You have to admit, though, no retriever is going to win a Nobel prize for anything more complicated than "Duh...".
/johnny
'Scuse me! We had to SPELL in front of my (late) female Golden. She was scary smart. She slipped a disc when she was 4 and couldn't do field work anymore. (She lived to 15 1/2) To entertain her, I invented the "bird" game. We kept a duck, or pheasant, wing in the freezer. I would hide it some place in the house, and tell her the "find the bird".
They only way I could stump her was to take the wing upstairs. That confused her. It was hilarious to watch her track my footsteps until she found the wing and brought it back to me. But when I took it upstairs, she'd stand at the bottom of the stairs sniffing the air and looking confused. She'd find it eventually.
She also wanted to cheat. Somebody would have to hold her and cover her eyes while I hid the wing because she'd try to peek around the corner to see where I was going. She was a great dog.