Learning sign language
In 1972, Patterson decided to talk to the zoo managers and ask to take care of Koko for at least a few years. During that time, she taught her sign language as the focus of her Ph.D. dissertation. Needless to say, her research was a complete success.
Not only did Koko use over 1,000 signs to communicate and create syntax-free sentences, but she also used them to sign about objects that weren’t in the room, recall memories, and even comment on language itself. In short, she did things that were only thought possible in humans!