Implicit Learning and Tacit Knowledge

I examine the phenomenon of implicit learning, the process by which knowledge about the ralegoverned complexities of the stimulus environment is acquired independently of conscious attempts to do so. Our research with the two, seemingly disparate experimental paradigms of synthetic grammar learning and probability learning is reviewed and integrated with other approaches to the general problem of unconscious cognition. The conclusions reached are as follows: (a) Implicit learning produces a tacit knowledge base that is abstract and representative of the structure of the environment; (b) such knowledge is optimally acquired independently of conscious efforts to learn; and (c) it can be used implicitly to solve problems and make accurate decisions about novel stimulus circumstances. Various epistemological issues and related prob1 lems such as intuition, neuroclinical disorders of learning and memory, and the relationship of evolutionary processes to cognitive science are also discussed. Some two decades ago the term implicit learning was first used to characterize how one develops intuitive knowledge about the underlying structure of a complex stimulus environment (Reber, 1965, 1967). In those early writings, I argued that implicit learning is characterized by two critical features: (a) It is an unconscious process and (b) it yields abstract knowledge. Implicit knowledge results from the induction of an abstract representation of the structure that the stimulus environment displays, and this knowledge is acquired in the absence of conscious, reflective strategies to learn. Since then, the evidence in support of this theory has been abundant, and many of the details of the process have been sharpened. This article is an overview of this evidence and an attempt to extend the general concepts to provide some insight into a variety of related processes such as arriving at intuitive judgments, complex decision making, and, in a broad sense, learning about the complex covariations among events that characterize the environment. Put simply, this is an article about learning. It seems curious, given the pattern of psychological investigation of the middle decades of this century, that the topic of learning should be so poorly represented in the contemporary literature in cognitive psychology. The energies of cognitive scientists have been invested largely in the analysis and modeling of existing knowledge rather than in investigations of how it was acquired. For example, in an important recent article on the general topic of unconscious memorial systems, Schacter (1987) never came to grips with the distinction between implicit learning and implicit memory. The latter, the focus of his review, was dealt with historically, characterized, out