TRANSITIVE INFERENCE FORMATION IN PIGEONS

Pigeons were trained with 4 pairs of visual stimuli in a 5-term series-A+ B-, B+ C-, C+ D-, and D+ E-(in which plus [+] denotes reward and minus [-] denotes nonreward)-before the unreinforced test pair B D was presented. All pigeons chose Item B, demonstrating inferential choice. A novel theory (value transfer theory), based on reinforcement mechanisms, is proposed. In Experiment 2, the series was extended to 7 terms. Performance on test pairs was transitive, and performance on training pairs accorded with the theory. The 7-term series was closed in Experiment 3 by training the first and last items together. In accordance with the theory, the Ss could not solve the circular series. The authors suggest that primates, including humans, also solve these problems using the value transfer mechanism, without resorting to the symbolic processes usually assumed.