Larry Tesler on the History of Scrolling Direction on the Mac

Larry Tesler:

The original Lisa and Mac vertical scroll arrows were at the top and bottom of the vertical scroll bar, and the up-pointing arrow moved the content down. I ran a user study in the early days of Lisa development that informed that design.

Most (but not all) study participants expected to position the mouse near the top of the window to bring the content hidden above the top of the window into view. One reason was that they were looking at the top of the window at the time. Another reason was that they were more likely, as their next action, to select content in the upper half of the window than in the lower half. Consequently, we made the upper member of the arrow pair move the content down. With apologies to computer architects, I’ll call the majority whose expectations were met by this decision the “top-endians”.

★ Monday, 25 July 2011