Comment by thomastjeffery

He's my theory: We use backstory to resolve ambiguity.

The ambiguity: "What's this a picture of?"

A possible answer: "a duck"

A backstory that gets us there: "The area colored white is background, and the area colored black is the foreground, and a black area with that shape of edge matches the silhouette of a duck."

Another ambiguity: "Why is the white not foreground?"

A backstory that gets us there: "Paper is white, ink is black, and when I want to draw, I use the ink to draw the duck on the paper."

So can we conclude that any person who answers "duck" got there through this particular backstory? Of course not! There are plenty of alternative paths to this conclusion.

The intention behind any ambiguous expression is lost forever. The choice of backstory will always be arbitrary.