But by using novel methods of teaching, Dr. Pepperberg prompted Alex to learn about 150 words, which he could put into categories, and to count small numbers, as well as colors and shapes. “The work revolutionized the way we think of bird brains,” said Diana Reiss, a psychologist at Hunter College who works with dolphins and elephants. “That used to be a pejorative, but now we look at those brains — at least Alex’s — with some awe.”

Other scientists, while praising the research, cautioned against characterizing Alex’s abilities as human. The parrot learned to communicate in basic expressions — but it did not show the sort of logic and ability to generalize that children acquire at an early age, they said. “There’s no evidence of recursive logic, and without that you can’t work with digital numbers or more complex human grammar,” said David Premack, a professor emeritus of psychology at the University of Pennsylvania.

Dr. Pepperberg used an innovative approach to teach Alex. African Greys are social birds, and pick up some group dynamics very quickly. In experiments, Dr. Pepperberg would employ one trainer to, in effect, compete with Alex for a small reward, like a grape. Alex learned to ask for the grape by observing what the trainer was doing to get it; the researchers then worked with the bird to help shape the pronunciation of the words.

Alex showed surprising facility. For example, when shown a blue paper triangle, he could tell an experimenter what color the paper was, what shape it was, and — after touching it — what it was made of. He demonstrated off some of his skills on nature shows, including programs on the BBC and PBS. He famously shared scenes with the actor Alan Alda on the PBS series, “Look Who’s Talking.”

Like parrots can, he also picked up one-liners from hanging around the lab, like “calm down,” and “good morning.” He could express frustration, or apparent boredom, and his cognitive and language skills appeared to be about as competent as those in trained primates. His accomplishments have also inspired further work with African Grey parrots; two others, named Griffin and Arthur, are a part of Dr. Pepperberg’s continuing research program.