Yeah, I think the design of the experiment is good to catch this potential weakness. If it was the knowledgeable experimenter instructing the children, that co

Yeah, I think the design of the experiment is good to catch this potential weakness. If it was the knowledgeable experimenter instructing the children, that could really confuse things. I think it's still potentially a source of confusion, but less of one. If you imagine that instead of sorting 4 figurines they had to sort 400, then it would be easy to see that the kids aren't going to test all of them. Too boring. They may not even go to the trouble of testing a sample of the figurines. The would need some incentive to drive them to do a bit more work than the bare minimum. If I ask my son to clean his room, and I return to discover he's done a poor job, I will not think that he doesn't understand how to clean his room. Similarly, if these kids are asked to sort figurines and they just go by what they're told (or what they observed) without testing, that doesn't necessarily mean they don't understand that testing might be useful.