[The subject is shown pictures of a a log, a saw, an axe and a hammer and asked to select the one that does not go with the other three]

'They're all alike. I think all of them have to be here. See, if you're going to saw, you need a saw, and if you have to split something you need a hatchet. So they're all needed here.'

'Which of these things could you call by one word?'

'How's that? If you call all three of them a 'hammer', that won't be right either.'

'But one fellow picked three things—the hammer, saw, and hatchet—and said they were alike.'

'A saw, a hammer, and a hatchet all have to work together. But the log has to be here too.'

'Why do you think he picked these three things and not the log?'

'Probably he's got a lot of firewood, but if we'll be left without firewood, we won't be able to do anything.'

'True, but a hammer, a saw, and a hatchet are all tools.'

'Yes, but even if we have tools, we still need wood—otherwise, we can't build anything.'

(Luria, 1976)