This article reviews the literature on magnitude of unconditioned reinforcement (including duration, volume, and percentage concentration methods of programming magnitude). Debate continues over whether manipulation of reinforcement magnitude influences behavior. Although some studies (particularly those involving choice contingencies) demonstrate magnitude effects, others do not. These contradictory findings are discussed here in terms of the necessary and sufficient conditions for producing a reinforcement magnitude effect. Also, the ability of various theories to account for various magnitude effects is discussed. It is suggested that future research take a more systematic direction, uncovering the necessary and sufficient conditions for producing an effect and expanding and testing theories.One parametric variable that presumably modulates the effect of reinforcement on behavior is the magnitude of reinforcement. The term magnitude of reinforcement, as it is variously used in the literature, refers to the amount (volume) of reinforcement, such as the number of pellets (Keesey & Kling,

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On a multiple fixed-ratio 10 fixed-ratio 100 schedule, pigeons pause for relatively long periods of time before the fixed-ratio 100 schedule. Only a short pause occurs before the fixed-ratio 10 schedule. A chain fixed-ratio 10 fixed-ratio 100 schedule produces the reverse pattern, i.e., a short pause before the fixed-ratio 100 schedule and a long pause before the fixed-ratio 10 schedule. Procedurally, the only difference between the two schedules is that the fixed-ratio 10 component is always terminated by some unconditioned reinforcer in the multiple schedule but never in the chained schedule. In the present experiment, the percentage of fixed-ratio 10 components which included reinforcement was gradually decreased for birds on the multiple schedule and gradually increased for birds on the chained schedule. It was found that percentage reinforcement within the fixed-ratio 10 component was inversely related to the duration of the pause before the fixed-ratio 10 component and directly related to the duration of the pause before the fixed-ratio 100 component. Thus, the relative rate of reinforcement paired with a particular stimulus was seen to be an important factor in determining response latency to that stimulus.

A change in the size of a fixed-ratio schedule involves a simultaneous change in number of responses, in time to complete the ratio (work time), and in the interval between successive reinforcements (interreinforcement interval). Previous studies have suggested the importance of work time and the interreinforcement interval in controlling the length of the post-reinforcement pause. The present study sought to determine whether number of responses is also a significant factor. Pigeons were trained on a multiple fixed-ratio x fixed-ratio 2 plus timeout schedule in which the size of the fixed-ratio x was manipulated. When the work times (Experiment I) or interreinforcement intervals (Experiment II) were equated for the two components, the pause before the fixed-ratio x was longer than the pause before the fixed-ratio 2 plus timeout. As fixed-ratio x size increased, the relative difference in the lengths of the two types of pauses also increased. Because the fixed-ratio x component contained a larger number of responses than the fixed-ratio 2 plus timeout component, the relatively longer pause preceding the fixed-ratio x indicates that number of responses played a significant role in determining the length of the post-reinforcement pause.

Previous research has suggested that there are stimuli in the environment that can influence the amount of litter discarded in that environment. This experiment investigated the effects of litter already present within an area on littering behavior in a forest setting. The study was conducted for a period of four successive Fridays. The first and third Fridays were used to obtain an estimate of the amount of litter that accumulated after the areas were cleaned of litter (the nonlittered condition). During the second and fourth Fridays all litter was removed from the area, then 60 pieces of litter were scattered throughout the picnic site (the littered condition). The number of pieces of litter was counted each Saturday morning. The amount of litter found on Saturday mornings following a littered condition was always less than the amount of litter found following a nonlittered condition. In those areas which were littered, people had a tendency not to discard additional litter.