Pigeons' Observing Behavior and Response-Independent Food Presentations

Abstract

Food-deprived pigeons were exposed to a one-key observing response procedure. Discrete trials ended either with or without response-independent food presentation (p= 0.5); trials were prolonged until no responding had occurred for at least 3 s. Key pecks (observing responses) could produce discriminative stimuli correlated with the trial outcome, either S+ (food) or S− (no food). Under some conditions, pecks produced both stimuli on a 15-s variable-interval (VI) schedule. Under other conditions, a minimum 6-s interresponse time was required after completion of the VI (tand VI DRL) to produce one of the stimuli. For all birds, the tand VI DRL contingency resulted in a much greater and more prolonged decrease in stimulus production when it was applied to S− trials than when it was applied to S+ trials. The results are consistent with conditioned reinforcement theories such as the delay-reduction theory.