This chapter examines features of equipment design to understand their effects on operator performance. Aurally-presented information is likely to be the least confusing, but operators will tend to ignore aural information if presented repeatedly. Multi-function controls can be designed to reduce opportunities for mode errors by giving operators unambiguous information or feedback about the system's operating mode. Visually-presented information must be displayed properly for operators to efficiently obtain critical information. As with visually-presented information, modern equipment usually offers more flexibility in presenting aural information than does older equipment. Over the long term, as manufacturers slowly introduce new equipment and companies train operators to use the new equipment, standardizing controls and displays would reduce opportunities for error. Vehicles equipped with standard transmissions have two additional controls, a clutch and gearshift lever, for changing transmission gears as vehicle speed and engine rotation rates change.