlik (1994a) has argued, this combined sociobiological approach in the study of behavior makes for a unique role of psychology in the study of human nature (see also Section 1.3 below).

Growing Recognition of the Scientific Status of Psychology

The 1991 and 1998 IUPsyS surveys asked whether recognition of psychological research in the respondents’ countries was increasing, remaining the same, or decreasing. Twenty-six of the 38 national responses stated that recognition is increasing, and only one response said ‘decreasing.’

By now the national academies of science or similar organizations in most industrialized countries have psychologists among their members, and this is true for an increasing number of developing countries (Rosenzweig, 1992, Table 10, p. 62). The first psychologist was elected to the Third World Academy of Sciences in 1996. In 1982 the International Union of Psychological Science became a member of the International Council of Science (then called the International Council of Scientific Unions), the apex of international scientific organizations. Further evidence of recognition of the scientific status of psychology is presented and discussed by Rosenzweig (1992). A resource list of references on the state and development of psychology in different countries has been published by Imada (1996).

Dictionary Definitions of Psychology

Dictionary definitions of psychology in several countries of North America and Western Europe reflect general usage in defining psychology as a science, thus testifying to widespread acceptance of this status. Here are a few examples of such definitions:

The Oxford English Dictionary (2nd ed., 1989): 1.a. The science of the nature, functions, and phenomena of the human mind (formerly also of the soul) …

‘c. In mod. usage, the signification of the word has broadened to include (a) The scientific study of the mind as an entity and its relationship to the physical body, based on observations of the behaviour and activity aroused by specific stimuli; and (b) The study of the behaviour of an individual or of a selected group of individuals when interacting with the environment or in a given social context. So experimental psychology, the experimental study of the responses of an individual to stimuli; social psychology, the study of the interaction between an individual and the social group to which he belongs’ (vol. 12, p. 766).

The Random House College Dictionary (1984): ‘1. the science of the mind or of mental states and processes. 2. the science of human and animal behavior.’

The Larousse French dictionaries show a transition in definitions around 1960 from psychology as a branch of philosophy to psychology as a science. Emphasis on the scientific nature of modern psychology is also found, for example, in the Grande dizionario della lingua italiana (1988) or in the German Grosses Duden Lexikon (Bibliographisches Institut, 1969) and Brockhaus Enzyklopädie (Bibliographisches Institut, 1996).

Chinese dictionaries define psychology as ‘A science studying the objective laws of psychological activities’ (Xin Hua Dictionary, 1980) and list fields such as developmental psychology, physiological psychology, and social psychology, as well as applied fields such as educational psychology, industrial psychology, medical psychology, sports psychology, art psychology, aviation psychology, and so on (Ci Hai Dictionary, 1989).

Why does the Classification of Psychology Matter?

Plato wrote, ‘What a country honors will flourish there.’ Obtaining recognition of the scientific achievements of psychological research and its applications is both a reward for psychological investigators and practitioners and one of the conditions that fosters further achievements. Failure to obtain recognition for the scientific status of psychological research retards the further advance of such research and its applications. It also impairs recruitment of students to the field. Psychologists from various parts of the world testify to this, as the following examples show.

Writing from China and Hong Kong, Leung and Zhang (1995, p. 698) note ‘… that the classification of psychology has implications for its development. If psychology is classified as a science, funding is usually more adequate. The Institute of Psychology in China is under the Chinese Academy of Sciences, and the funding received is better than for other social sciences. In Hong Kong, psychology is classified as a laboratory-based subject, and funded better than economics and sociology. On the other hand, if psychology is grouped under humanities, equipment and technical support is often insufficient.’

Writing from Mexico, Diaz-Loving, Reyes-Lagunas and Diaz-Guerrero (1995) state that the fact that social sciences are considered there as part of humanities and not as sciences makes it difficult to obtain funding for research and hard to attract students and to obtain positions outside of academia for them.

In Australia, a report prepared for the National Committee of Psychology of the Australian Academy of Science (Australian Research Council Discipline Research Strategies, 1996) notes problems of funding for biological psychology due in part to ‘The inadequacy of classifying psychology for funding purposes as a social science, and thus not recognising explicitly its essence as a behavioural science, or its crucial biological science aspect …’ (p. 8).

Fields of Psychology as a Science

Some fields of psychology are defined in terms of the phenomena investigated, such as child psychology and learning theory, and this book contains many chapters devoted to such subject matter specialties. Other fields are defined in terms of the approaches or methods used, such as general psychology versus the study of individual differences, or basic research versus applied psychology. Let us consider a few such fields here, and they will be exemplified in several of the following chapters.

The study of general psychology is often contrasted with the study of individual differences. General psychology seeks to find principles and rules that apply to all people or members of a species, and we will see examples in such chapters as Chapter 5 on Perception and Chapter 7 on Memory. The study of individual differences emphasizes relatively persistent differences in the structure of behavior among persons or members of the same species; we will see examples in Chapter 16 on Personality and Individual Differences.

We saw above that psychology is sometimes classified as a biological science and sometimes as a social science. Similarly, within psychology the fields of biological psychology and social psychology are distinguished. Biological psychology, formerly called physiological psychology, is concerned with the relationships between biological processes, on the one hand, and behavior and mental processes, on the other. This approach will be examined in Chapter 4. Social psychology studies interactions within and among groups and the ways in which individuals influence or respond to each other. The social/societal bases of behavior are examined in Chapter 3.

Social psychology in turn is sometimes contrasted with cross-cultural psychology. Rather than assuming that social interactions and influences are invariant among all cultures, cross-cultural psychology examines to what extent they are the same and to what extent they differ. This approach is examined in Chapter 14. Beyond this, some psychological researchers emphasize that psychology itself is a social product, and there are active attempts to indigenize psychology, that is, to develop variants of psychology that are especially appropriate to specific societies and cultures or that will consider or incorporate implicit knowledge about human nature as it has developed in a society’ system of traditions, beliefs, and values. Although indigenization has become a rather popular concept, several recent analyses have been critical of indigenization as a goal, as Adair and Kagitcibasi (1995) have discussed. Kagitcibasi (1992) favors an orientation or methodology oriented towards discovering indigenous reality, but she questions indigenization as a goal. The topic of indigenization of psychology is discussed in Chapter 18.

Basic psychology is sometimes contrasted with applied psychology, the former being concerned with discovering facts and laws of psychology and the latter with applying psychological principles, methods and knowledge to practical situations. Some writers consider theoretical psychology as yet another, distinct field of psychological science (see Section 1.5 below and Chapter 26). Although many psychologists devote their efforts principally to one or the other of these poles of activity, it is now widely accepted that basic research has often been inspired by practical observations and problems, and that attempts at application can provide important tests of the adequacy of psychological hypotheses and further theoretical developments. Therefore there is much communication and interaction between those who do basic research and those who apply psychological knowledge and principles. Many of the following chapters present not only basic research but also its applications in the various areas of psychology.

Human Behavior as a Shared Object of Study

There are several other sciences that also have human behavior or aspects of it as their object of study. They can be clustered into three groups, depending on whether they follow a biological-medical, a social, or a predominately applied approach. In this section these ‘correlated’ sciences are briefly introduced, with an aim towards defining the specifics of psychology and its contributions as a science.

Correlated Biological-Medical Sciences

Though rooted conceptually in seventeenth to eighteenth-century philosophy, empirical psychology as an academic discipline grew out of physiology. Building on seminal contributions to the study of human perception by physiologists like Johannes Müller and Hermann Helmholtz, many first-generation university professors of psychology actually entered psychology after graduate study of medicine or physiology. Famous examples are Wilhelm Wundt (1843-1920), founder of the first University Laboratory of Psychology (1875) at the University of Leipzig, Germany, or William James (1842-1910) at Harvard University, USA, a founding father of empirical psychology in America. Close ties between physiology and psychology were typical not only in the founding years of academic psychology but continued ever since and now undergo an influential revival in modern neuroscience.

How can one differentiate between physiology and psychology? A common definition explains physiology as that ‘branch of biology that deals with functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved’ (Merriam-Webster, 1983, p. 888). By contrast, psychology is commonly defined as the science of behavior and experience, its causes and consequences (effects). To the extent that one can gain knowledge about behavior and conscious experience by investigating correlated functions of living matter, like the central nervous system, physiology and psychology share a common object of study. At the same time they typically differ in study approach, with physiologists preferring to work ‘upwards’, from living ‘organs’ tissue towards behavior, whereas psychologists prefer working ‘downwards’, from complex behavioral data towards their biological roots. While both sciences must cooperate, especially in methodological terms, they maintain their independence, also as a safeguard against undue biological reductionism (in psychology) or undue mentalism (in physiology).

Similar relations hold between psychology and other biomedical specialties such as neuro-physiology (physiology of the nervous system), endocrinology (physiology of endocrine glands), immunology (physiology of the immune system), genetics (science of hereditary bases of organismic variations), and human biology (also called anthropology by non-American authors and including the study of phylogenetic evolution of modern humans). Chapter 4 discusses these biological bases of human behavior and experience, while specifics of the biology of learning, perception, language behavior, emotion, and motivation are dealt with in the respective specialized chapters.

In research and in professional terms, psychology interfaces with the medical sciences both in clinical contexts and in the health sector at large, that is, in the assessment, prevention or therapy of psychological causes and effects of illnesses and diseases and in broader health-related issues, like health education. This holds especially for a field as interdisciplinary as mental health, where psychology and psychiatry (the clinical science of mental disorders) join force in investigating and treating mental disorders. Other examples of cross-disciplinary cooperation between psychology and medicine involve neurology (in the study and treatment of psychological disorders resulting from nervous system diseases and injuries), pediatrics (e.g., in children born prematurely), gerontology (in psychological care for the aged), and in all clinical disciplines (like gynecology) that involve intensive-care programs or deal with cancer and other severe forms of illness. Clinical and health psychology, psychopathology, neuropsychology, psycho-somatics, and medical psychology are specialties developed in these contexts. They are covered in Chapters 21 and 22 (Clinical Psychology) and in Chapter 23 (Health Psychology).

A concept sometimes confused with psychology is psychoanalysis. The latter refers to a specific theoretical and therapeutic approach in studying and treating behavior disorders, mainly of the so-called neurotic type such as anxiety disorders or obsessive-compulsive disorders. Founded by the Viennese psychiatrist Sigmund Freud (1856-1939) around the end of the nineteenth century, psychoanalysis is based on the general notion that non-conscious processes play an important role in shaping a person’ personality and, in case of unresolved conflicts, in the possible development of behavior disorders. Inaccessible in principle to direct observation, unconscious mechanisms are inferred from dream-content analysis, from a patient’ verbal reports while under hypnosis, or in the course of (usually long-term) therapeutic interventions. Psychoanalysis developed into a school of thought of its own, with varying degrees of input to and from academic psychology in different countries. Today psychoanalytic therapy is but one of several methodologies of psychotherapy, some of them often more effective than psychoanalysis in terms of costs and outcome (see Chapter 22).

Correlated Social Sciences

The ancient Greek philosopher and founder of speculative-philosophical psychology, Aristotle (384-322 B.C.E.), is quoted for the programmatic statement ‘ho ánthropos zõon politikón estin’, or ‘the human is a social being’ (Aristotle, Politeia). True enough, the content of human behavior and its development cannot be described, let alone explained, without reference to the social system of which any one of us is a member and to which each of us contributes. The basics of this social context of human behavior are presented in Chapters 3 and 16, while specific social interactions in perception, learning, etc. come up in the respective topical chapters.

How does psychology’ contribution to the study of human behavior differ from that of other social sciences, in particular sociology, political science, and economics? Sociology, the science of society, of social institutions and of social relationships, studies human behavior as part of these wider, collective structures and processes. By contrast, psychologists typically take off from the level of the individual. Often the two directions of study will prove complementary, for example in the study of social attitudes or in small-group research. By contrast, political science concentrates on the description and analysis of political (governmental and nongovernmental) institutions and processes and on structures of political action. Again there is overlap with psychology, as in the study of voting behavior or of interactions between government institutions and the individual. Finally, economics is the social science chiefly concerned with the study of the production, distribution and consumption of goods and services. Although this ties in closely with many facets of human behavior and with personal and collective values and preferences, cross-disciplinary cooperation between economics and psychology still leaves much to be desired.

Other social sciences correlated with psychology one way or another include ethnology (the description and analysis of behavior in its variations within and between cultures), human or social geography (the study of human behavior from a geographic-regional perspective), demography (the science of human population development), and public opinion research. Links and relationships between psychology and other social sciences are discussed in detail in Chapters 3, 27, and 31.

Psychological Methodology

The methods of psychological science are dealt with in detail in Chapter 2. They enable psychologists to gain knowledge about human behavior and conscious experience by systematic observation and experiment and to investigate, on the basis of such data, variations, dependencies, causes, correlates, and consequences of human behavior. In this way empirical generalizations become feasible and descriptive laws of behavior can be deduced and tested.

One important distinction in psychological methodology relates to the objectivity versus subjectivity of a method, that is, the degree to which its application and results prove independent of the persons applying the method, their explicit or implicit expectations, beliefs, or values. In the development of psychological methods over the past one hundred years, increasingly higher standards of objectivity and reliability have been achieved. Special methods like tests and questionnaires have been developed for the psychological assessment of individual differences in behavior (see Chapter 19). In addition, methods have been adapted from applied mathematics, numerical analysis, and statistics for the design of experiments, for behavioral measurement (scaling), descriptive data analysis (descriptive statistics), and for testing hypotheses (statistical inference). Depending on the kind of behavior under study, the data collected may be quantitative (numerical, like reaction-time measures) or categorical (qualitative, such as a client’ narration in a clinical interview or a psychotherapy session). Different methods of analysis have been developed for quantitative and qualitative behavioral data. Since the 1960s, electronic computing facilities have come to play a growing role in psychological methodology, first only for (statistical) data analysis, then also in data acquisition and, more recently, in data condensation (for example, in multivariate personality research or in psychophysiology). Today, personal computers have become indispensable tools for psychologists, and special software has been developed for computer-assisted psychological data-acquisition, data-storage, and data-analysis, both in research and for practical-professional work as in psychological assessment and testing (see Chapters 2 and 19).

Varieties and Criteria of Psychological Methodology

Methods of psychological observation, experimentation and data analysis vary with the kind of behavior and the type of question studied. In experimental research, measures of behavior are investigated as a function of one or several experimental independent variable(s). For example, an investigator may study how the speed of learning a new psychomotor coordination task will depend on the pacing of learning trials or the kind of feedback offered to subjects. In the design of an experiment the choice of independent variables is determined by the hypotheses derived from the theory guiding the study.

By contrast, in survey research, psychological phenomena are investigated with respect to variations accessible through a subject sampling plan. For example, a sample of 120 sixth-graders may be assessed in tests of school motivation and in a questionnaire of self-reported parental support in order to study correlations between these two sets of variables. In this case ‘natural’ sources of variation (between families, social classes, etc.) are studied, which are beyond the investigator’ control.

Cronbach (1957) has referred to these two types of methodology as experimental versus correlational psychology. They have one aspect in common: behavioral data are collected under standardized conditions. In contrast, in so-called field studies, data collection is devised so that it can take place in a person’ natural environment, at home, at work, in leisure settings or in other situations, as required by a study design. In recent years, further development of portable computer-based methods for psychological and psychophysiological data acquisition have become immensely helpful in building up genuine field research in psychology (Pawlik, 1998).

Psychological methods must meet stringent methodological, especially psychometric, criteria to be considered adequate in scientific-professional terms. They are discussed at length in Chapters 2 and 19 and include, in addition to objectivity, standards of reliability (percentage of variance in the data attributable to ‘true’ sources of variation, as compared with accidental or ‘error’ variance) and validity (degree to which observed variations are due to the intended component of behavior and only to this component). Other quality standards of psychological methods refer, for example, to the sensitivity of a method and its culture-fairness (freedom from sub-population bias).

Ethics of Psychological Investigations

Next to standards of methodology, psychological research both with human and nonhuman participants (or ‘subjects’, as they were called in earlier literature) must also meet criteria of professional ethics. They are included in the codes of ethics devised by the psychological associations of many countries. Some may even be part of the legal codes in a country.

In research with human participants, the principle of informed consent is considered indispensable (with only few and special exceptions as in orderly penal procedure). Informed consent is a guiding principle in national professional codes of ethics for psychology (Leach & Harbin, 1997). It maintains that participants in a study or an assessment must be informed in advance as to the purpose and methods of that study or assessment and the use to be made of its results. On the basis of this information, opportunity must be granted to voluntarily decline participation. Special rules of research ethics have been developed for research with handicapped persons and for clinical therapy research. In psychological assessment, testing, and counseling or therapy, psychologists are committed to assure strict confidentiality of results as related to concrete individuals. In Germany, for example, the penal code explicitly refers to psychologists, like doctors, attorneys or clergy, as being bound by the rule of personal confidentiality.

Many countries have passed laws concerning the use of animals in research, especially research involving pain or stress. Typically, regulations differentiate between species (for example, vertebrates versus non-vertebrates, with especially strict regulations for work with non-human primates) and include rules for animal care (housing, feeding, etc.).

Today in many countries funding agencies, universities and other institutions for psychological research have set up ethics committees to guide researchers and agencies in the preparation of research proposals and in granting decisions.

Theoretical Psychology

Theory development in psychology and a review of major theoretical systems in psychology are taken up in Chapter 29. A psychological theory is a system of statements, any one logically non-contradictory to all other statements in that same theory, which are developed (constructed) so as to account for a large number or range of phenomena in terms of fewer concepts (constructs), principles, or processes. In this way theories are parsimonious (‘reductive’ in the good sense of the word) and allow representation of many phenomena as a function of fewer theoretical terms. In a broad sense, these theoretical constructs, principles or processes are then said to explain the phenomena under consideration. Chapter 29 discusses alternative approaches to theory construction in psychology.

For example, a theory of anxiety disorders will attempt to explain the development of fear and of fear-responsive behavior on the basis of a few basic principles of learning and emotion (see, for example, Gray, 1982). In order for such a theory to be testable, it is indispensable that each term (concept, principle, or process) used in a statement be linked to relevant observables, that is, to operations of behavior observation. If a theory does not fulfill the requirement of operational definition, it will prove logically impossible to devise a test of its appropriateness in a way that can not immediately be declared improper by simply changing definitions of terms! Equally obvious, no matter how appropriate a theory may appear today for a given set of phenomena, new evidence tomorrow may change the picture or even disprove the theory. In psychology this has happened more than once. For example, the theory of general intelligence developed by Charles Spearman in the early twentieth century (Spearman, 1904), seemingly in good accord with then available evidence on intelligence test intercorrelations, was soon questioned by Cyril Burt and finally disproved empirically in 1934 by L. L. Thurstone (see Wolman, 1985, for a synoptic review).

It is this notion of relativity of scientific theories that led the Austrian-British philosopher Karl R. Popper (1974) to emphasize that the truthfulness of a theory can never be proven (in the full sense of the word); instead theories can only, and at best, be shown not to be in conflict with data at hand, that is, be non-falsifiable for the time being. Methods and criteria for theory testing constitute a classical topic of epistemology and have been dealt with extensively in modern analytical philosophy (see, for example, Lenk, 1975). Popper’ falsifiability criterion has not remained undisputed, still most research in psychology has been guided by it, in addition to the criterion of replicability of a finding, that is, its independent confirmation by other researchers and in other laboratories.

In this Handbook pertinent theories of human behavior, of development and of mental functioning are reviewed in the respective chapters, most notably in Chapters 5-18.

History of Psychological Science

Standard histories of psychology have mainly been written from the viewpoints of Western Europe or North America, but the history of psychology has varied among different countries and regions of the world, as is reflected in some recent books (e.g., Gilgen & Gilgen, 1987; Sexton & Hogan, 1992) and symposia (e.g., Adair & Kagitcibasi, 1995; Pawlik & Rosenzweig, 1994). In every region of the world, systems of thought were concerned with human experience and behavior. Modern scientific psychology began in the German-speaking countries after the middle of the nineteenth century, and rapidly spread to North America, but it reached many developing areas of the world only after World War II.

In Europe and North America psychology developed from both philosophy and physiology, and from other disciplines as well. As Mueller (1979) noted, several lines of research that antedated psychology all led into the development of psychology in Europe and North America. These included the following lines:

Work on sensation and perception by physicists and biologists such as Newton, Young, Fechner, Helmholtz, and Wundt;
Work on localization of psychological functions in the nervous system by physiologists such as Bell and Magendie, Sechenov, Fritsch and Hitzig, and Hughlings Jackson;
Sociomedical work by investigators such as Pinel, Charcot, Freud, and early workers on mental testing such as Binet and Ebbinghaus;
Materialistic attempts to reduce life processes to chemistry and biology in the work of such scientists as Loeb and Jennings;
Darwin’ theory of evolution. This was congenial to and fostered the American interests in individual differences (the variation that makes natural selection possible). It also made the study of animal behavior appropriate as a pathway to the understanding of human beings, and it made the development of comparative psychology reasonable.

At the same time that psychology was evolving from a philosophical to a scientific enterprise in the latter half of the nineteenth century, this evolution was also favored by a transition in the organization of colleges and universities in many industrialized countries from strictly undergraduate institutions to organizations that included, and often specialized in, postgraduate education.

The growth of psychology was also fostered by the organization of courses, laboratories, scientific associations, journals, and congresses. In this regard, the development of psychology paralleled that of other sciences in the developed countries. Courses in psychology in the United States evolved from courses with such names as ‘Intellectual Philosophy’, ‘Mental Philosophy’, and ‘Mental Science’ that were taught in American colleges in the first half of the nineteenth century. Textbooks for such courses began to use the term ‘psychology’ in their titles by the 1830-40s, but courses entitled psychology became popular only in the 1870-80s. Large numbers of colleges were founded in the US by various churches, and later most of these became non-denominational. The formation of state universities was promoted by grants from the federal government. In the last third of the nineteenth century, the philanthropy of several wealthy individuals led to the founding of private universities with an emphasis on research and graduate studies. The widespread philanthropic support of American institutions of higher education is characteristic of the American scene and differentiates it from most other countries. Graduate programs in psychology soon emerged. In 1875 G. Stanley Hall received what was perhaps the world’ first PhD degree in psychology from Harvard for work done with William James.

Laboratories were early seen to be necessary to pursue psychology in the Fechnerian-Wundtian tradition. The first laboratory of experimental psychology was established 1875 by Wilhelm Wundt at the University of Leipzig, to be followed in the German-speaking countries by the founding of institutes of psychology at the Universities of Bonn, Graz, and Kiel in the 1890s. Chapter 30 provides some comparative information on the development of psychology in different countries. By 1892, about 20 American colleges and universities had laboratories of psychology. As of 1900, laboratories of psychology had been founded at 41 US colleges and universities, more than in all the rest of the world.

Almost from the start of modern psychological research, investigators from different laboratories and institutions have met to discuss their research. This soon led to formation of local, then national, and international organizations to foster such meetings and encourage research. The world’ oldest national psychological association is the American Psychological Association (APA), founded in 1892. This was part of the movement to establish disciplinary societies in the US, starting with the American Chemical Society in 1876. National psychological organizations were formed in France and in the United Kingdom in 1901, in Germany in 1904, in Argentina in 1908, and in Italy in 1910. For dates of formation of other national psychological organizations, see Table 30.1 in Chapter 30. In many developing countries, national psychological associations were formed only in the 1950s or even later.

By 1881 psychologists were discussing the need for an international meeting, and the first International Congress of Psychology took place in Paris in 1889. Subsequent International Congresses of Psychology have taken place every three to five years, with gaps caused by the two World Wars. Since 1951 these congresses have been organized by the IUPsyS, and since 1972 they have taken place every four years. The International Congresses of Psychology at Leipzig (1980), Acapulco (1984), Sydney (1988), Brussels (1992), and Montreal (1996) have each attracted about 4,000 participants. (For a history of the International Congresses of Psychology and the IUPsyS, see Rosenzweig, Holtzman, Sabourin and Belanger, 2000.) The 27th International Congress of Psychology takes place in Stockholm in 2000, and the 28th Congress is scheduled for Beijing in 2004.

Throughout its history, psychology has been shaped also by social events and movements. For example, the two World Wars had major effects on the development of psychology. In World War I, psychologists were active in testing and classifying recruits. This stimulated further applications of psychology in different fields also in the postwar years. During World War I, the annual number of psychological publications in German fell below those in English, and thereafter English maintained its predominance. In World War II, psychologists also aided in designing equipment, in preparing training materials and in giving psychotherapy to members of the armed forces. In the United States, the postwar years saw a tremendous expansion of psychology. Many returning soldiers went to colleges and universities on government scholarships, fostering the growth of academic psychology. Also, the government subsidized graduate programs, especially in clinical psychology, to aid in caring for veterans with psychological problems. Across the Atlantic Ocean, in Austria and Germany the terror regime of the Nazis and the war brought psychological research almost to an absolute halt (Pawlik, 1994b); it took more than a decade to succeed gradually in re-establishing a psychological university education after the war. On the other hand, World War II weakened the colonial powers, leading to independence of many Asian and African countries; this in turn strengthened the movement toward development of indigenous psychologies, relevant to different cultural contexts. All throughout its history, the development of psychology proved particularly sensitive to infringements of personal freedom and civil rights as has been shown, for example, by Jing (1994, and Chapter 30) for the so-called Cultural Revolution and its effects on the state of psychology in China.

Psychology around the World: International Distribution of Psychologists and Psychological Organizations

International Distribution of Psychologists

The number of psychologists in the world has been increasing rapidly in the last decades. An estimate made for 1980 showed about 260,000 (Rosenzweig, 1982). By 1991 the total probably reached 500,000 according the 1991 IUPsyS survey (Rosenzweig, 1992), indicating approximately a doubling over a decade. By 2000, the total is undoubtedly close to one million.

In making these estimates, local definitions of ‘psychologist’ were used; that is, the numbers include those who are considered to be qualified to call themselves psychologists in each country. The amount of training for this differs greatly among countries. In the United States and Canada, most psychologists have a doctoral degree, and the others have master’ degrees. In many other countries, four or five years of postsecondary education suffice, and in some countries as little as three years of postsecondary training are considered sufficient.

To put the worldwide number of psychologists into perspective, Rosenzweig (1992, pp. 19-21) compared it with the numbers of physicians and of neuroscientists, because the work of the latter groups parallels that of certain main groups of psychologists: those who provide health-services and those who are engaged in research and academic work. It appeared that in 1992 the total number of psychologists was about one twelfth the number of physicians in the world but about twenty times the number of neuro-scientists.

Psychologists are distributed very unequally around the world. In the 1991 IUPsyS survey, the number of psychologists per million population was 550 in 11 industrialized countries outside of Eastern Europe, 83/million in four countries of Eastern Europe, 191/million in 14 developing countries outside of China, and 2.4/million in China. The numbers of psychologists engaged in research showed even greater inequality of distribution: 23/million in 15 industrialized countries and only 4.2/million in 15 developing countries.

The ratios of female to male psychologists in main regions of the world are summarized by Sexton and Hogan (1992, pp. 469-470) as follows. In European countries, 53% of all psychologists are women, in South American and Caribbean countries, 70% are women, but overall in Asian countries only 25% are women, although some Asian countries have high percentages of women. In the United States the percentage of doctorate degrees going to women had risen to 58% by 1990. Among these doctorates, the ratio of women to men was clearly larger in the areas of educational (2.38), developmental (2.36), school (1.89), social (1.74), counseling (1.52), and clinical psychology (1.42); these areas where women predominate in the US include all of the health-provider fields but are not limited to them. The ratio of women to men obtaining doctorates in the US in 1990 was lowest in experimental (0.52) and industrial/ organizational (0.75) psychology.

International Distribution of Psychological Organizations

Psychologists have formed many national, regional, and international psychological organizations, as well as organizations for specialized fields of psychology. Figure 1.1 shows some of these psychological organizations, as well as relations to some international bodies. In 1892 the first still-existing national psychological organization was formed—the American Psychological Association. As of mid-1999, 66 national organizations belong to the International Union of Psychological Science (IUPsyS), and more are joining every year. The IUPsyS traces its history back to the international committee that organized International Congresses of Psychology, after the first such Congress in Paris in 1889. There are also regional organizations, such as the Interamerican Society of Psychology (Sociedad Interamericana de Psicologia) or the Association de Psychologie Scientifique de Langue Française.

Among the international associations with individual memberships, the largest is the International Association for Applied Psychology (IAAP), founded in 1920. The IAAP and 10 other international organizations are affiliated with the IUPsyS.

The psychological organizations with individual members vary enormously in size, the largest being the American Psychological Association with about 87,000 full members as of 1999. These organizations perform many important functions, including holding regular scientific and professional meetings to help their members keep up-to-date on advances in their fields; publishing scientific and professional journals; helping to inform the public about psychological matters; striving for legislation to improve support for education, research, and professional representation; and cooperating with scientific and professional organizations of related disciplines.

Psychology as a Profession

If members of the public are asked what work psychologists do, some will reply that they conduct psychotherapy with individual clients and others will say that they teach in colleges and universities. These answers are correct as far as they go, but they do not begin to suggest, let alone encompass the wide variety of occupations psychologists perform or the variety of their workplaces. Let us consider some of the variety of psychologists’ occupations, drawing some of the following material from a publication of the American Psychological Association (APA) that takes up this topic at greater length than we can here (Psychology/Careers for the twenty-first century: Scientific problem solvers).

Many psychologists conduct research as their primary or secondary occupation. Some of this research takes place in laboratories where experimental conditions can be carefully controlled. Much of this laboratory research is conducted in universities, government agencies, and private organizations such as pharmaceutical firms. Some psychological research is carried out in the field, in offices and factories, public places, schools, and hospitals, where behavior is observed and recorded as it occurs naturally. Here psychologists study and contribute to the work environment, partly in what is called industrial/ organizational or personnel psychology. As the APA publication notes:

Psychologists study what makes people effective, satisfied, and motivated in their jobs; what distinguishes good workers or managers from poor ones; and what conditions of work promote high or low productivity, morale, and safety.

Some psychologists design programs for recruiting, selecting, placing, and training employees. They help make changes in the way the organization is set up.

Others help design the actual tasks, tools, and environments with which people must deal when doing their jobs. These specialists can also help design the products that organizations turn out and conduct research related to product design. For example, they play a big role in making computer hardware more user-friendly, which in turn contributes to both to operator performance in the workplace and product acceptability in the marketplace.

Psychologists with training in mental health and health care also deal with the health and adjustment of individuals in the work setting. They work with employee assistance plans that provide help with drug or alcohol addiction problems; they also foster healthy behavior. (American Psychological Association, 1996, p. 17)

Organizational/industrial psychologists work for private companies or in governmental agencies. Some have set up their own consulting firms. Still other psychologists work to promote physical and mental health. In some countries, many of these psychologists have a private practice, with clients and patients coming to the psychologist’ office. In other countries, most health psychologists work in governmental agencies. According to the APA publication:

Increasingly, … psychologists in independent practice are contracting on either a part-time or full-time basis with organizations to provide a wide range of services. For example, a psychologist can join a health practice and work with a team of other health care providers, such as physicians, nutritionists, physiotherapists, and social workers to prevent or treat illness …

Psychologists also instruct students who are training to become health care professionals, such as physicians and nurses, about psychological factors involved in illness. And they advise health care providers already in practice about the psychological bases of much illness so that symptoms that are psychological in origin can be better diagnosed and treated. Psychologists involved in health care teams typically work in hospitals, medical schools, outpatient clinics, nursing home, pain clinics, rehabilitation facilities, and community health and mental health centers. (American Psychological Association, 1996, p. 19)

Organization of Study in Psychology

Academic and professional training in psychology vary, at times to a surprising degree, among universities and, still more so, among countries and regions; they also vary depending on institutional structures of higher education. In the present context only a brief summary presentation is feasible. We shall first look at the organization of study in industrialized countries.

One-Level versus Two-Level Study

Universities organized in the British College tradition—that is in Australia, North America and in the United Kingdom—still adhere to the two-level structure of separate undergraduate and graduate schools, whereas universities in most Continental European countries follow a one-level, continuous organization. Such structural differences in higher-education institutions also relate to differences in pre-university (secondary or high school-level) education in the respective countries and they have consequences, among others, for the organization of an academic curriculum. In the one-level structure, introductory (undergraduate) and advanced (graduate) curriculum components are organized within one and the same school, usually with significant and flexible interplay between the two.

A recent survey by Newstead and Makinen (1997) illustrates this point. They compared university training schedules in psychology from a survey conducted by the European Federation of Professional Psychologists’ Associations and from additional reports obtained from 14 European countries. They found that 15 countries offer a one-level course in psychology and only five countries follow a two-level model of teaching. One implication of a one-level program is that almost all students completing the first years of study in psychology attempt to continue and complete the full course. This is different from the situation, for example, in the US where admission to graduate school is contingent upon a new selection procedure and by no means automatic after graduation from college with a major in psychology. As a result, significant numbers of students in the US complete an undergraduate program in psychology without continuing for graduate training in psychology. The design of an undergraduate program in psychology takes this into account. By contrast, the one-level program is oriented towards full-scale study in psychology from the first semester onwards.

Generalist versus Specialist Training Philosophy

The survey by Newstead and Makinen (1997) also highlights another source of variation in psychology course design: the difference between a generalist and a specialist training philosophy. Among European countries, the generalist model is followed in 12 countries. Notwithstanding some specialization among applied fields, typically in the last 2 years of a 5-year course, students are trained to acquire proficiency in all major fields of psychology and prepare for a wide sector, if not the full range of professional psychological activities. This is in marked contrast to the typical North American program which requires the student to choose one, often relatively narrow, field of specialization from the first or second graduate year onwards. While a generalist curriculum design emphasizes breadth of competence at the expense of possibly too early in-depth specialization, the specialist curriculum design builds on exemplary high competence in one or a few fields, at the necessary expense of overview and transfer of knowledge across fields. The relative merits and shortcomings of either model still await detailed analysis; quite likely, they will vary also with differences in the economic and educational state of development of a country.

Scientific-Academic versus Professional Training

By their tradition, universities strive for the highest scientific-academic standards of training. By the late 1960s in North America and about a decade later in Europe, this training philosophy was more and more challenged by growing demands for psychological practitioners prepared to enter professional work in schools and clinics, in private practice, in industry, etc. Different universities and countries reacted differently to this challenge. In North America, a new type of tertiary education institution came into existence: the Professional Schools of Psychology, no longer offering a research degree but a professional doctorate like the doctor of psychology (Psy.D.). At the same time, highranking university departments of psychology began to introduce comparable course programs, often also leading to a Psy.D. degree, many of them following the science-practitioner or Boulder model of the APA. As a rule, these programs contain an obligatory half- to one-year practical internship. In recent years similar specialized science-practitioner curricula have also been set up at some British universities.

In countries adhering to the one-level, generalist model of education in psychology, growing specialization and professionalization has recently given rise to a new kind of two-stage model of training, which assigns the professional-practical teaching to a postgraduate science-practitioner course in psychology. In Germany, for example, a federal law passed in 1998 requires psychology graduates after completion of the 5- to 6-year university course in psychology to enroll in a subsequent 3-year postgraduate training which will prepare them for a state examination (‘approbation’) pre-requisite for professional psychotherapeutic work. Such postgraduate programs combine advanced, specialized scientific and practical on-the-job training; they are organized by university departments in cooperation with practical-professional institutions like psychiatric or neurological hospitals, day-care centers, etc. Trainees are expected to hold a supervised part-time position in the respective field. The merits and likely shortcomings of such two-stage training models still await evaluation.

Psychology Training outside North America and Europe

Today training in many countries outside North America and Europe resembles either the US-American or one of the European curricular plans, usually depending on historical ties in political-economic development. In Mexico, for example, students enroll in the psychology program immediately after completing high school with a baccalaureate degree, and training requires 5 to 6 years. Other Latin American countries follow a similar plan. In East African countries, the British model seems to prevail, whereas in West African countries it is the French type. Australia and New Zealand have programs similar to the US-American curriculum, as do Japan and China.

Sources of Information about Psychology

Each chapter of this Handbook gives some general Resource References, as well as specific references to certain points in the chapter. The general references will help the interested reader to find more about the topic.

Like other sciences, psychology offers a broad spectrum of information sources, ranging from traditional forms such as books, monographs, and journals to the modern-technology information access via the Internet. In the early days of experimental psychology, psychological research was published in journals of philosophy or physiology. The first journals specifically devoted to psychology began to appear in the last quarter of the nineteenth century, among them such distinguished periodicals as the German-language journals Archiv für Psychologie (started in 1875) and Zeitschrift für Psychologie (started in 1885), the American Journal of Psychology (started in 1888), and L Année Psychologique (started in 1895). With the exception of the Archiv für Psychologie, they all still continue in publication. In the early 1900s, psychological journals began to differentiate and multiply rapidly. According to a recent estimate (literature database PsycINFO, American Psychological Association) the world-wide total number of high-quality, peer-reviewed psychological or psychology-related journals is around 1,500; almost 17% of these are non-English language publications. Psychology journals differ in topical breadth, ranging from broad, general journals, addressing all fields of psychology, to more and more specialized journals (e.g., cognitive psychology, methods of psychological assessment or therapy). They also differ in regional coverage, from global journals (such as the International Journal of Psychology and the International Journal of Applied Psychology), through regional journals (such as the American Psychologist, the European Psychologist, and the Scandinavian Journal of Psychology), to primarily national journals (such as the Russian Voprosi Psykhologi, the Rivista Mexicana de Psicologia, or the Indian Journal of Social Psychology). And they vary in journal profile as to scientific research or professional-practical orientation.

Today English has become the major, global communication language, in psychology as in other fields. However, about 5% of journal publications in the PsycINFO database still appear in a language other than English. (This percentage is smaller than that of non-English journals partly because English-language journals tend to be published more frequently and to contain more articles per issue than do non-English language journals.) In the number of journal articles published per year, the major non-English languages of publication in psychology are German (with 1.54% of articles in the PsycINFO database), French (1.26%), Spanish (1.20%), Japanese (0.75%), Chinese (0.37%), and Russian (0.22%). In recent years there is growing trend towards usage of the English language even in publications from non-Anglophone countries. Maintaining sufficient accessibility of the so-called non-English-language or NEL literature has been of continuing concern to the International Union of Psychological Science. At the time of writing, there is a tendency for psychological NEL journals of basic research to gradually change towards an all-English format whereas professional journals serving psychological practitioners are more likely to stick to their national-language format.

Inevitably, NEL journal publications entail narrower limits in availability and accessibility of a contribution across countries and language areas. On the other hand, turning every psychological publication into English would involve the risk of alienating the language of psychology from the natural language of the people in a country. In addition, it would set higher thresholds for authors less fluent in English. The language issue becomes especially critical for introductory texts for schools and universities. The prevailing tendency in many NEL regions is to use the local language for introductory texts. As a result, the psychological textbook literature has seen a plethora of textbook translations since the 1950s. Foundations have even made special grants to support the translation of leading texts and resource books into languages (such as Chinese, Russian) which serve large regions of the world that otherwise have reduced access to psychological literature.

The rapid increase in number of annual publications in psychological science impelled psychologists, as early as the 1890s, to devise reference publications to guide readers through this ever-growing literature. Annual lists of psychological publications were first published in the Zeitschrift fuer Psychologie und Physiologie der Sinnesorgane beginning with volume one, 1890. In 1895 L’nné e Psychologique published in its first volume a classified bibliography. This continued until 1905 when the service was expanded to provide abstracts of psychological publications. The American journal, Psychological Review, began in 1895 a separate publication, the Psychological Index, which listed psychological publications in 35 annual volumes until 1942, when it was merged into the Psychological Abstracts, started in 1927 by the American Psychological Association. Psychological Abstracts became the world-wide reference source for publications in psychology, appearing in its 74th volume in 2000. This journal publishes brief summaries of psychological book and journal publications, with full citations. Until 1988, Psychological Abstracts still aimed at world-wide coverage irrespective of the original language of a publication. With the continuing growth in number of annual publications in psychological science, the number of abstracts per Psychological Abstracts volume reached 33,000 by the mid-1980s. At that time, the APA set up the new abstract database, PsycINFO, which was accessible through online electronic networking (nowadays via internet service providers) and, soon thereafter, also off-line on CD-Rom (PsychLit). So starting 1988, the print version of Psychological Abstracts was limited to those abstracts from the PsycINFO database which came from Anglophone publications. It is expected (and already noticeable) that, with increasing accessibility of electronic database facilities, the printed version of Psychological Abstracts will steadily lose its importance. In addition to its wider coverage and prompt up-dating facility, PsycINFO also offers advanced means of automatic keyterm search analysis. Other electronic publication databases of relevance to psychology are Med-Line, the medical literature abstract database published by the U.S. National Library of Medicine, and a number of specialized literature databases in the neurosciences, in environmental sciences, and in the social sciences at large (Social Science Citation Index).

Another type of secondary source publication in psychology developed in the 1950s: topical reviews, summary reports, and, more recently, statistically refined so-called meta-analytic studies. Volume 1 of the Annual Review of Psychology appeared in 1950. Published by the Annual Review Corporation, USA, the 51st volume appeared in 2000. Other Annual Review publications of interest to psychology are those in anthropology, genetics, immunology, medicine, neuroscience, physiology, public health, and sociology. (Of the 27 Annual Review publications, the psychological review ranks fourth in initial year of publication.) The Annual Review of Psychology covers the different specialties of psychology according to a several-year publication schedule, with more important fields reviewed every second or third year, others at longer intervals. Additional reviews and summary articles on methods of psychological assessment are covered in a special bibliographic and review source publication, the Mental Measurement Yearbook, now also available via electronic on-line internet services.

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