Acquired distinctiveness is controlled by stimulus relevance not correlation with reward

In 2 experiments, the relationship between the role of a stimulus in signaling trial outcome and the attention paid to it was investigated. In Exp 1, an intradimensional–extradimensional shift effect was shown in pigeons using autoshaping. In Exp 2, pigeons were trained with a biconditional discrimination, using stimulus compounds varying on 3 dimensions (color, orientation, and position), 2 of which were relevant to the solution of the discrimination, and 1 of which was irrelevant. Acquisition of a subsequent biconditional discrimination was more rapid if the same stimulus dimensions were relevant to the solution of both discriminations than if a previously irrelevant discrimination became relevant. These results indicate that the amount of attention paid to a stimulus is determined by its relevance to the solution of a discrimination, and not by its correlation with reward