Psychology

I

Introduction

Psychology, scientific study of behaviour and experience—that is, the study of how human beings and other species sense, think, learn, know, communicate and interact. Modern psychology is devoted to collecting facts about behaviour and experience and systematically organizing such facts into psychological theories. These theories aid in understanding and explaining people’s behaviour and sometimes in predicting and influencing their future actions.

Psychology, historically, has been divided into many subfields of study; these fields, however, are interrelated and frequently overlap. Physiological psychologists, for instance, study, among other things, the functioning of the brain and nervous system and the role of hormones in the endocrine system in behaviour; developmental psychologists are interested in the whole process of development, both physical and behavioural, from birth to old age. Social psychologists examine the ways in which people influence one another and the way they act in groups. Industrial psychologists study the behaviour of people at work and the effects of the work environment. Educational psychologists help students make educational and career decisions, and diagnose and treat those with learning difficulties. Clinical psychologists assist those who have problems in daily life or who are mentally ill.

II

History

The science of psychology developed from many diverse sources, but its origins as a science may be traced to ancient Greece.

A

Philosophical Beginnings

Plato and Aristotle, as well as other Greek philosophers, took up some of the basic questions of psychology that are still under study: those to do with whether people are born with certain skills, abilities, and personality, or whether these develop as a result of experience. They ask how people come to know the world and how we can account for the manifest differences between people.

Such questions were debated for many centuries, but the roots of modern psychological theory are found in the 17th century in the works of the French philosopher René Descartes and the British philosophers Thomas Hobbes and John Locke. Descartes argued that the bodies of people are like clockwork machines, but that their minds (or souls) are separate and unique. He maintained that minds have certain inborn, or innate, ideas and that these ideas are crucial in organizing people’s experiencing of the world. Hobbes and Locke, on the other hand, stressed the role of experience as the source of human knowledge. Locke believed that all information about the physical world comes through the senses and that all correct ideas can be traced to the sensory information on which they are based.

Most modern psychology developed along the lines of Locke’s view. Some European psychologists who studied perception, however, held on to Descartes’s idea that some mental organization is innate, and the concept still plays a role in theories of perception and cognition (thinking and reasoning). It is also seen in Noam Chomsky‘s theory of language, and in Carl Gustav Jung‘s more speculative theory of personality. More generally, current research is revealing in detail how much “nature” contributes to the causes of behaviour, as compared to “nurture”.

B

Scientific Developments

Against this philosophical background, the field that contributed most to the development of scientific psychology was physiology—the study of the functions of the various organ systems of the body. The German physiologist Johannes Müller tried to relate sensory experience both to events in the nervous system and to events in the organism’s physical environment. The first true exponents of experimental psychology were the German physicist Gustav Theodor Fechner and the German physiologist Wilhelm Wundt. Fechner developed experimental methods for measuring sensations in terms of the physical magnitude of the stimuli producing them. Wundt, who in Leipzig, Germany, in 1879 founded the first laboratory of experimental psychology, trained students from around the world in the new science.

This experimental tradition rested on the assumption that the basic mechanisms and units of behaviour could be identified, in a way analogous to the physical sciences. Human beings, however, are essentially individuals, differing from each other in important ways. The scientific measurement of individual differences (psychometrics) can be said to take as its starting point the work of Francis Galton, in particular his book Hereditary Genius (1869). He also showed how, in principle, the origins of these differences could be traced to the relative effects of heredity and environment.

Medical practitioners who became concerned with mental illness also contributed to the development of modern psychological theories. Thus, the systematic classification of mental disorders developed by the German psychiatric pioneer Emil Kraepelin, which was the original method of classification, is still in use. Far better known, however, is the work of Sigmund Freud, who devised the system of investigation and treatment known as psychoanalysis. Freud called attention to instinctual drives and unconscious motivational processes that determine people’s behaviour. His stress on the dynamics of behaviour—that is, what makes people do things—and on the importance of early childhood, exerted a strong influence on the course of modern psychology, although most of his detailed theories have not been well supported by later research.