Although he has a brain the size of a walnut, Alex has redefined the term "bird-brain."
Alex is an African Grey parrot and has spent the past 22 years of his life learning a basic form of English under the guidance of scientist Irene Pepperberg.
And he isn't simply mimicking sounds. Alex means what he says. So far, he can recognize 50 different objects by name, distinguish quantities up to six, recognize seven colors and five shapes, and understand the concepts of "bigger," "smaller," "same," and "different."
When Dr. Pepperberg works with Alex, back in her lab at the University of Arizona in Tucson where she is a professor of biology, she teaches him by showing him objects made of different materials such as plastic, wood, or felt, and asking him questions such as "How many?" "What color bigger?" or "What color smaller?"
Pepperberg says Alex responds correctly about 80 percent of the time, much higher than would be possible by chance alone. "Sometimes he simply doesn't pay attention or guesses," she adds.
According to Pepperberg, the hardest test so far has been the comprehension test, when he had to look at seven objects on a tray and was asked "What object is shape X and color Y?" "What color is matter X and shape Y?" or "What shape is color X and matter Y?" while X and Y changed with every test.
Through the years, Pepperberg has devised complex and scientifically rigorous tests to make sure Alex isn't receiving cues from the researchers.
For example, students who had not participated in training Alex would conduct the tests. The answers have to be clear and understood. And sometimes Pepperberg takes note of Alex's performance with her back turned, blinding herself from the objects being shown.
When Pepperberg first began to work with Alex, she devised a method of training that took advantage of the parrot's natural learning behavior. They acquire their vocalizations from watching their peers and their parents.