Mechanisms Underlying the Effects of Unsignaled Delayed Reinforcement on Key Pecking of Pigeons Under Variable‐interval Schedules

Abstract

Three experiments were conducted to test an interpretation of the response-rate-reducing effects of unsignaled nonresetting delays to reinforcement in pigeons. According to this interpretation, rates of key pecking decrease under these conditions because key pecks alternate with hopper-observing behavior. In Experiment 1, 4 pigeons pecked a food key that raised the hopper provided that pecks on a different variable-interval-schedule key met the requirements of a variable-interval 60-s schedule. The stimuli associated with the availability of the hopper (i.e., houselight and keylight off, food key illuminated, feedback following food-key pecks) were gradually removed across phases while the dependent relation between hopper availability and variable-interval-schedule key pecks was maintained. Rates of pecking the variable-interval-schedule key decreased to low levels and rates of food-key pecks increased when variable-interval-schedule key pecks did not produce hopper-correlated stimuli. In Experiment 2, pigeons initially pecked a single key under a variable-interval 60-s schedule. Then the dependent relation between hopper presentation and key pecks was eliminated by arranging a variable-time 60-s schedule. When rates of pecking had decreased to low levels, conditions were changed so that pecks during the final 5 s of each interval changed the keylight color from green to amber. When pecking produced these hopper-correlated stimuli, pecking occurred at high rates, despite the absence of a peck-food dependency. When peck-produced changes in keylight color were uncorrelated with food, rates of pecking fell to low levels. In Experiment 3, details (obtained delays, interresponse-time distributions, eating times) of the transition from high to low response rates produced by the introduction of a 3-s unsignaled delay were tracked from session to session in 3 pigeons that had been initially trained to peck under a conventional variable-interval 60-s schedule. Decreases in response rates soon after the transition to delayed reinforcement were accompanied by decreases in eating times and alterations in interresponse-time distributions. As response rates decreased and became stable, eating times increased and their variability decreased. These findings support an interpretation of the effects of delayed reinforcement that emphasizes the importance of hopper-observing behavior.

Assessing the role of alternative response rates and reinforcer rates in resistance to extinction of target responding when combining stimuli

“…Experiment 1 showed that reinforcers dependent upon a spatially separated but topographically and functionally identical alternative response reduced target responding in extinction more than an equal rate of response‐independent food presentations. Thus, the alternative response of keypecking producing food reinforcers interfered with target responding more than the responses occurring in the presence of response‐independent reinforcers (e.g., hopper attending; Schaal, Shahan, Kovera, & Reilly, ; Staddon & Simmelhag, ). Unfortunately, the present study did not assess the extinction of target responding on its own to compare target responding with and without the alternative stimulus and to assess the extent to which those other responses might have interfered with target responding (cf.…”

A quantitative analysis of the effects of qualitatively different reinforcers on fixed ratio responding in inbred strains of mice

“…To the extent that mice consumed sucrose pellets moments after the lever press that produced them, these conditions are analogous to those arranged in studies of unsignaled, non-resetting delayed reinforcement (see Lattal, 2010). Therefore, the lower estimates of response time under sucrose pellets likely resulted from the effects of intermittent delayed reinforcement of lever pressing (or releasing), and greater coupling of non-target responses (Shahan & Lattal, 2005; Schaal, Shahan, Kovera, & Reilly, 1998). …”

The modulation of operant variation by the probability, magnitude, and delay of reinforcement

“…There is some empirical evidence to suggest that a temporal delay to reinforcer delivery in an operant task may increase the variability of pigeons’ terminal behavior. In a key-pecking task in pigeons, Schaal, Shahan, Kovera, and Reilly (1998, Exp. 3) observed that variability in the latency to consume grain reward was greater when there was a 3-s interval between an operant response (i.e., the key peck) and the delivery of grain than when grain was delivered immediately after the response.…”