Study
Acquisition of the same/different concept by an African Grey parrot (Psittacus erithacus): learning with respect to categories of color, shape, and material
Pepperberg, Irene M.
Animal Learning & Behavior, 1987
An African grey parrot trained by a social modelling procedure was shown pairs of objects varying in colour, shape and material and asked which attribute was the same or different, including with novel objects and attribute combinations he had not been trained on.
- Studied in
- Psittacus erithacus
- Sample size
- 1 African grey parrot (Alex), tested over many trials
The parrot answered correctly well above chance with novel objects, and could report which category the objects differed in rather than only that they differed.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
The parrot had acquired the abstract concepts of same and different and could apply them across categories to unfamiliar stimuli.
How NatureHQ reads it
The best evidence anywhere that a parrot’s speech can be more than imitation — and it is one bird, over thirty years, trained by a method most parrots never encounter. Two things get run together in popular accounts and should not be. Alex was answering questions about objects in front of him, which is a real and demanding cognitive achievement, and it is not evidence of syntax, of talking about absent things, or of anything a pet parrot does. The single-subject design is a genuine limitation and was flagged as one throughout by the researcher herself.
- A single individual, extensively trained by a specific social method — no basis for generalising to parrots as a group.
- Single-subject designs cannot rule out cueing as thoroughly as group designs, though this work used blind testing to address it.
- Concept use in the presence of the objects establishes nothing about reference to what is absent.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Springer journalsPublished in a Springer journal.
Checked against Crossref and OpenAlex on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-02.