Associative factors underlying the pigeon's key pecking in auto-shaping procedures.
Key pecking in pigeons can be engendered by associating response-independent food presentations with illumination of a key. Specific pairings of key and food are not necessary for this phenomenon. Differential positive association between key and food (defined in terms of relative densities of reinforcement), however, is necessary and sufficient to produce and maintain key pecking. Thus, the occurrence of key pecking in auto-shaping can be considered to depend on associative processes similar to classical conditioning. Consequently, auto-shaped pecking can be virtually eliminated by the addition of food presentations in the intertrial interval, thus removing the association between key and food. Initial exposure to random reinforcement, or reinforcement only in the absence of the key, results in lower rates of pecking in subsequent auto-shaping procedures.