Is their any fact based research that shows when customers expect a mouse scroll wheel to in fact scroll or zoom?
I believe context is appropriate vs. simply asking do you expect your mouse scroll wheel to scroll or zoom.
In a map the scroll wheel zooming in and out makes sense to me and feels natural. In a document that is laid out linear top to bottom scroll makes sense to in fact scroll.
But what about the grey areas? Geological applications, or industrial applications that show vertical plots of pressure data for example. Would the user expect to scroll through the data or are they taking the birds eye look, then zooming in for more detail then back out? In the case of geological plots I know the user is wanting to do both so it becomes difficult to clearly articulate why the scroll wheel action should be one or the other. My gut tells me this is again another linear relationship.
I was trying to define the context in simple terms such as maps that are spatial and documents that are linear. Not sure if that is a good rule to map the mouse wheel application action to.