To provide various functions such as an in-vehicle information system, in-vehicle displays are continuously becoming larger. The head-up display, which shows information on windshields, has entered the spotlight. While in the past, invehicle head-up displays showed simple information including driving speed and distance between cars, they recently started displaying complex information including advanced driver assistance information. Therefore, tracking tasks are required to search for

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... ion on the head-up display, similar to the menu navigation of in-vehicle information systems. Tracking tasks are controlled by multiple controllers of the driving information system. This study aimed to identify the effects of three levels of visual enhancements, including no visual enhancement, shaded reference bar, and translucent reference bar, on the information search.