Alex was presented with two objects and asked to identify whether they were the same or different.

Sample: One African grey parrot.

Sampling Technique: Not specified.

Research Method: Case study.

Controls: Not specified.

Ethical Issues: The study involved working with an animal, and the researchers needed to ensure Alex's welfare and safety.

Results: The study found that Alex was able to correctly identify "same" and "different" in a variety of object categories.

Conclusion: The study suggests that parrots are capable of learning complex concepts and using language to communicate about them.

Strengths: The study provides a detailed account of Alex's learning process.

The study demonstrates the cognitive abilities of parrots.

Weaknesses: Small sample size limits generalizability.

The study's findings may be limited to Alex, the specific parrot involved in the study.