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Monitoring and Cross-Checking Automation

The present study addresses effects of human redundancy on automation monitoring and cross-checking. Thirty-six participants performed a multi-task, consisting of three subtasks that mimic basic work demands of operators in a control room of a chemical plant. One of the tasks was to monitor and cross-check a highly reliable and safety-critical automated process. Participants were randomly assigned to two groups: (1) “Non-redundant”: participants worked on all tasks alone as the only responsible operator. (2) “Redundant”: participants were informed that a second crewmate would work in parallel on the automation monitoring task and that they both were responsible for ensuring safe operation of the automation. Results provide evidence for social loafing effects in automation cross-checking. Participants working redundantly with another crewmate were found to cross-check the automation significantly less than participants, who were working alone. Even if the combined team performance of the participants working in the redundant condition was considered, the number of cross-checks did not significantly differ from the performance in the non-redundant condition. This result suggests that human redundancy can induce social loafing effects which fully compensate a possible reliability gain intended to be achieved by this measure. It challenges the often stated assumption that “four eyes see more than two” and shows that human redundancy does not necessarily lead to enhanced safety in automation monitoring.