Concepts and transformational knowledge.

The effect of exposure to principled change in concept formation was investigated in four experiments. In Experiment 1, participants were trained on either patterns that transformed systematically or control patterns that were distorted randomly. Training on transformational patterns produced concepts that were more resistant to false intrusions and decay. Experiment 2 separated the relative influences of transformational knowledge and pairwise similarity. Participants were able to identify the next pattern in a transformational sequence even though the foils were closer to the training patterns. Experiment 3 investigated whether participants use transformational information in a speeded categorization task. Participants were faster at classifying patterns that continued a transformational path than patterns that fell off the path, only if they had trained on the transformational patterns in a systematic order. Experiment 4 used multidimensional scaling to explore the psychological structure of transformational knowledge following training. Analyses revealed clear evidence of a transformational path with systematic training. Implications for theories of similarity and categorization are discussed.