Computers have been used in their computational as well as noncomputational modes for the scientific study of the clinical decision making. As computational tools, computers serve as storage devices for hospital file data so that these data can be analyzed statistically for a large variety of epidemiological and diagnostic purposes. As noncomputational devices, computers are functioning as knowledgable medical teachers that interface with students who can query the system. In this mode, computers are sometimes used as consultants to clinicians who need information on technical topics. Noncomputational computers are also used to simulate the inferences of clinicians. Byproducts of these simulations are computer programs that become formal statements or theories of the decision processes under investigation.