Delay-discounting probabilistic rewards: Rates decrease as amounts increase

The independence of delay-discounting rate and monetary reward size was tested by offering subjects (N = 621) a series of choices between immediate rewards and larger, delayed rewards. In contrast to previous studies, in which hypothetical rewards have typically been employed, subjects in the present study were entered into a lottery in which they had a chance of actually receiving one of their choices. The delayed rewards were grouped into small ($30–$35), medium ($55–$65), and large amounts ($70–$85). Using a novel parameter estimation procedure, we estimated discounting rates for all three reward sizes for each subject on the basis of his/her pattern of choices. The data indicated that the discounting rate is a decreasing function of the size of the delayed reward (p < .0001), whether hyperbolic or exponential discounting functions are assumed. In addition, a reliable gender difference was found (p = .005), with males discounting at higher rates than females, on average.     

Discounting Attributions and Multiple Determinants

The discounting principle in attribution theory was considered a well-established phenomenon until recently, when both the empirical and theoretical basis for discounting have been questioned. Many instances of strong discounting have used measures that constrain explanations, such as a forced-choice and bipolar measures. Two studies were performed simulating Thibaut and Riecken's study of attributions for target persons' compliance to a request, which used a forced-choice measure. In the present studies, a range of measures were used. Responses of two samples of Oxford students and one sample of Oxford teachers indicate that multiple causation was perceived and subjects did not greatly discount either of two relevant causes, but there was nonetheless a compensatory relation between the causes. The results also indicate that the attributions were affected by the social categories of the target person and the subjects.     

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.     

DO ADJUSTING‐AMOUNT AND ADJUSTING‐DELAY PROCEDURES PRODUCE EQUIVALENT ESTIMATES OF SUBJECTIVE VALUE IN PIGEONS?

The current experiment examined whether adjusting-amount and adjusting-delay procedures provide equivalent measures of discounting. Pigeons' discounting on the two procedures was compared using a within-subject yoking technique in which the indifference point (number of pellets or time until reinforcement) obtained with one procedure determined the value of the corresponding variable in the yoked condition with the other procedure. Behavior on each procedure was well described by a hyperbolic discounting function. Results revealed no systematic differences in the degree of discounting as measured by the discounting rate parameter of the hyperbola in Experiment 1, which used 20-mg pellets. These results were replicated in Experiment 2 using smaller, 14-mg pellets, which potentially yield more precise measurement of indifference points on the adjusting-amount procedure. The finding that estimates of the k parameter in the hyperbolic discounting function obtained with one procedure did not differ systematically from estimates obtained from the same subjects with the other procedure represents strong support for the hypothesis that the same process underlies the discounting of delayed rewards on both adjusting-amount and adjusting-delay procedures.     

环境损益的社会折扣:利他人格的影响

他人与自我之间的社会距离越远,则他人的获益或损失带给自我的效用就越小,此现象被称为社会折扣。虽然有一些研究探讨了金钱结果的社会折扣现象,但作为公共品的环境结果的社会折扣规律及其影响因素并未得到应有的研究。本研究以优劣空气天数为例,采用选择滴定程序,在损益两种情境下探索环境结果的社会折扣现象,并考察利他人格对社会折扣的影响。结果发现:(1)相比双曲模型,指数模型在损益两种情境下皆能更佳地拟合环境结果的社会折扣函数;(2)损益情境与社会距离的交互作用影响环境结果的社会折扣程度,损失情境下的社会折扣程度随社会距离的增加而变大的幅度大于收益情境;(3)利他人格在社会距离对社会折扣的影响中起调节作用。相比高利他人格者,低利他人格者的社会折扣受社会距离的影响较大。本研究对理解环境结果社会折扣和环保决策行为具有重要意义。     

Acquisition context and the use of causal rules

Judgmental asymmetries in using causal knowledge (e.g., for prediction or diagnosis) have been attributed to the inherent directionality of causal knowledge. The present study examines the effect of acquisition context--representations used for initial instruction, and the type of judgement required during acquisition--on judgments using causal rules. In contrast to traditional concept formation research, this paradigm examined the development of procedures for using rules, rather than rule induction. College-student subjects learned to use causal rules describing digital logic gates, receiving instruction with either verbal rules or truth tables, and practicing either predicting or verifying logic-gate outputs. After 200 trials of practice with each rule, subjects were transferred to the untrained judgment task. Transfer was strongly asymmetrical. Subjects trained to make prediction judgments were slowed substantially by transfer to the verification task, while subjects trained to make verification judgments had little difficulty with transfer to the prediction task. Truth-table representations resulted in superior performance, especially for verification judgments. Contrary to prediction, verification judgments always required more time. The results demonstrate that acquisition context may be partly responsible for judgmental asymmetries, and imply that examining conditions of acquisition is important for understanding how causal knowledge is used.     

Delay or probability discounting in a model of impulsive behavior: effect of alcohol

Little is known about the acute effects of drugs of abuse on impulsivity and self-control. In this study, impulsivity was assessed in humans using a computer task that measured delay and probability discounting. Discounting describes how much the value of a reward (or punisher) is decreased when its occurrence is either delayed or uncertain. Twenty-four healthy adult volunteers ingested a moderate dose of ethanol (0.5 or 0.8 g/kg ethanol: n = 12 at each dose) or placebo before completing the discounting task. In the task the participants were given a series of choices between a small, immediate, certain amount of money and $10 that was either delayed (0, 2, 30, 180, or 365 days) or probabilistic (i.e., certainty of receipt was 1.0, .9, .75, .5, or .25). The point at which each individual was indifferent between the smaller immediate or certain reward and the $10 delayed or probabilistic reward was identified using an adjusting-amount procedure. The results indicated that (a) delay and probability discounting were well described by a hyperbolic function; (b) delay and probability discounting were positively correlated within subjects; (c) delay and probability discounting were moderately correlated with personality measures of impulsivity; and (d) alcohol had no effect on discounting.     

Delay, Probability, and Social Discounting in A Public Goods Game

A human social discount function measures the value to a person of a reward to another person at a given social distance. Just as delay discounting is a hyperbolic function of delay, and probability discounting is a hyperbolic function of odds-against, social discounting is a hyperbolic function of social distance. Experiment 1 obtained individual social, delay, and probability discount functions for a hypothetical $75 reward; participants also indicated how much of an initial $100 endowment they would contribute to a common investment in a public good. Steepness of discounting correlated, across participants, among all three discount dimensions. However, only social and probability discounting were correlated with the public-good contribution; high public-good contributors were more altruistic and also less risk averse than low contributors. Experiment 2 obtained social discount functions with hypothetical $75 rewards and delay discount functions with hypothetical $1,000 rewards, as well as public-good contributions. The results replicated those of Experiment 1; steepness of the two forms of discounting correlated with each other across participants but only social discounting correlated with the public-good contribution. Most participants in Experiment 2 predicted that the average contribution would be lower than their own contribution.     

Measuring emotional management abilities: Further evidence of the importance to distinguish between typical and maximum performance

Freudenthaler and Neubauer (2005) have recently developed and validated performance measures of emotional management abilities (EMA), requiring subjects to indicate their typical behaviour in emotional situations (typical-performance instruction, TP) instead of assessing the effectiveness of different behavioural alternatives or indicating the most adequate response (maximum-performance instruction, MP). In the present study (n = 176), we examined the effects of these two instruction forms (TP vs. MP) on the EMA-scores in a between-subject design. In addition, the relations of typical and maximum EMA to cognitive intelligence components and personality traits were tested. Instruction-related comparisons of the EMA-scores yielded not only lower means but also higher standard deviations and higher reliabilities in the TP-condition. As expected, maximum EMA were significantly correlated with cognitive intelligence components but not with personality traits. In contrast, the typical EMA were moderately associated with personality traits but not related to cognitive abilities, providing further evidence of the importance to distinguish between typical and maximum performance.     

Rorschach administration: a comparison of the effect of two instructions given to an inpatient sample of drug addicts

The effect of administering the Rorschach Inkblot Method under two instructional sets was compared on three classes of outcome variables: the frequency with which subjects asked questions about the test; the frequency of brief protocols (fewer than 14 responses); and 17 traditional Rorschach structural summary scores. Sixty subjects, obtained from three inpatient psychiatric clinics treating drug addicts, randomly received either the short pre‐testing instruction “What might this be?” originally developed by Herman Rorschach and recommended in the Comprehensive System, or a longer and more elaborated instruction, which for many years has been the standard instruction in Norway. Compared with the Norwegian instruction, the short instruction produced significantly more questions to the examiner about the test. For the other outcome measures no differences were observed.     

The enduring effect of availability

The present study addressed whether experienced ease of retrieval of autobiographical events affects trait judgments made immediately and after a delay (Experiment 1) and whether this influence is modulated by either of two discounting instructions (Experiment 2). In Experiment 1, participants first attempted to retrieve 6 or 12 personal memories for different traits and then made ease of retrieval and self-trait judgments immediately or 1 week later. In Experiment 2, participants made immediate ratings and then delayed ratings under 3 instructional manipulations: a generic instruction to repeat these judgments, to make these ratings after they were reminded of their original recall total, or to make these ratings after they had their retrieval ease discounted or augmented. In each experiment, an enduring effect of availability was obtained in that the relationship between ease of retrieval and self-trait rating was only slightly affected by the delay. Being reminded of the original number of recalled memories nullified the relationship between ease of retrieval and trait rating. However, discounting or augmenting ease of retrieval, which altered ease of retrieval ratings, did not. Potential explanations for an enduring effect of availability are discussed.     

Integrated versus segregated accounting and the magnitude effect in temporal discounting

Temporal discounting rates in humans generally decrease as the amount of reward increases, a phenomenon known as themagnitude effect. In the present study, we examined whether temporal discounting and the magnitude effect are related to segregation of choices in terms of gains or losses for waiting for or expediting receipt of a reward. Subjects (N = 24) responded to a series of hypothetical choices about amounts of money available either immediately or after a delay. The immediate and delayed amounts either were presented as integrated amounts in the baseline condition or were segregated as differential gains or losses for choosing delayed or expedited consumption (delay and speedup conditions, respectively). Temporal discounting rates decreased in the segregated conditions, in accord with the standard discounted utility model but contrary to the hypothesis that the subjects were choosing on the basis of reward differentials in the baseline condition. The size of the magnitude effect was comparable in the baseline and the delay conditions but decreased in the speed-up condition. These results challenge explanations of the magnitude effect in terms of an increasing proportional sensitivity property of the utility function (Loewenstein & Prelec, 1992) and the hypothesis that subjects choose on the basis of differentials even when the rewards are presented as integrated amounts.     

Instructions as discriminative stimuli (2): A within‐subject examination of the effect of differential reinforcement on establishing novel instructional control1

Abstract: Six undergraduates were exposed to a fixed‐ratio schedule with an instruction to respond slowly and to a differential‐reinforcement‐of‐low‐rate schedule with an instruction to respond rapidly when a white circle was presented on a display monitor. When a yellow circle was presented, however, the subjects were exposed to the fixed‐ratio schedule with the instruction to respond rapidly and to the differential‐reinforcement‐of‐low‐rate schedule with the instruction to respond slowly. Following this, a fixed‐interval schedule was in effect during those stimuli and instructions. Under the white circle, response rates were higher with the instruction to respond slowly than with the instruction to respond rapidly during the fixed‐interval schedule. Such control by instructions was not observed under the yellow circle. A previous study examined establishment of novel instructional control by between‐subject comparisons and found that for three of four subjects ( Okouchi, 1999 ). In contrast, the present results demonstrate the instructional control through within‐subject comparisons for all six subjects.     

Extinction of conservation and transitivity of weight

This study attempted to determine whether children will relinquish their belief in Piagetian concepts upon presentation of disconfirming evidence. Two age groups were tested: third- and fourth-grade, and sixth-grade. Conservation of weight and transitivity of weight were the concepts examined; the discrepant feedback consisted of three trials with either non-conservation or nontransitivity outcomes. Resistance or extinction was inferred from the subject's explanations for the outcomes, his responses on subsequent trials, and his performance on a one-month delayed posttest. Conservation subjects showed only moderate resistance by any of these measures; furthermore, there was no evidence of a developmental increase in resistance. Transitivity subjects, in contrast, were much less likely than conservers to change their judgments on either the initial or the delayed test; they also showed the expected developmental increase in resistance to extinction. The results are interpreted as indicating that Piagetian concepts may vary in the extent to which they entail feelings of logical necessity.     

Examining interrelationships between the Cigarette Purchase Task and delay discounting among pregnant women

Two common behavioral economic simulation tasks used to study cigarette smoking are the Cigarette Purchase Task, a measure of cigarette demand, and delay discounting, a measure of the subjective value of rewards as a function of delays to delivery. Few studies have evaluated whether combining these tasks enhances understanding of smoking beyond either alone. The current study represents an initial evaluation of the intersection between cigarette demand indices and delay discounting among pregnant smokers by examining associations between these measures and whether a woman makes antepartum quit attempts before entering prenatal care (a reliable predictor of eventual quitting). Participants were 159 pregnant women enrolled in a smoking‐cessation trial. Low O _max and shallow discounting were each associated with antepartum quit attempts. Participants were next categorized into four subgroups (low O _max, shallow discounting; low O _max, steep discounting; high O _max, shallow discounting; high O _max, steep discounting) using median splits. Those with shallow discounting and low O _max were more likely to have made quit attempts than each of the other three subgroups. That is, steep discounting appears to undermine the association of low O _max and efforts to quit smoking during pregnancy while high O _max overshadows any protective influence associated with shallow discounting.     

Effects of inflation on the subjective value of delayed and probabilistic rewards

In the years prior to 1994, there were very high rates of inflation in Poland, and the zloty depreciated relative to the U.S. dollar. However, the new zloty, introduced in 1995, was associated with greatly decreased rates of inflation and provided a more stable currency. We report a series of three experiments that take advantage of these changes to examine the effects of inflation on the subjective value of delayed and probabilistic rewards. Subjects were Polish citizens familiar with both zlotys and dollars. The first two experiments, conducted in 1994, used dollars and old zlotys, and the third experiment, conducted in 1996, used dollars and new zlotys. In all three experiments, the dollar and zloty rewards were of equivalent worth, according to the then current exchange rates. In Experiment 1, subjects chose between immediate and delayed rewards and, in Experiment 2, chose between certain and probabilistic rewards. The subjective value of a delayed reward was greater when its amount was specified in dollars than when it was specified in old zlotys. In contrast, the currency in which a reward was specified had no effect on the subjective value of probabilistic rewards. The results of these two experiments suggest a selective effect of inflation on decisions involving delayed rewards. This was verified in the third experiment, in which, using new zlotys, no differences in discounting were observed between the two currencies with either probabilistic or delayed rewards. Importantly, in all three experiments, the discounting of both delayed and probabilistic rewards was well described by the same simple mathematical model, suggesting that similar decision-making processes underlie both phenomena. However, the present results argue against a single-process theory in which the discounting of probabilistic rewards is derived from the discounting of delayed rewards.     

Intentional faking of the single category Implicit Association Test and the Implicit Association Test

The Implicit Association Test (IAT) provides a relative measure of implicit association strengths between target and attribute categories. In contrast, the Single Category Implicit Association Test (SC-IAT) measures association strength with a single attribute category. This can be advantageous if a complementary category--as used in the IAT--cannot be composed or is undesired. If the SC-IAT is to be a meaningful supplement to the IAT, it should meet the same requirements. In an online experiment with a large and heterogeneous sample, the fakability of both implicit measures was investigated when measuring anxiety. Both measures were fakable through specific instruction (e.g., "Slow down your reactions") but unfakable through nonspecific faking instruction even though nonspecific instruction was given immediately before the critical blocks (e.g., "Alter your reaction times"). When comparing the methodological quality of both implicit measures, the SC-IAT had lower internal consistency than the IAT. Moreover, with specific faking instructions, the SC-IAT was possible to fake to a larger extent than the IAT.     

Conditioned Reflex and Perception: The Concept of Syncretism

Delay discounting occurs when the subjective value of an outcome decreases because its delivery is delayed. Past research has shown that how steeply participants discount an outcome varies inversely with the value of previously discounted outcomes. In the present study, participants discounted the same hypothetical monetary outcome ($1,000) after their hypothetical annual income was halved (Experiment 1) or doubled (Experiment 2). Rates of discounting decreased and increased, respectively, after these manipulations (although a similar change in discounting was observed for the control and treatment groups in Experiment 2). These results suggest that altering the context in which the discounting task is framed alters the subjective value of the outcome itself, in this case money. This result has implications for understanding contrast effects that are observed in rates of discounting, as well as for researchers and practitioners who are interested in determining methods for altering how individuals discount delayed outcomes.     

SAVING THE BEST FOR LAST? A CROSS-SPECIES ANALYSIS OF CHOICES BETWEEN REINFORCER SEQUENCES

Two experiments were conducted to compare choices between sequences of reinforcers in pigeon (Experiment 1) and human (Experiment 2) subjects, using functionally analogous procedures. The subjects made pairwise choices among 3 sequence types, all of which provided the same overall reinforcerment rate, but differed in their temporal patterning. Token reinforcement schedules were used in both experiments and the type of exchange schedule varied across blocks of sessions. Some conditions permitted immediate exchange of tokens for consumable reinforcers (food for pigeons, video access for humans); in other conditions, tokens accumulated and were exchanged for consumable reinforcers only at the end of the sequence. Choice patterns in the immediate-exchange conditions were generally similar across species, with both pigeons and humans preferring sequences with the shortest delay to the initial reinforcer in the series. The results are broadly consistent with models of temporal discounting expanded to include the impact of sequences of delayed reinforcers acting in parallel from the time of the choice. Preferences were less consistent with discounting models in the delayed exchange conditions. Questionnaire data gathered at the end of the experiment were consistent with prior results of questionnaire studies, but showed no straightforward relation to the observed choice patterns, urging caution in the extrapolation of results from one decision-making domain to the other.