Carl Sagan's Encounter With a Dolphin's Theory of Mind

I was swimming in a large indoor pool with Peter. When I threw the pool's rubber ball to Peter (as was natural for me to have done), he dove under the ball as it hit the water and batted it with his snout accurately into my hands. After a few throws and precision returns, Peter's returns became increasingly inaccurate – forcing me to swim first to one side of the pool and then to the other in order to retrieve the ball. Eventually, it became clear that Peter chose not to place the ball within ten feet of me. He had changed the rules of the game.

Peter was performing a psychological experiment on me – to learn to what extreme lengths I would go to continue this pointless game of catch. It was the same kind of psychological testing that Elvar had conducted in our first meeting. Such testing is one clue to the bond that draws dolphins to humans: We are one of the few species that have pretensions of psychological knowledge; therefore, we are one of the few that would permit, however inadvertently, dolphins to perform psychological experiments on us.

Carl Sagan, Carl Sagan's cosmic connection (2000-10-23)

• animal intelligence
• dolphin
• theory of mind