My dog recognizes the sounds a Waymo car makes

Most of us know the general (albeit simplified) story: Russian physiologist Ivan Pavlov used a stimulus—like a metronome—around the dogs he was studying, and soon, the hounds would start to salivate.

They had learned that the sound meant food was coming. The phenomenon, now known as classical conditioning, became one of modern psychology’s foundational discoveries. It’s an unconscious process where a neutral stimulus becomes associated with a naturally occurring stimulus, eventually leading to a connection between the two.