Technological and strategic developments have changed the role of human operators in the manufacturing environment. The highly specialized work force of the low-tech manufacturing system has evolved into the multi-functional work force of the high-tech manufacturing system. Among the multiple tasks that an operator is expected to conduct in advanced manufacturing systems (AMS) are job scheduling, inventory planning, machine set-up, problem solving, and quality inspection.The quality inspection task in AMS consists of a search component, frequently conducted by a machine, and a decision making component conducted by the operator.This quality inspection system is often referred to as a hybrid inspection system (HIS). It has been demonstrated that in general the performance of HIS is better than that of pure human or pure automated inspection systems. This research investigated the effects of different types of defects (presented at the same time in the inspected parts), multitasking (concurrently conducting independent tasks), and their interaction on the operator's performance in the quality inspection task (with a memorized quality criteria) in an AMS.The results indicate that the performance of the operator in the quality inspection task while multitasking in an AMS will be determined not only by the variety of defects that can be present in the inspected parts, but also by the mental processing resources required to meet the demand imposed by the multiple independent tasks and the memorized quality criteria. The best performance will be obtained when the additional tasks' load minimizes the monotony of the quality inspection task without interfering with the processing resources needed for the memorized quality criteria.iii Dedicated to the memory of my father, José Pesante iv