The Impact of Experiencing Outcomes on Delay and Probability Discounting

<p>Temporal and probability discounting refer to the decrease in subjective value of rewards that are either delayed or uncertain. Comparatively high degrees of discounting have been linked to other indices of impulsivity in both animals and humans, but the study of human discounting has primarily relied on participant reports of preferences between hypothetical outcomes. A number studies to date have illustrated not only how sensitive these preferences are to manipulations within such hypothetical procedures, but also that tasks where each consequence is actually experienced are able to capture changes in behaviour that hypothetical tasks may not. The current thesis examined temporal and probability discounting using a novel experiential discounting task in the form of a computer game-based discounting task in which the delays or probabilities of the preferred outcomes were experienced following each choice. The game had participants collect points by skiing over jumps, and discounting choices between either immediate and delayed or certain and uncertain point outcomes provided additional opportunities for point gain. Discounting was examined across four samples primarily composed of university students. Experiment 1, a test of the newly created task in two parts, assessed the most appropriate descriptive model of both temporal and probability discounting, as well as examined the relation between the two, hypothetical discounting and self-report measures of impulsivity and risk taking. Experiment 2 examined the effect of magnitude manipulations on both temporal and probability discounting. Experiment 3 examined the effect on degree of temporal discounting of manipulations to post-reward delays and access to alternative reinforcement during this period. Lastly, Experiment 4 attempted to manipulate the association between delay and risk and examined the impact of this on discounting of delayed outcomes. Participants across all studies showed systematic decreases in subjective value of both delayed and uncertain point outcomes. However, the shape of this decrease in value differed across the two types of outcomes, as did the effect of the magnitude manipulations. Furthermore, neither post-reinforcement duration, access to alternative reinforcement, nor experience with risk influenced degree of temporal discounting. The results are discussed in terms of single process accounts of discounting, the implications for individual trait interpretations of discounting and the relevance of experiential and hypothetical discounting to the construct of impulsivity.</p>

The Impact of Experiencing Outcomes on Delay and Probability Discounting

<p>Temporal and probability discounting refer to the decrease in subjective value of rewards that are either delayed or uncertain. Comparatively high degrees of discounting have been linked to other indices of impulsivity in both animals and humans, but the study of human discounting has primarily relied on participant reports of preferences between hypothetical outcomes. A number studies to date have illustrated not only how sensitive these preferences are to manipulations within such hypothetical procedures, but also that tasks where each consequence is actually experienced are able to capture changes in behaviour that hypothetical tasks may not. The current thesis examined temporal and probability discounting using a novel experiential discounting task in the form of a computer game-based discounting task in which the delays or probabilities of the preferred outcomes were experienced following each choice. The game had participants collect points by skiing over jumps, and discounting choices between either immediate and delayed or certain and uncertain point outcomes provided additional opportunities for point gain. Discounting was examined across four samples primarily composed of university students. Experiment 1, a test of the newly created task in two parts, assessed the most appropriate descriptive model of both temporal and probability discounting, as well as examined the relation between the two, hypothetical discounting and self-report measures of impulsivity and risk taking. Experiment 2 examined the effect of magnitude manipulations on both temporal and probability discounting. Experiment 3 examined the effect on degree of temporal discounting of manipulations to post-reward delays and access to alternative reinforcement during this period. Lastly, Experiment 4 attempted to manipulate the association between delay and risk and examined the impact of this on discounting of delayed outcomes. Participants across all studies showed systematic decreases in subjective value of both delayed and uncertain point outcomes. However, the shape of this decrease in value differed across the two types of outcomes, as did the effect of the magnitude manipulations. Furthermore, neither post-reinforcement duration, access to alternative reinforcement, nor experience with risk influenced degree of temporal discounting. The results are discussed in terms of single process accounts of discounting, the implications for individual trait interpretations of discounting and the relevance of experiential and hypothetical discounting to the construct of impulsivity.</p>

PERENCANAAN ULANG BANGUNAN PENGAMBILAN BERTIPE MORNING GLORY MENGGUNAKAN PONDASI BORED PILE PADA BENDUNGAN LOGUNG

The existing square tower of intake has 1,397.57m3 volume and using shallow foundation Logung Dam with its weight stability will cause inefficient structures and potential to earthquake force effect. It is necessary to have an alternative planning of the intake tower. The authors intends to redesign the intake with morning glory type and used bored pile; to find out the position of intake tower, dimension, reinforcement, duration, cost estimate, and to compare the redesign.The required data were of topographic map, irrigation, and raw water discharge, bearing capacity, and work unit price analysis of project 2016. Manning Method was applied to find out the dimension; Shell Slab Method with Column Approach to calculate the structure of the intake tower, and Skempton Method to calculate bearing capacity. The redesign results in the position of ∅ 1.75-m intake tower on conduit channel with 728,08 m3 volume; the dominant load of operational-earthquake combination with different values; D22-200 steel bar for y-direction, D19-150 for x-direction on conduit channel, D19-150 for x,y-direction on intake tower segment 1, D16-150 for x,y-direction on intake tower segment 2, and D13-150 for x,y-direction on intake tower segment 3; on 105 workdays; at a total cost of IDR 2,327,806,700 with 40.64 % efficiency cost.

Duration of wheel-running reinforcement: Effects on reinforcement value and motivation in free-feeding and food-deprived rats.

Ten (pair housed) female Long-Evans rats were exposed to 5 s, 30 s, and 90 s wheel-running reinforcement durations on a response-initiated variable interval 20 s schedule as food deprivation was manipulated. On free feeding, never-deprived rats showed low wheel running and lever-pressing rates with long postreinforcement pauses (PRPs) for the 5-s reinforcement duration. Subsequently, when food deprived (Deprived 1), rats showed no effect of reinforcement duration on all measures. Under a second deprived condition (Deprived 2) with the rats maintained in single cages, there was no effect of housing (single vs. paired). When data from both deprivation assessments (Deprived 1 and Deprived 2) were combined, rats showed lower wheel running and overall lever-pressing rates with longer pauses on the 90-s duration compared to 30 s and 5 s bouts of wheel activity. The pattern of results challenges a reinforcement value interpretation, but is consistent with shifts in the motivational basis of wheel running. On free feeding, never-deprived rats were intrinsically motivated to run on wheels and operant lever-pressing was maintained at moderate rates by the automatic reinforcement of wheel running, except at the short reinforcement duration (5 s). When food deprived, motivation became food-related and rats showed high rates of lever pressing even at the shortest duration. The weak effects under initial deprivation (Deprived 1) raise questions about equivalence between wheel-running reinforcement duration and reinforcement magnitude using food reinforcement.