PIGEONS OBSERVING BEHAVIOR AND RESPONSE-INDEPENDENT FOOD PRESENTATIONS

Food-deprived pigeons were exposed to a one-key observing response pro cedure. Discrete trials ended either with or without response-independ ent food presentation (p = 0.5); trials were prolonged until no respon ding had occurred for at least 3 s. Key pecks (observing responses) co uld produce discriminative stimuli correlated with the trial outcome, either S+ (food) or S- (no food). Under some conditions, pecks produce d both stimuli on a 15-s variable-interval (VI) schedule. Under other conditions, a minimum 6-s interresponse time was required after comple tion of the VI (tand VI DRL) to produce one of the stimuli. For all bi rds, the tand VI DRL contingency resulted in a much greater and more p rolonged decrease in stimulus production when it was applied to S-tria ls than when it was applied to S+ trials. The results are consistent w ith conditioned reinforcement theories such as the delay-reduction the ory. (C) 1998 Academic Press.