Zweifachers

The zweifacher is a Bavarian (German) dance that alternates waltz steps (in 3) with pivots (in 2). It's lots of fun because it's intensely dizzy. Now I know why (sort of). The semicircular canals in your ears which sense angular rotation are stimulated by changes in acceleration. Because a waltz or a merry-go-round or spinning in a chair has constant angular velocity, eventually the vestibular system will accommodate to the motion, making it less dizzy. But in the case of zweifachers, alternating waltzes and pivots causes an angular acceleration (or deceleration), leading to increased dizziness.