Litter is an especially large and costly problem in unsupervised high-use recreational areas. This study investigated procedures to induce visitors to remove litter from an unsupervised U.S. Forest Service area in which signs attached to two litter stations instructed people to pick up and deposit litter. A small sum of money or chances on a larger sum given for participation usually resulted in more bags of litter being picked up per week. Although only a small proportion of the area's users participated in the project, ground surveys indicated the areas sampled were somewhat freer of litter during the payment condition. The results suggest that small monetary rewards may be a promising approach to litter control in unsupervised as well as supervised areas.

Undiscovered Recoverable Oil 36-81 Billion Barrels Undiscovered Recoverable Gas l §~ .. 5)~~ Trillion Cu Ft * Marginal Probability Applied * * For regional distribution of inferred reserves. see tables 4 and 15. FIGURE !.-Undiscovered recoverable resources of crude oil and natural gas for the United States. Report~ as a range of values at 95-5 percent probability in billions of barrels for oil and trillions of cubic feet for gas.

Fi gur e 1.-Discovered and undiscovered recoverab l e quantities of crude oi l and na t u r al ga s in the United States. Undiscovered values are mean estima t es. Crude oil in bi ll ion barrels; total natura l gas in t ri ll ion cubic fee t.

The effects of different temporal requirements in conjunctive and interlocking schedules of reinforcement were examined. The compound schedules were arranged so that a reinforcer could be delivered by either a rat's response or a clock. As the temporal requirements increased in the interlocking schedules, the overall rate of responding increased, but the pattern of responding remained relatively unchanged. As the temporal requirement increased in the conjunctive schedules, the overall rate decreased and a pause-and-run pattern of responding emerged. When the response requirement was reduced to one in the conjunctive schedule for one animal, a low and extremely stable rate of responding developed.Compound schedules of reinforcement contain a response and a time contingency (Morse, 1966). In one compound schedule, an interlocking schedule, the response requirement is maximal immediately after reinforcement and diminishes as a function of time. In another, a conjunctive schedule, the response and temporal requirements for reinforcement remain constant. Figure 1 portrays the contingencies that exist in these schedules. Two types of interlocking and two types of conjunctive schedules are illustrated using a slightly modified version of Skinner's (1958) The bottom two diagrams portray conjunctive schedules which have similar response and temporal requirements: each requires one response and 5 min for reinforcement. In the conjunctive schedule on the right, responses made before the end of the interval do not modify the response requirement. Only one response is required and it must be made after the interval has elapsed. In short, the conjunctive schedule on the right is a fixed-interval schedule of 5 min. The conjunctive schedule on the left also requires one response, but it can be made before the end of the interval, and reinforcement will occur when the interval has elapsed.Note that in the compound schedules with the dashed lines a delay between a response and reinforcement is made possible by the contingencies. In both schedules a response can be made before the end of the interval, and reinforcement will occur when the interval has elapsed, whether or not any further responding has occurred. The purpose of the present experiment was to examine a conjunctive and an interlocking schedule in which a reinforcer 579 1968, 11,[579][580][581][582][583][584][585][586] NUMBER 5 (SEPTEMBER)

Rachlin and Green (1972) proposed a model which analyzed self control as a reversal of preference for two reward values in time_ The present study investigated the utility of the model in the investigation of self-control in children. Two boys (ages 9-10) were exposed to a chain of events in which a left alternative (initial link) lead to a choice (terminal link) between a small, immediate reward (2 tokens) or a lar!!e. de laved reward (4 tokens delaved 4 sec). Equal preference was found for both left and right alternatives although once the left alternative had been selected, the immediate reward was chosen on a large percentage of the trials. However, as these choices were moved further into time, preference for the left alternative increased and the children chose the immediate reward almost exclusively. In addition, subjects spent a greater percentage of their daily tokens as time to the choice point increased. These results do not replicate Rachlin and Green's findings with pigeons. However, the subjects did show a reversal of preference as time to the choice point was manipulated, suggesting the model's utility in the investigation of self-control with humans.

No abstract

No abstract

No abstract