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Two experiments a sessed effects of activation of prior knowledge through small-group discussion. Subjects were given a description ofnatural phenomena and were asked to elaborate on possible explanations for them. In Experiment 1,small groups of subjects were presented with a problem describing the behavior of a blood cell in pure water and in a salt solution. No additional text was studied. The experimental subjects produced more than twice as many propositions about osmosis (i.e. the biological process explaining the blood cells behavior) as a control group produced. Experiment 2 investigated ffects of problem analysis on subsequent text processing for subjects with imprecise prior knowledge (novices) and subjects with precise knowledge (experts). Recall of the text showed considerable facilitative effects of problem analysis. Results are explained in terms of faster accessibility of prior knowledge and better integration of new information i to explanatory models that may exist before, or are actively constructed during, problem analysis. Attempts to understand the physical world involve the use of cognitive structures that represent mechanisms or princi-ples underlying the phenomena observed. These cognitions
Schmidt et al. (Fri,) studied this question.