Abstract: The Power PC theory was tested by using the concentrative presentation of graph representation of information and the paradigm of comparing causal power. The participants were 233 college students. The results showed that comparative judgments of causal power of single causal relationships had the following characteristics: (a) Most judgments were in accord with the Power PC theory in the conditions of preventive causes, but conversely most judgments were not in accord with the theory in the conditions of generative causes, (b) in the condition of generative causes with simultaneous changes of the covariation coefficient and the base rate of the effect, most participants used the DP rule of probabilistic contrast model, which was not in accord with the Power PC theory, and (c) in the condition of generative causes with the change of the base rate of the effect and the constant covariation coefficient, most participants used the RP rule, which couldn’t be explained by all known theories of causal reasoning.

Key words: Power PC theory, Probabilistic Contrast Model, comparative judgments of causal power, concentrative presentation, graph representation of information, unsymmetry