BARRIERS BETWEEN THEORIES AND MECHANISMS1
In this chapter, I explore the problem of the role of theories and models in relating perceptual processes to the underlying mechanisms. I ask: What do formal models of cognitive or perceptual processes mean? What can models do and what can they not do? The purpose of this chapter is to consider these questions for a wide variety of formal models--mathematical, computational, neural network, statistical, symbolic, and others that are just arriving on the scene.
Formal models and theories have been with us for some time. Mathematics and statistics have been used to describe cognitive processes throughout the history of experimental psychology. Historically, the first theories in this science, those of Weber and Fechner, were both formulated in the language of algebra and calculus. Computer models have been with us from virtually the first moment that digital computer technology became available (see, e.g., Farley & Clark, 1954, Rosenblatt, 1962, Selfridge, 1958, and Widrow, 1962, among others; and for a comprehensive review of the history of this field and the mathematical relationships among the various theories see Grossberg, 1988a, and Carpenter and Grossberg, 1991). The Anderson and Rosenfeld ( 1988) and Anderson, Pellionisz,and Rosenfeld ( 1990) com-____________________