Hey people who have several pets, with obvious differences in intelligence levels: How did you figure out that one of them is smarter than the other? What do they do?
There are a lot of things that lead me to think my elder cat is unusually intelligent compared to other felis domesticus I have known (understands pointing, can open every door and cabinet in the house except the ones with round knobs or that I added child locks to, understands enough English to know from a phone conversation that a stranger is coming to the house) but in terms of specifically comparing one to the other, there was The Case Of The Mousey Puzzle Box.
When we got our younger cat Skadi, her favorite toy was (still is, but she's calmed down with age) the rattley mouse. She would bring the mouse to be thrown for fetch so many times that not even two human adults in the house could keep up with her. So my partner started making puzzle boxes to put the rattley mouse in that would occupy her for longer.
So, we have a setup: mouse is in the puzzle box, puzzle box is on the floor, younger cat is trying to resolve the puzzle box, elder cat is sitting on the cat tree observing all this. Skadi spends about fifteen minutes trying and failing to get the mouse out of the box. She sticks her paw into the holes. She sticks her nose into the holes. She pushes the box to and fro on the carpet. She meows beseechingly for a human to come solve the problem. Sticks her paws into the holes again.
Finally, she gives up on the puzzle box and wanders over to see if there's any food to be had. As soon as she walks away the elder cat gets up from the cat tree, big stretch, jumps down, walks over to the puzzle box, hooks a paw under the edge and flips the whole thing over, spilling the mouse onto the floor.
Gives the younger cat a look of utter disgust as if to say "That's all you had to do!" and then walks away, utterly uninterested in actually playing with the toy.
Older cat just subjected to fifteen minutes worth of those horrible mobile game ads where the player is failing really badly to make you want to play.
