Which parrot species was the focus of Irene Pepperberg's research?

Irene Pepperberg’s landmark parrot research focused on the African grey parrot.

Pepperberg became known for studying whether parrots could use human words meaningfully rather than merely imitate sounds. Her best-known research participant was Alex, an African grey parrot whose performances involved naming, requesting, answering questions, and distinguishing properties of objects.

African grey parrots were especially useful for this work because they are highly social, vocal learners with strong capacities for auditory imitation. Pepperberg’s training approach, often called the model-rival technique, used interactions between people to encourage the bird to attend to labels and their consequences.

The research did not show that parrots speak human language exactly as people do. Instead, it demonstrated sophisticated learning of vocal labels and concepts, including colors, shapes, materials, quantities, and comparisons. Alex is the famous individual most associated with the work, but the species-level answer is African grey parrot.