Comparing patterning and biconditional discriminations in humans.

In two experiments, human participants performed a causal judgment task that simultaneously comprised two reciprocal patterning discriminations and a biconditional discrimination. They learned both patterning discriminations more quickly than the biconditional discrimination. Postdiscrimination tests were used to identify participants who had, or had not, learned to apply the patterning rules, as well as participants who continued to expect summation when presented with two cues that predicted the same outcome. All groups were faster to learn the patterning than the biconditional discriminations. These results are inconsistent with models of stimulus representation that invoke configural representations (e.g., Pearce, 1987, 1994; Rescorla & Wagner, 1972) because these models solve biconditional discriminations more readily than patterning discriminations.