Transitive inference in pigeons: measuring the associative values of Stimuli B and D

Several reinforcement-based models have been proposed to explain transitive-like behavior in nonverbal transitive inference tasks. These models assume that the initial training required for memorizing the premises produces an ordered series of associative values (A>B>C>D>E); these values can then be used to select the "transitively correct" stimulus in a novel pair (e.g., BD). Our study experimentally tested this assumption by using resistance-to-extinction and resistance-to-reinforcement techniques to obtain empirical measures of associative strength for Stimuli B and D. We first measured the associative strengths of these stimuli after completion of initial training with overlapping pairs of colored squares (A+B-, B+C-, C+D-, and D+E-) using resistance-to-extinction and resistance-to-reinforcement procedures. Next, we used massed presentations of Pair D+E- (termed bias reversal) that ought to increase the associative value of Stimulus D, and again measured the associative strengths of the stimuli. None of our experimental measures of associative strength correlated with pigeons' behavior in the BD test or with BD performance predicted by associative models either before or after bias reversal (Wynne, 1995; Siemann and Delius, 1998). These results question validity of reinforcement-based models for explaining animals' behavior in nonverbal TI tasks.