Mental Set and Complexity Effects in the Diagnosis of Simultaneous Faults in a Simple Binary Adder

Abstract

This paper focuses on the challenge to human diagnostic reasoning posed by multiple faults. Two sources of difficulty were tested; mental set and multiple fault complexity. Mental set was manipulated by training subjects on single or multiple faults and then transferring them to multiple fault diagnosis. Half the subjects were transferred to a multiple fault with simple easily separable symptoms and the other half to one with more complex highly interactive symptoms. Results suggest that mental set and multiple fault complexity affect the correctness, latency and subjective workload of transfer multiple fault diagnosis, but not the number or range of tests made before the final diagnosis. Inability to diagnose the transfer multiple fault was wholly due to (1) failure to explore the symptom space so as to see the sufficient and necessary evidence to diagnose the multiple fault (2) failure to consider the possibility of multiple faults, or (3) both.