“Functional Vocalizations by an African Grey Parrot (Psittacus erithacus)”

This is a seminal article in Pepperberg’s research on Grey parrots. An African grey parrot, after 26 months of speech training, has acquired a verbal vocabulary consisting of three color adjectives, two phrases for describing shape, 9 nouns, and functional use of the word “no.” The parrot is capable of correctly combining these vocalizations so as to identify proficiently, request, and/or refuse more than 30 objects by means of verbal labels.