ABSTRACT
Cognitive scientists often compare the brain with a computer. Early writers (e.g., von Neuman, 1958) emphasized comparisons with both analog and digital computers, but as the use of analog computers declined, so did their role as a metaphor for the mind. Although the biological evidence is congenial to a computer metaphor, it does not exclusively favor digital or analog computing (Miller, 1988). Neurons, for example, produce action potentials to strong stimuli, and graded responses to weak ones, and so appear to have the ability for processing in either mode. Recently, interest in neural networks has led to a renewed interest in analog computing both for computer scientists (Mead, 1989) and psychologists.
