INTRODUCTION: The recent developments of technology in almost all areas of industrial processing, workplace, smart homes, mobility, media, and communication change humans’ everyday life environment and behavioral responses in numerous ways. Our main objective in this study was to determine whether subjects’ operator performance in a complex sensorimotor task is associated with their gaze behavior.METHODS: In two experiments subjects operated a complex control task. To this end they watched multiple displays, made strategic decisions, and used multiple actuators to maximize their virtual earnings from operating a virtual power plant. In Experiment 1 we compared gaze behavior during the tasks with respect to operator performance in two different age groups (young vs. old), and in Experiment 2 in two different gravity conditions (normal vs. microgravity).RESULTS: We found gaze pattern changed in older subjects as well as in microgravity. Older adults and subjects in microgravity looked longer at areas that are less relevant for task success. Most importantly, these changes in gaze pattern accounted for the effects of age and microgravity and on total earnings in the instrument-control task.DISCUSSION: In conclusion, age- and gravity-related changes of gaze behavior show a similar pattern. Gaze behavior seems to play an important role in complex control tasks and might predict alterations of operational performance.Kalicinski M, Steinberg F, Dalecki M, Bock O. Gaze behavior while operating a complex instrument control task. Aerosp Med Hum Perform. 2016; 87(7):646–651.