Success and failure in expert reasoning

Relatively little is known about the causes of error in real-world problem-solving tasks. This paper attempts to address this lack of knowledge by considering errors as failures of reasoning and by focusing on human experts as a source of insight into the basis for reasoning errors. A theory of expertise for diagnostic tasks based on the hypothetico-deductive method of reasoning and two principles of expertise is described. The task of fraud detection in financial statement auditing is used as a context in which to develop and test the theory. Computer simulations of alternative models that embody violations of the two principles of expertise are described and tested on financial statements of actual companies. The performance of these models is also compared with a sample of 24 auditors who were given the financial statements of a subset of the companies. Results indicate that when neither of the two principles is violated, the performance of the resulting model is comparable with that of human auditors who are able to detect fraud. When either or both of the principles is violated, performance of the resulting models is comparable with that of auditors who fail to detect fraud in characteristic ways.