[Jerome] Bruner described three distinct stages in the learning process, each of which has a different state of mind: "Enactive, iconic, and symbolic." This was illustrated by an experiment with two water glasses, one short and fat, and the other tall and thin. When children are shown the contents of the short glass being poured into the tall one, they will say that there is more water in the tall one, even though they saw the pouring. If you then hide both glasses, the children change their minds, reasoning that the water had nowhere else to go. This could be done several times; each time the children would repeat the assertion that there was more water in the tall thin glass whenever they could see it but deny it when it was not visible. The experiment illustrates the different mental states that underlie our learning process. [The research cited is from Jerome Bruner, Toward A Theory of Instruction, 1966]