| Abstract: | Pigeon subjects were used in five experiments investigating second-order conditioning with visual second-order and diffuse auditory first-order stimuli. Experiment 1 used a discriminative conditioning procedure to demonstrate reliable and substantial second-order conditioning with these stimuli. In Experiments 2 and 3, extinction of the auditory first-order stimulus after second-order conditioning had little effect upon responding to the second-order stimulus, when compared to a stimulus whose reinforcer was maintained. Experiment 4 compared directly the susceptibility of second-order responding to extinction of the first-order reinforcing stimulus as a function of the modality of that reinforcer. When a visual second-order stimulus was paired with a visual reinforcer, and the response to the latter was extinguished, then second-order responding was greatly reduced relative to control levels. In contrast, when that reinforcer was an auditory stimulus, second-order responding was not affected by the current value of the first-order stimulus after conditioning. Finally, in Experiment 5 the auditory stimulus was established as a reinforcer through discriminative-operant training. Following second-order conditioning, extinction of responding to this stimulus again had little impact upon responding to the second-order stimulus with which it had been paired. These results are discussed in terms of previous work on second-order conditioning with rat and pigeon subjects. |
