Steering wheel or driving wheel: which way is up?

Many functions other than scrolling may be mapped onto the wheel of the computer mouse. These include zooming, in browsers or viewers, and controlling the volume, in audio applications. Competing applications designed for accomplishing the same task, listening to audio files or reading webpages, for example, require that the scrollwheel be turned in opposite directions to achieve the same effect. This paper argues that the two opposite grammatical rules applied in designing the application interfaces actually reflect different underlying metaphorical concepts. The rules of interface grammar may be in flux or competing dialects may assign different semantic values to the same mouse-wheel gesture