Irene Pepperberg's controversial research with captive African greys, including Alex, have shown that these parrots are capable of associating human words with their meanings, at least to some extent. Ambitious claims of language use have also been made for another African grey, called N'kisi; in the eyes of most experts in animal cognition, however, these claims are cast into doubt by the fact that this bird has also been claimed to exhibit powers of telepathy. There is little doubt that Greys and other parrots (especially macaws and cockatoos) are highly intelligent in comparison with other birds, but the oft-repeated claim that they have the cognitive abilities of a five-year-old human are not supported by any serious scientific evidence.

Pet owners often refer to their relationship with them as being "like having a five-year-old child." (See above) They are generally thought to be the best mimics of all parrots and can learn to imitate as many as 5,000 words. There have been perhaps apocryphal reports of some Greys learning the ultrasonic sounds of TV remote controls.

Anyone considering getting a Grey as a pet should note that they quickly become bored unless provided with stimulating toys and interaction with their owners. Their lifespans are 60+ years in captivity.

There are two subspecies:

Congo African grey parrot, Psittacus erithacus erithacus
Timneh African grey parrot, Psittacus erithacus timneh
Congo African greys (CAGs) are larger birds with light grey feathers, deep red tails and black beaks. The other subspecies, Timneh African greys (TAGs), are smaller in size, have a darker charcoal grey coloring, a darker maroon tail, and a lighter horn colored beak. A few authors recognize a third subspecies, Ghana African grey (Psittacus erithacus princeps), which is similar to CAG, but darker and slightly smaller.

The history of African greys kept as pets dates back over 4,000 years. Some Egyptian hieroglyphics clearly depict pet parrots. The ancient Greeks also valued parrots as pets, and this custom was later adopted by the Romans. Wealthy Roman families often kept parrots in ornate cages, and parrots were prized for their ability to talk. King Henry VIII of England also had an African grey parrot. Today, both wild-caught and captive-bred African greys are kept as pets.