Punishment as a discriminative stimulus and conditioned reinforcer with humans

Mental hospital patients were reinforced for responding in a two-response operant situation. When a noise was used to punish one of the responses, all subjects shifted to the unpunished one. When the noise was then paired with positive reinforcement, the subjects responded to produce the noise. Also, a novel response was reinforced by noise in the absence of other reinforcers. This study with humans extends the findings of previous studies with animals in revealing how a punishing stimulus can acquire discriminative or conditioned reinforcing properties.     

The effect of multiple SΔ periods on responding on a fixed-interval schedule: V. Effect of periods of complete darkness and of occasional omissions of food presentations

In pigeons under fixed-interval schedules of reinforcement, responding during most of the interval can be suppressed by stimulus conditions never present when a response is promptly followed by reinforcing stimuli. When the external stimuli obtaining immediately before reinforcement are presented during brief probe periods in the course of the interval, the rate of responding in the probe depends on the temporal position of the probe during the interval; the rate of responding is lower during a probe early in the interval than during one late in the interval. The present experiments show that the temporal dependency still holds (1) in birds with no experience under unmodified fixed-interval schedules, (2) when the time between probes is spent in complete darkness, and (3) when food presentations are omitted at the end of 50% of intervals. The results strengthen and extend the conclusion from previous studies that the time relations themselves are the primary control of rate of responding under fixed-interval schedules of reinforcement.     

Conditioned reinforcement in second-order schedules

Pigeons responded under a schedule in which food was presented only after a fixed number of fixed-interval components were completed. Two such second-order schedules were studied: under one, 30 consecutive 2-min fixed-interval components were required; under the other, 15 consecutive 4-min fixed-interval components were required. Under both schedules, when a 0.7-sec stimulus light was presented at completion of each fixed interval, positively accelerated responding developed in each component. When no stimulus change occurred at completion of each fixed interval, relatively low and constant rates of responding prevailed in each component; a similar result was obtained when a 0.7-sec stimulus change occurred at completion of each fixed interval except the one which terminated with primary reinforcement. The 0.7-sec stimulus correlated with food delivery was an effective conditioned reinforcer in maintaining patterns of responding in fixed-interval components despite low average frequencies of food reinforcement.