Logical Positivism and Operationism

The abandonment of mind as psychology’s subject matter, the increased attention to ensuring that scientific standards were met by procedures for gathering and treating data in laboratory and nonlaboratory research, and increased attention to theory building appeared to be signs of scientific maturity in psychology. These characteristics were most closely identified with the neo-behaviorist theories of learning and behavior that were the focus of much of the laboratory psychology from the 1930s to the 1960s. These theories focused on animal subjects and models of learning and behavior; theirtheoretical language was influenced by a philosophy of
science of the period. Continuing concern for the scientific status of psychology
attracted psychologists to an approach to science advocated by Harvard physicist P. W. Bridgman (1927), who made the case for defining unobservable phenomena, such as gravity or hypothesized physical elements such as an electron, in terms of the operations by which their effects on observable events could be measured (Leahey, 2001; Smith, 1986). E. G. Boring’s student, S. S. Stevens (1906–1973), at Harvard in
psychology, proposed that psychology adopt a strict operationism (Stevens, 1935a, 1935b, 1939). Only terms that could be defined operationally were scientifically meaningful; for all practical purposes, only a behavioral psychology could meet this criterion (Leahey, 2001; J. A. Mills, 1998; Smith, 1986). The emphasis on operational definitions influenced the language of psychology (Mandler & Kessen, 1959) and the
theories of behavior that evolved in the context of operationism and its philosophical forebear, logical positivism, an approach that limited science to observable phenomena. For psychology, it meant defining hunger, for example, in terms of such operations as hours of food deprivation, or a measure of blood sugar level, or the amount of time spent eating, each of which is an observable indicator of the unobservable hypothesized motivational condition of hunger. The neo-behaviorists
who shaped what is known as the “Golden Age of Learning Theory” from 1930 to 1950 adopted some ideas from logical positivism and operationism, although each of them was to formulate his own vision of behaviorism (J. A. Mills, 1998; Smith, 1986).