Illusions developed by magicians are a rich and largely untapped source of insight into perception and cognition. Curved motion, as employed by the magician in a classic sleight of hand trick, generates stronger misdirection than rectilinear motion.

The French Drop is a classic sleight of hand magic trick, as seen on the video on the right.. This simulated maneuver results in the perception that the coin has magically vanished from the right hand.

Sourced from https://www.youtube.com/watch?v=EZ0C2wh5IyE at 7.47 pm2/10/20

The French Drop can be performed using either curved or straight hand motion. Although the illusion is effective either way, research concludes that curved motion, when used in the French Drop or similar sleight of hand tricks, is a more powerful source of misdirection than straight motion.