Covariance, feedback, and discounting in ratio schedules

Action-outcome relations in the everyday world are often looser than the relations programmed in the laboratory. Reinforcement theory addressed this looseness by theorizing about "delay of reinforcement." Response-reinforcer interval affects response rate and choice, but need not be thought of as delay. Experiments on temporal discounting are often said to reveal effects of delay also, but the intervals chosen differ from delays, because an outcome after a week, month, or year occurs after life has continued and many events have intervened. They are better called lag intervals. The present experiment studied the effects of varying lag interval on pigeons' responding on ratio-like schedules of food. In a continuous procedure, a lag interval separated pecking that earned food from delivery of the food earned. In one series of conditions, the relation was fixed equivalent to variable-ratio (VR) 40 while the lag interval varied. In a second series, the equivalent VR varied while the lag interval was fixed. The results accorded with matching theory, but with a factor for temporal discounting or loose feedback. The results suggest that both temporal discounting and probability discounting may be characterized within matching theory, but that temporal discounting requires a separate treatment from probability discounting.