Blocking in Humans: Logical Reasoning Versus Contingency Learning

This study compared the occurrence of the blocking effect when participants had unlimited and limited time to respond to a causal learning task. In contrast to the dominant views in human causal learning, the underlying assumption is that blocking can be sufficiently explained by the same principles that describe conditioning outcomes in animals, but only when logical reasoning about the experimental task is impeded. Experiment 1 compares responses to blocking tests by participants in timed and untimed groups. As expected, most cases of blocking were observed for participants in the timed group. Experiment 2 explores an alternative procedure in which all information about stimulus-outcome associations was simultaneously present. Based on this information, participants sorted target and control stimuli according to their predicted of outcomes. Very limited evidence of blocking was observed with this procedure. Findings are discussed in terms of the interference of rule generation processes with direct contingency control.