Assessing power PC.

In a recent theoretical paper, Cheng (1997) presented a new causal model, power PC. She argued that power PC was able to account for data in the literature that raised problems for associative models--notably, the Rescorla-Wagner model (Rescorla & Wagner, 1972). The purpose of the present paper is threefold: (1) to show that, overall, the data in the literature, which Cheng relied on to make her case, do not in fact provide support for power PC, (2) to show that, overall, the experiments reported in the literature since the publication of Cheng, designed specifically to evaluate the predictions of power PC, also do not provide support for power PC, and (3) to suggest that Cheng's assessment of associative models was too narrowly defined.