This article describes current work in selective attention within a framework derived from important findings extending back over a century. The contributions of Danders, Helmholtz, Pavlov, Sokolov, and Wundt, for example, are deeply embedded in current methods for studying selectivity. The cumulative nature of work on attention is not widely appreciated, in part because of a failure to recognize that the methods used in current studies arose in empirical findings of the past and also because attention is a concept that can be studied at many levels. There is evidence that findings at the level of performance, subjective experience, and neural systems can be linked, even though they are not yet reducible to a single theory. Studies to date reveal some properties of a complex neural mechanism involved in our awareness of a stimulus. The time course of operation of this mechanism can be studied objectively and shown to be related both to changes in performance and to subjective experience. This attentional mechanism is involved in the skilled performance of daily life, but many other systems are also important in determining the degree to which natural tasks can be time shared. The goal of every science is a cumulative development of its theoretical structure so that a larger part of its subject matter is explicable in terms of simpler principles. This traditional view of science has been challenged in psychology from many sources. One argument has been that it is better to view psychology in terms of shifting paradigms (Kuhn, 1962). It often seems to be accepted, almost as a matter of course, that in psychology no cumulative development will take place. A different challenge to the view of psychology as a cumulative science is the notion that nothing new is discovered while the views of Helmholtz, Wundt, or some other elder of the field are being reworked, with no apparent gain in either insight or scope. These two challenges to the cumulative nature of psychological theory are persuasive, but they are hot consistent. If we shift from paradigm to paradigm, it seems puzzling that the current paradigm would so exactly mirror that of 100 years ago. On the other hand, if the solutions of 100 years ago remain, what has happened to paradigm shifts? Another criticism that has been applied to the 168 • FEBRUARY 1982 • AMERICAN PSYCHOLOGIST study of attention is that psychological theories are sterile, in that they do not illuminate important natural behavior or provide a perspective on the nature of mind (Neisser, 1976). The contention in this article is that one can see emerging from psychological research in the area of attention a cumulative development of theoretical concepts that rely on principles, some over 100 years old, that are now elaborated in ways that were essentially unavailable to earlier researchers. Moreover, taken as a whole these ideas do provide insight into the skills of daily life. If this contention is correct, why is it that the cumulative development of psychological theories of attention arfe so obscure, even to/ researchers in the field? I believe that several facts about the nature of psychological inquiry make its cumulative development obscure even to those who read the psychological literature. The first difficulty in perceiving the cumulative nature of theories arises because much work in psychology is fueled by tests between complex theoretical views that differ in only subtle ways. These theories often have common assumptions, but similarities between them that amount to a common core of agreed principles are overlooked. The view of experiments as tests among competing, wellspecified theories can be contrasted with the more cumulative theoretical approach outlined by Broadbent (1958): The proper road for progress then is to set up theories which are not at first detailed, although they must be capable of disproof. As research advances the theory will become continually more detailed, until one reaches the stage at which further advance is made by giving exact values to constants previously left unspecified in equaThis article was presented as a Distinguished Scientific Contribution Award address at the meeting of the' American Psychological Association, Los Angeles, September 1981. This work was supported by a series of National Science Foundation grants to the University of Oregon. I am most grateful to the many students and colleagues who have contributed to this work, and to Mary R'othbart for assistance in writing it. Requests for reprints should be sent to Michael I. Posner, Department of Psychology, University of Oregon, Eugene, Or-