I have been lucky enough to go to a "bird nerd" lecture with Dr. Irene Pepperberg, who has done amazing studies with African Grey Parrots.
She has done a 30- year plus study with the parrots. She tried to teach them to distinguish between different sorts of matter, different colors and shapes. Alex could say the answer to her questions most of the time...it was pretty cool.
Check it out if you are interested. Click away: http://www.alexfoundation.org/
If you are interested let me know and I'll post video.
It is pretty amazing but I don't want to bore the non-animal people.