Delay discounting of different outcomes: Review and theory

Steep delay discounting is characterized by a preference for small immediate outcomes relative to larger delayed outcomes and is predictive of drug abuse, risky sexual behaviors, and other maladaptive behaviors. Nancy M. Petry was a pioneer in delay discounting research who demonstrated that people discount delayed monetary gains less steeply than they discount substances with abuse liability. Subsequent research found steep discounting for not only drugs, but other nonmonetary outcomes such as food, sex, and health. In this systematic review, we evaluate the hypotheses proposed to explain differences in discounting as a function of the type of outcome and explore the trait- and state-like nature of delay discounting. We found overwhelming evidence for the state-like quality of delay discounting: Consistent with Petry and others' work, nonmonetary outcomes are discounted more steeply than monetary outcomes. We propose two hypotheses that together may account for this effect: Decreasing Future Preference and Decreasing Future Worth. We also found clear evidence that delay discounting has trait-like qualities: People who steeply discount monetary outcomes steeply discount nonmonetary outcomes as well. The implication is that changing delay discounting for one outcome could change discounting for other outcomes.     

大学生未来取向与学习自主性的关系研究:学业延迟满足和时间管理倾向的多重中介作用

本研究旨在探讨未来取向和学习自主性的关系,分析学业延迟满足、时间管理倾向的作用.采用问卷法对731名大学生进行调查,研究表明:(1)大学生未来取向、学业延迟满足、时间管理倾向和学习自主性之间均存在显著相关;(2)大学生学业延迟满足、时间管理倾向在未来取向和学习自主性间存在中介效用,即未来取向直接影响大学生的学习自主性,...     

DELAY‐AMOUNT TRADEOFFS IN CHOICES BY PIGEONS AND RATS: HYPERBOLIC VERSUS EXPONENTIAL DISCOUNTING

An adjusting‐delay procedure was used to study the choices of pigeons and rats when both delay and amount of reinforcement were varied. In different conditions, the choice alternatives included one versus two reinforcers, one versus three reinforcers, and three versus two reinforcers. The delay to one alternative (the standard alternative) was kept constant in a condition, and the delay to the other (the adjusting alternative) was increased or decreased many times a session so as to estimate an indifference point—a delay at which the two alternatives were chosen about equally often. Indifference functions were constructed by plotting the adjusting delay as a function of the standard delay for each pair of reinforcer amounts. The experiments were designed to test the prediction of a hyperbolic decay equation that the slopes of the indifference functions should increase as the ratio of the two reinforcer amounts increased. Consistent with the hyperbolic equation, the slopes of the indifference functions depended on the ratios of the two reinforcer amounts for both pigeons and rats. These results were not compatible with an exponential decay equation, which predicts slopes of 1 regardless of the reinforcer amounts. Combined with other data, these findings provide further evidence that delay discounting is well described by a hyperbolic equation for both species, but not by an exponential equation. Quantitative differences in the y‐intercepts of the indifference functions from the two species suggested that the rate at which reinforcer strength decreases with increasing delay may be four or five times slower for rats than for pigeons.     

EVALUATION OF AN ENHANCED STIMULUS‐STIMULUS PAIRING PROCEDURE TO INCREASE EARLY VOCALIZATIONS OF CHILDREN WITH AUTISM

Evidence to support stimulus‐stimulus pairing (SSP) in speech acquisition is less than robust, calling into question the ability of SSP to reliably establish automatically reinforcing properties of speech and limiting the procedure's clinical utility for increasing vocalizations. We evaluated the effects of a modified SSP procedure on low‐frequency within‐session vocalizations that were further strengthened through programmed reinforcement. Procedural modifications (e.g., interspersed paired and unpaired trials) were designed to increase stimulus salience during SSP. All 3 participants, preschoolers with autism, showed differential increases of target over nontarget vocal responses during SSP. Results suggested an automatic reinforcement effect of SSP, although alternative interpretations are discussed, and suggestions are made for future research to determine the utility of SSP as a clinical intervention for speech‐delayed children.     

个体与群体情境下3～5岁幼儿延迟满足的实验研究

采用实验法以90名3~5岁的儿童为被试,探讨其在个体和群体情境中延迟满足的特点。研究结果表明:3~5岁幼儿的延迟满足能力存在着显著的年龄差异,随着年龄的增长而不断提高;3岁幼儿延迟满足能力较弱,而4、5岁的幼儿在这种能力上有了较明显的发展,但从整体上来看,幼儿阶段的延迟满足能力仍然很低;3~5岁幼儿的延迟满足能力在不同的情境、不同性别中不存在显著的差异。     

Reformative self‐control and discounting of reward value by delay or effort1

Abstract: The relation between reformative self‐control and discounting of reward value by delay or effort was examined. Thirty‐two Japanese undergraduates were selected based on their scores on a standardized pencil and paper test of self‐control, the Redressive–Reformative Self‐Control Scale ( Sugiwaka, 1995 ). The subjects indicated their preference (i) between a hypothetical 100 000 yen reward available with various delays and a certain reward of variable amount available immediately; or (ii) between a hypothetical 100 000 yen reward available with various efforts and a certain reward of variable amount available without effort. The discounting of delayed reward value was described well by a hyperbolic function proposed by Mazur (1987 ). The slopes of the delayed discounting curves were steeper for subjects who scored low on the Reformative Self‐Control Scale, which is a measure of reformative self‐control and a subscale of the Redressive–Reformative Self‐Control Scale. The discounting by effort was also described well by the hyperbolic function. The slopes of the effortful discounting curves did not correlate to those of the delayed discounting curves. The slopes were not systematically different across the groups of subjects with different scores on the reformative self‐control scale.     

因果错觉的实验研究

本研究分别从可控情境和不可控情境两方面探讨了在工具性条件反射中,人对因果关系的认知的特点。结果发现：1．在可控情境下。延迟反馈可能导致被试的因果错觉;2、在不可控情境下,被试同样表现出因果错觉：迷信和控制幻觉,并且这种现象具有一定的普遍性;3、提供恰当的外部线索能有效地帮助被试消除已经形成的因果错觉。     

Response duration is sensitive to both immediate and delayed reinforcement

We investigated the duration of lever pressing by rats when the delivery of appetitive reinforcers was contingent upon response duration. In the first experiment, response durations increased when duration requirements were imposed, and they decreased when duration requirements were removed. This effect occurred whether reinforcers were immediate or delayed by 8 s. In order to maintain the integrity of the delay intervals, reinforcer delivery was dependent upon both lever depression and release. In a second experiment, lever depression only and a response duration of at least 4 s were required for reinforcer delivery. Compared to immediate reinforcement conditions, delayed reinforcers increased both variability and the length of the maximum response durations. In a third experiment, immediate reinforcers were delivered contingent upon lever depression and release under a variety of duration requirements. Median lever‐press durations tracked the contingencies rapidly. Across all three experiments, rats emitted numerous response durations that were too short to satisfy the reinforcer requirements, and bimodal distributions similar to those produced by differential reinforcement of low rate schedules were evident for most rats. In many aspects, response duration responds to reinforcement parameters in a fashion similar to rate of discrete responding, but an examination of this continuous dimension of behavior may provide additional information about environment–behavior relationships.     

Comparing rapid assessments of delay discounting with real and hypothetical rewards in children

Recent advances in assessment methodology have resulted in a highly efficient procedure for obtaining delay discounting rates for adults: a 5‐trial adjusting delay task (ADT‐5) examining intertemporal choice for hypothetical rewards. The low participant burden of this task makes it potentially useful for children, with whom delay discounting research is relatively limited. However, it is unknown whether results from this task match choice for real rewards. The present study assessed delay discounting for real and hypothetical monetary rewards using a modified ADT‐5 with 9 children admitted to a psychiatric day treatment program. Participants completed up to 3 tasks with each reward type in alternating order. No difference in discounting rate, via log(k), was observed between the first task of each reward type. This finding was replicated across subsequent tasks for the subset of participants (n = 6) who completed all 6 tasks. However, delay discounting of real and hypothetical rewards was not found to be statistically equivalent. These results suggest that a modified ADT‐5 using hypothetical rewards may be a viable option for assessing delay discounting in children with psychiatric diagnoses, but additional research is needed to explicitly examine whether hypothetical and real rewards are discounted equivalently in this population.     

Evaluating the effect of delay spacing on delay discounting: carry‐over effects on steepness and the form of the discounting function

Most delay discounting studies use tasks that arrange delay progressions in which the spacing between consecutive delays becomes progressively larger. To date, little research has examined delay discounting using other progressions. The present study assessed whether the form or steepness of discounting varied across different delay progressions. Human participants completed three discounting tasks with delay progressions that varied in the time between consecutive delays: a standard (increasing duration between delays), linear (equal duration between delays), and an inverse progression (decreasing duration between delays). Steepness of discounting was generally reduced, and remained so, following experience with the inverse progression. Effects of the delay progression on the best fitting equation were order‐dependent. Overall the hyperbola model provided better fits, but the exponential model performed better with data from the inverse progression. Regardless, differences in which model fit best were often small. The finding that the best fitting model was dependent, in some cases, on the delay progression suggests that a single quantitative model of discounting may not be applicable to describe discounting across all procedural contexts. Ultimately, changes in steepness of discounting following experience with the inverse progression appeared similar to anchoring effects, whose mechanism will require further study to delineate.