Discounting of delayed rewards in opioid-dependent outpatients: Exponential or hyperbolic discounting functions?

Recent theories of substance abuse have used value discounting of delayed rewards to partly explain the decision to take drugs. Normative-economic theory holds that an exponential function describes the effects of delay on discounting, whereas the matching law posits a hyperbolic discounting function. The ability of these functions to describe 18 human heroin-dependent individuals' monetary- and heroin-reward delay-discounting functions was assessed. In the 1st condition, participants chose between immediate and delayed hypothetical monetary rewards. Delayed rewards were $1,000, and the immediate reward amount was adjusted until choices reflected indifference. In the 2nd condition, participants chose between immediate and delayed heroin (the delayed amount was that which each participant reported he or she could purchase with $1,000). The hyperbolic function produced significantly higher R2 values and significantly lower sums of squared error values. Consistent with previous findings, delayed heroin rewards were discounted at a significantly higher rate than were delayed monetary rewards. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information processing and the development of cooperative, competitive, and individualistic social values.

109 3–10 yr old Ss completed an individualized regression assessment of social values, a central-incidental memory measure, and a free-recall word list task in a study that assessed the possibility that the developmental difference in social values is associated with the development of information-processing capabilities. Findings demonstrate developmental differences in social values and suggest a possible partial explanation for the differences. The modal social value among 3–5 yr olds was individualism, while among 6–7 yr olds and 8–20 yr olds the modal social value was superiority. The oldest Ss expressed a social value involving equality more frequently than did younger Ss. It is suggested that older children, compared to younger children, more often consider the relative nature of their outcomes and more often engage in social comparison. Performance on the memory tasks was consistently associated with age: Ss who expressed an individualism social value generally performed more poorly on the memory measures than did Ss who expressed any other social value. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in responses to a television character's appearance and behavior.

In a 2?×?2?×?3 design, 52 3–5 yr olds, 58 6–7 yr olds, and 59 9–10 yr olds viewed a videotape in which a female protagonist's appearance (attractive, ugly) was factorially varied with her behavior (kind, cruel). Perceptions of the protagonist and predictions of the story's outcome were assessed. Based on theoretical and empirical evidence of a developmental decrease in perceptual dependence, the influence of the woman's appearance was expected to decrease with age, and the influence of her behavior was expected to increase with age. These expectations were confirmed. A 2nd study was conducted with 40 4–5 yr olds, 41 6–7 yr olds, and 34 9–21 yr olds to rule out the alternative explanation that younger children possess stronger physical appearance stereotypes than do older children. In this study, Ss did not have information about the woman's behavior. It was found that Ss at all 3 age levels demonstrated appearance stereotyping. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Notational adaptation in children.

Three experiments examined whether and how children adapt their notations (use of external symbol systems) to the communicative needs of addresses of different ages. In Exp 1, 26 8–9 yr olds, 28 10–11 yr olds, and 11 adults made 2 notations about a solution to a simple board puzzle, one for a peer and the other for a 6-yr-old. Exp 2, with 28 8–9 yr olds, 23 10–11 yr olds, and 30 adults, focused on oral adaptations in the same context. In Exp 3, 28 8–9 yr-olds, 21 10–11 yr olds, and 30 adults were asked to choose ready-made notations for different addresses. Children's notations at both age groups were overall informative and adequate and improved with age. Children's notation's however, were not as sophisticated as verbal instructions, possible due to the Ss' more extensive experience with oral communication. Children's notational adaptation also developed with age. Some 8–9 yr olds and many 10–11 yr olds made systematic changes in their notations and verbal instructions for addresses of different ages. Most Ss of both age groups were aware of the difference in communicative competence between the younger addressee and the peer. They also shared with adults certain assumptions regarding the needs of the younger addresses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of cognitive interviewing and practice on children's recall performance.

In Exp 1, a staged event was carried out that involved a private encounter between an unfamiliar man and 2 children. The results show that questioning techniques based on principles from cognitive psychology significantly increased the number of correct facts recalled by both 7–8 yr olds and 10–11 yr olds over that gained with standard interview procedures and without affecting the number of incorrect items generated. These results were replicated in Exp 2 with a different staged event and with 8–9 yr olds and 11–12 yr olds. Exp 2 also assessed the impact of a prior practice cognitive interview, and practice was found to be effective for both age groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Septal lesions and incentive expectancies in rats.

Tested male albino Wistar rats with bilateral septal lesions on a multiple DRL schedule with large and small rewards. The lesion produced less efficient DRL performance under both conditions. Small rewards produced more efficient DRL responding in controls and brain-damaged Ss. A 2nd study investigated runway conditioning under immediate, delayed, and no reward. Septal lesions increased running speeds with immediate reward, maintained faster speeds during the early delayed-reward trials, but produced no differences during extinction. A 3rd experiment investigated the effects of immediate and delayed rewards on auditory discrimination learning in septal and control Ss. Brain-damaged Ss showed inferior discrimination performance with delayed rewards but not with immediate rewards. Data suggest that septal lesions alter cognitive strategies (i.e., expectancies) based on incentive characteristics. (French abstract) (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Children's concepts of volume and flotation.

Conducted a pilot study in which children (aged 7–9 yrs and 11–13 yrs) were asked to judge which 1 out of 3 wooden blocks would float (or sink), given weight and volume information for each block relative to a block that was known to float (or sink). Analysis of explanations indicated that judgments may have been based on the size–weight illusion. An experiment exploring the basis of flotation judgments was conducted with 14 children aged 7 yrs 1 mo to 9 yrs 6 mo and 16 children aged 11 yrs 4 mo to 14 yrs 11 mo that involved a test for judgment of volume based on information integration theory. Results show that Ss aged 7–24 yrs accurately judged volume by integrating 3 dimensions—width, depth, and height—according to the multiplicative rule. A rule assessment of their flotation judgments showed no age differences in initial rule, with weight rules being most popular. However, after feedback there were marked age effects; the 7–9 yr olds abandoned their initial rule without finding an alternative, and the 11–24 yr olds were generally able to find the correct flotation rule. It is concluded that children aged 7–24 yrs can judge volume but 7–9 yr olds have difficulty with the concept of flotation, possibly because it requires mental comparison of 2 ratios, a task known to be difficult for 7–9 yr olds. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive mood effects on delay discounting.

Delay discounting is the process by which the value of an expected reward decreases as the delay to obtaining that reward increases. Individuals with higher discounting rates tend to prefer smaller immediate rewards over larger delayed rewards. Previous research has indicated that personality can influence an individual's discounting rates, with higher levels of Extraversion predicting a preference for immediate gratification. The current study examined how this relationship would be influenced by situational mood inductions. While main effects were observed for both Extraversion and cognitive ability in the prediction of discounting rates, a significant interaction was also observed between Extraversion and positive affect. Extraverted individuals were more likely to prefer an immediate reward when first put in a positive mood. Extraverts thus appear particularly sensitive to impulsive, incentive-reward-driven behavior by temperament and by situational factors heightening positive affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observing response acquisition: Preference for unpredictable appetitive rewards obtained under conditions predicted by DMOD.

To investigate the preference for unpredictable rewards predicted by the present author and J. T. Daly's (see record 1983-20275-001) modification, known as the DMOD model, of R. A. Rescorla and A. R. Wagner's (1972) previous model of reinforcement, the present author conducted 5 E-maze experiments with 144 male Holtzman rats. In Exps I–V, Ss were given a choice between receiving reward and nonreward in a situation in which stimuli were correlated with reward outcome (predictable situation) vs a situation in which the stimuli were uncorrelated with reward outcome (unpredictable situation). Preference for the unpredictable situation occurred under the following conditions: small (1 37-mg pellet) immediate rewards, small delayed (15-sec) rewards when the cues correlated with reward outcome were absent during the delay interval, large (15 pellets) immediate rewards when a difficult discrimination was required, and when the stimulus predicting nonreward was present at the choice point. Preference for the predictable situation was strongest if reinforcement was delayed and large or if the stimulus predicting reward was present at the choice point. A weaker preference for the predictable situation occurred if reinforcement was immediate, large, and required a simple discrimination or if reinforcement was large and delayed and the cues that correlated with reward outcome were absent during the delay interval. Findings support the predictions of the DMOD model of appetitive learning. (33 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Self-administered cocaine causes long-lasting increases in impulsive choice in a delay discounting task.

Cocaine use is associated with high levels of impulsive choice (preference for immediate over delayed rewards), but it is not clear whether cocaine use causes elevated impulsive choice, or whether elevated impulsive choice is solely a predisposing factor for cocaine use. This study examined the effects of prior cocaine self-administration on rats performing a delay discounting task commonly used to measure impulsive choice. Male Long-Evans rats were implanted with intravenous catheters, and following recovery, were trained to self-administer 30 mg/kg/day cocaine HCl (approx. 0.5 mg/kg/infusion) for 14 consecutive days (a control group received yoked intravenous saline infusions). Following three weeks of withdrawal, all rats were food-restricted and began training on the delay discounting task in standard operant chambers. On each trial, rats were given a choice between two levers. A press on one lever delivered a small food reward immediately, and a press on the other delivered a large food reward after a variable delay period. Rats that self-administered cocaine displayed greater impulsive choice (enhanced preference for the small immediate over the large delayed reward, as reflected by shorter indifference points) compared to controls, but were no different from controls on a “probabilistic discounting” task in which they chose between small certain and large uncertain rewards. These data suggest that self-administered cocaine can cause lasting elevations in impulsive choice, and that the high levels of impulsive choice observed in human cocaine users may be due in part to long-term effects of cocaine on brain function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alcohol demand, delayed reward discounting, and craving in relation to drinking and alcohol use disorders.

A behavioral economic approach to alcohol use disorders (AUDs) emphasizes both individual and environmental determinants of alcohol use. The current study examined individual differences in alcohol demand (i.e., motivation for alcohol under escalating conditions of price) and delayed reward discounting (i.e., preference for immediate small rewards compared to delayed larger rewards) in 61 heavy drinkers (62% with an AUD). In addition, based on theoretical accounts that emphasize the role of craving in reward valuation and preferences for immediate rewards, craving for alcohol was also examined in relation to these behavioral economic variables and the alcohol-related variables. Intensity of alcohol demand and delayed reward discounting were significantly associated with AUD symptoms, but not with quantitative measures of alcohol use, and were also moderately correlated with each other. Likewise, craving was significantly associated with AUD symptoms, but not with alcohol use, and was also significantly correlated with both intensity of demand and delayed reward discounting. These findings further emphasize the relevance of behavioral economic indices of motivation to AUDs and the potential importance of craving for alcohol in this relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Choosing problem-solving rewards and Halloween prizes: Delay of gratification and preference for symbolic reward as a function of development, motivation, and personal investment.

Conducted 3 experiments to generate and cross-validate a developmental account of reward preferences in the lifelike condition in which available rewards differ on both the immediate-delayed and material-symbolic dimensions. 429 children within a broad range of developmental levels (CA 2?–20 yrs) selected from arrays in which immediate-material, immediate-symbolic, delayed-material, and delayed-symbolic items were available. In each experiment more mature Ss delayed gratification to maximize reward magnitude and chose rewards symbolic of success more often than did less mature Ss. Analyses indicated that the 2 reward dimensions were both highly salient in Ss' thinking and that developmental effects on the 2 dimensions could be neatly integrated within a 3-stage developmental scale. Developmental effects on this scale and on the separate dimensions persisted across changes in the particular reward items available and changes in location from school testing room to more naturalistic Halloween settings. Findings indicate that preference for symbolic rewards tends to be more pronounced among the mentally retarded than the nonretarded but cast doubt upon previous interpretations of that group difference. Finally, children's Halloween prize choices suggested that preference for symbolic reward is a function of one's developmental level, the achievement being rewarded, and the extent of one's personal investment in that achievement. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pathological gamblers, with and without substance abuse disorders, discount delayed rewards at high rates.

Pathological gambling is classified as a disorder of impulse control, yet little research has evaluated behavioral indices of impulsivity in gamblers. The rates at which rewards delayed in time are subjectively devalued may be a behavioral marker of impulsivity. This study evaluated delay discounting in 60 pathological gamblers and 26 control participants. Gamblers were divided into those with (n?=?21) and without (n?=?39) substance use disorders. A hypothetical $1,000 reward was delayed at intervals ranging from 6 hr to 25 years, and immediate rewards varied from $1 to $999. Pathological gamblers discounted delayed rewards at higher rates than control participants, and gamblers with substance use disorders discounted delayed rewards at higher rates than non-substance-abusing gamblers. These data provide further evidence that rapid discounting of delayed rewards may be a feature central to impulse control and addictive disorders, including pathological gambling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search for features and conjunctions in development.

Visual search performance was examined in 24 7–8 yr olds, 22 9–10 yr olds, 15 11–12 yr olds, and in 10 young adults (aged 23–30 yrs). Color and orientation feature searches and a conjunction search were conducted. Reaction time (RT) showed expected improvements in processing speed with age. Comparisons of RTs on target-present and target-absent trials were consistent with parallel search on the 2 feature conditions and with serial search in the conjunction condition. The RT results indicate that searches for feature arid conjunctions were treated similarly for children and adults. However, the youngest children missed more targets at the largest array sizes, most strikingly in conjunction search. Based on an analysis of speed/accuracy trade-offs, we suggest that low target-distractor discriminability leads to an undersampling of array elements, and is responsible for the high number of misses in the youngest children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of age and sex on responsiveness to babies.

Interest in babies was assessed in 32 8–9 yr olds and 32 14–15 yr olds by 6-sec time sampling of waiting room behaviors in the presence of a live baby and by reactions to pictures of babies vs other objects. Age conferred mode differences in behavioral responsivity: Adolescents made more proximal bids, 8–9 yr olds more distal bids. Males and females differed in amount of behavioral and perceptual baby interest, with girls more responsive than boys. Sex differences were virtually absent among 8–9 yr olds but emerged during adolescence. Interpretations in terms of increased salience of sex-role stereotypes during adolescence are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal horizons in decision making.

The perception of duration is crucial when we make choices between immediate and delayed rewards. Immediate rewards are valued more than the same rewards if they are delayed. Preferences for earlier rewards become even stronger when the reward can be received within a subjectively proximate time frame. A “rational” decision to wait for a delayed reward may be overruled by an “impulsive” choice when the option for the closer reward falls within this proximate time range. Based on findings on circadian and circannual physiological rhythms, we suggest that there are 2 time units that are both biologically and culturally determined and have an impact on human experience and behavior: the day and the year. We highlight results of a neuroimaging study showing that rewards with delays up to 1 year are discounted differently than reward delays longer than 1 year. This duration-dependent discounting is associated with specific brain activation in the striatum. We present various conceptualizations of subjective time incorporated in parametric models of intertemporal decisions that may lead to a better understanding of human choice behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impulsive and self-control choices in opioid-dependent patients and non-drug-using control patients: Drug and monetary rewards.

Delay discounting was investigated in opioid-dependent and non-drug-using control participants. The latter participants were matched to the former on age, gender, education, and IQ. Participants in both groups chose between hypothetical monetary rewards available either immediately or after a delay. Delayed rewards were $ 1,000, and the immediate-reward amount was adjusted until choices reflected indifference. This procedure was repeated at each of 7 delays (1 week to 25 years). Opioid-dependent participants were given a second series of choices between immediate and delayed heroin, using the same procedures (i.e., the amount of delayed heroin was that which could be purchased with $1,000). Opioid-dependent participants discounted delayed monetary rewards significantly more than did non-drug-using participants. Furthermore opioid-dependent participants discounted delayed heroin significantly more than delayed money. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of the goal on children's exploration and memory of large-scale space.

Investigated developmental differences in spatial exploration and memory depending on the purpose for which 32 6–7 and 8–9 yr olds explored the space. Ss were instructed prior to exploring a funhouse to attend to either the layout of the space or the route through the space. Ss given instructions to study the layout studied and remembered more layout-relevant information, such as the number and location of dead-end rooms and the relations between spatial features, than did those in the route condition; this same pattern was found for the 6–7 and the 8–9 yr olds. Results suggest that layout knowledge includes knowledge of routes, that layout rather than route knowledge emphasizes the interrelationship of spatial information, and that the acquisition of route or layout knowledge depends on the purpose of obtaining the information. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The young child's understanding of communication.

Conducted 2 experiments with 110 5-8 yr olds to investigate the extent to which the young child understands that messages can be inadequate to determine whether there is a developmental trend in such understanding. Each child played the role of both speaker and listener in a communication game with the E. Failures in communication were made to occur, and the child was asked to judge whose fault these were and why. In Exp I, a significant age-related trend was found: almost all 5.5-6 yr olds located the fault with the listener; the 6.5-7 yr olds most frequently blamed the E (who was a speaker for half of the trials); blaming the speaker alone was most common in the 7.5-8 group. Results suggest that the older children, but not the youngest, understood that communication failure can be occasioned by an inadequate message. The existence of children who always blamed the E and the failure to find any who always blamed themselves were confirmed in Exp II with different materials. These findings cast doubt upon the accuracy of Piaget's (1959) account of the breakdown of egocentrism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vibration as positive reinforcement for retarded children.

Contends that previous studies investigating vibration as a positive reinforcer did not provide: adequate controls for touch and noise; a sufficient number of Ss; or comparisons of vibration with other reinforcers. In the present study, 4 groups of 40 trainable, institutionalized, retarded 8-12 yr. olds were exposed to an operant button-pressing paradigm. Results indicate that vibration compared favorably with a food reinforcer and that vibration was significantly more effective as a reward than the touch or the noise emitted by the vibrator. It is suggested that vibration may be used as an effective reinforcer to train retarded children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)