So what’s wrong with Mac OS X’s mouse acceleration curve? Simply put, it’s the wrong shape. For mouse motion to feel natural (at least for most people), the curve has to start by moving upward fairly moderately, then gradually flattening out as the value of X increases. Mac OS X’s, curve, however, starts off by being too steep, staying too steep for too long, and then flattening out too abruptly. In practical terms this means that, frequently, as a user tries to use the mouse to move the pointer from point A to point B, the pointer motion feels sluggish. The user then tries to compensate for the sluggishness by moving the mouse faster, and the pointer suddenly goes flying across the screen and overshoots point B. A comfortable and useful curve is actually shaped like a curve. Mac OS X’s curve, however, is shaped more like a cliff.