[5] Before Pepperberg's work with Alex, it was widely believed in the scientific community that a large primate brain was needed to handle complex problems related to language and understanding; birds were not considered to be intelligent, as their only common use of communication was mimicking and repeating sounds to interact with each other.

However, Alex's accomplishments supported the idea that birds may be able to reason on a basic level and use words creatively.

[7] She also reported that Alex seemed to show the intelligence of a five-year-old human in some respects,[4] and had not reached his full potential by the time he died.

[9] Animal psychologist Irene Pepperberg bought Alex at a pet store after finishing her PhD in theoretical chemistry, with the intent of studying his cognitive and communicative abilities.

Irene Pepperberg said the reward system is crucial, because it is the only way that students can make the direct connection between the object and the label that they have used.

[11][12] This technique helped Pepperberg succeed with Alex where other scientists had failed in facilitating two-way communication with parrots.

In later years, Alex sometimes assumed the role of one of Pepperberg's assistants by acting as the "model" and "rival" in helping to teach a fellow parrot in the lab, as well as correcting their mistakes.

[2] Alex passed increasingly difficult tests measuring whether humans have achieved Piaget's Substage 6 object permanence.

Alex showed surprise and anger when confronted with a nonexistent object or one different from what he had been led to believe was hidden during the tests.

[13] He named an apple a "banerry" (pronounced as rhyming with some pronunciations of "canary"), which a linguist friend of Pepperberg's thought to be a combination of "banana" and "cherry", two fruits he was more familiar with.

When asked questions in the context of research testing, he gave the correct answer approximately 80 percent of the time.

[19] Preliminary research also seems to indicate that Alex could carry over the concept of four blue balls of wool on a tray to four notes from a piano.

Some academics have expressed skepticism of Pepperberg's findings and suggested that Alex's communications is operant conditioning.