I also wondered about the difference between doing this with young children and adult chimps.

I think it’s fairly obvious that if you gave the clear box test to a teenager or adult and said “get the treat out” they’d look at you funny and then many or most would just reach in and grab it. I think even in the black box, they’d probably look at it real hard and maybe try going straight for the treat after investigating the box a bit.

By contrast very young humans operate in “game mode” almost all the time, and are basically “playing along” with whatever game you put them in. It’s a lot of fun, and often silly.

So my question is, what about juvenile chimps? Do they also operate in game mode, or would they follow the adult chimp behavior of going straight for the reward?