The Absence of Degree of Automation Trade-Offs in Complex Work Settings.

<bold>Objective: </bold>The objective of this study was to test the predictions of the routine-failure trade-off (or lumberjack) model in a full-scope simulator study with expert operators performing realistic control tasks.<bold>Background: </bold>A meta-study of degree of automation (DOA) studies concluded that DOA predicts task performance under both routine and automation failure conditions, workload, and situation awareness. Empirical support for this conclusion appears to be weak for complex work situations.<bold>Method: </bold>A full-scope nuclear power plant simulator experiment was conducted in which licensed operating crews completed realistic procedure execution tasks. Dependent measures selected from the lumberjack model were collected and analyzed for systematic effects.<bold>Results: </bold>Situation awareness increased with increasing DOA, which contradicts the lumberjack model. Anticipated workload and failure task performance effects were not observed.<bold>Conclusion: </bold>The experimental results add further evidence challenging the applicability of the lumberjack model to complex work situations.<bold>Application: </bold>Practitioners should use caution when extending the predictions of the lumberjack model based on data from simple work situations to complex work situations. Researchers should invest more resources in testing the predictive power of the lumberjack model in complex work situations. [ABSTRACT FROM AUTHOR]