Playing charades with orangutans. A Foxnews story relates the research of Matt Cartmill on primate communications. The story notes:

"The orangutans made a clear distinction between total misunderstanding, when they tended to give up on the signals they'd used already and use new, but equivalent, ones to get the idea across, and partial misunderstanding, when they tended to repeat the signals that had already partially worked, keeping at it with vigor," Cartmill said. "The response showed that the orangutan had intended a particular result, anticipated getting it and kept trying until it got the result."

[Richard]Byrne noted that "looking at the tapes of the animal's responses, you can easily work out whether the orangutan thinks it has been fully, partially or not understood."

I guess we all need to communicate.