Principles of Perception, Design, and Comics
Filling in the gaps. Bobby McFerrin didn't ask everyone to guess a sound - he started a pattern with one sound, then another, and another. The relationship between those sounds is design (the Pentatonic Scale), the audience participating to fill in the gaps demonstrates the Closure principle of perception.
I came across this video while preparing for a special series of the Lean Into Art Cast centered on the topic of Design. Andy Rutlege's blog is a fantastic resource on Design. A great place to start exploring his writing is his 5 part Gestalt Principles of Perception series.