Young children's causal inferences.

We report 2 experiments that show a striking development between the ages of 3 and 4 years in children's ability to make causal inferences about sequences of events. The task in the first experiment was to work out what had caused the change to an object that started out as odd (noncanonical) in 1 way and ended up as odd in 2 ways--starting, for example, as a broken cup and ending as a wet and broken cup. When asked to choose the instrument that had caused the change, 3-year-olds often selected the instrument that could have caused the initial state (a hammer, in our example) and not the instrument that would produce the change. 4-year-olds hardly ever made this mistake. In the second experiment, the 3-year-olds were able to make the correct choice when the change was from a canonical to a noncanonical state (cup-wet cup) but had much more difficulty when the change was from noncanonical to canonical (wet cup-dry cup). The difference was much smaller in the older group. The first of these tasks can be solved simply on the basis of knowledge that a particular instrument can cause a particular effect without reference to the initial state. The second task requires attention to the differences between initial and final state. We conclude that the ability to make genuine causal inferences develops between the ages of 3 and 4 years.