The side-effect that destroyed touch-screens as a mainstream input technology despite a promising start in theearly 1980s. It seems the designers of all thoseef="module.php?name=Lexikon&file=search&eid=1&query=spiffy">spiffy touch-menu systems failed to notice that humans aren' t designed to hold their arms in front of their faces making small motions. After more than a very few selections, the arm begins to feel sore, cramped, and oversized - the operator looks like a gorilla while using the touch screen and feels like one afterward. This is now considered a classic cautionary tale to human-factors designers "Remember the gorilla arm!" is shorthand for "How is this going to fly in *real* use?".
