Valuing the future: temporal discounting of health and money

Factors affecting participation in health checkups: Evidence from Japanese survey data

Multiple factors influence individuals to get health checkups. This study investigates key determinants of the health checkup decision by using 2696 Japanese respondents' data from a questionnaire survey entitled "Preference Parameters Study" that was conducted in four countries by the Global Centers of Excellence program at Osaka University. In the Probit and OLS regressions, other than relevant personal attributes being identified, the hyperbolic discounter dummy and its interaction terms with respondents' health behaviors were also included as independent variables. The results suggest that some socio-demographic variables such as gender, age, income, household size, occupational status, educational level are significant. In addition, hyperbolic discounters are found to be more likely than non-hyperbolic discounters to seek health checkups, which indicates that the effect of time preference on health checkup behavior differs significantly among the different types of time discount structures.

Time preference, outcome expectancy, and self-management in patients with type 2 diabetes

BACKGROUND

Patient self-management is crucial to prevent complications and mortality in type 2 diabetes. From an economic perspective, time preference predicts short-sighted decision making and thus might help to explain non-adherence to self-anagement recommendations. However, recent studies on this association have shown mixed results.

PURPOSE

In this study, we tested whether the combination of time preference and outcome expectancy can improve the predictions of self-management behavior.

PATIENTS AND METHODS

Data from 665 patients with type 2 diabetes were obtained from the cross-sectional KORA (Cooperative Health Research in the Region of Augsburg) GEFU 4 study. Time preference and outcome expectancy were measured by one question each, which were answered on a 4-point Likert scale. Their association with six self-managing behaviors was tested in logistic and linear regression analyses. Likewise, we examined the association between self-management and the interaction of outcome expectancy and time preference.

RESULTS

A high time preference was associated with a significantly lower sum of self-management behaviors (β=-0.29, 95% CI [-0.54, -0.04]). Higher outcome expectancy was associated with a higher self-management score (β=0.21, 95% CI [-0.03, 0.45]). The interaction model showed that low time preference was only associated with better self-management when combined with a high outcome expectancy (β=0.05, 95% CI [-0.28, 0.39] vs β=0.27, 95% CI [-0.09, 0.63]).

CONCLUSION

Time preference and outcome expectancy are interrelated predictors of patient self-management and could be used to identify and to intervene on patients with a potentially poor self-management.

Using Digital Health Technologies to Understand the Association Between Movement Behaviors and Interstitial Glucose: Exploratory Analysis

BACKGROUND

Acute reductions in postprandial glucose excursions because of movement behaviors have been demonstrated in experimental studies but less so in free-living settings.

OBJECTIVE

The objective of this study was to explore the nature of the acute stimulus-response model between accelerometer-assessed physical activity, sedentary time, and glucose variability over 13 days in nondiabetic adults.

METHODS

This study measured physical activity, sedentary time, and interstitial glucose continuously over 13 days in 29 participants (mean age in years: 44.9 [SD 9.1]; female: 59%, 17/29; white: 90%, 26/29; mean body mass index: 25.3 [SD 4.1]) as part of the Sensing Interstitial Glucose to Nudge Active Lifestyles (SIGNAL) research program. Daily minutes spent sedentary, in light activity, and moderate to vigorous physical activity were associated with daily mean glucose, SD of glucose, and mean amplitude of glycemic excursions (MAGE) using generalized estimating equations.

RESULTS

After adjustment for covariates, sedentary time in minutes was positively associated with a higher daily mean glucose (mmol/L; beta=0.0007; 95% CI 0.00030-0.00103; P<.001), SD of glucose (mmol/L; beta=0.0006; 95% CI 0.00037-0.00081; P<.001), and MAGE (mmol/L; beta=0.002; 95% CI 0.00131-0.00273; P<.001) for those of a lower fitness. Additionally, light activity was inversely associated with mean glucose (mmol/L; beta=-0.0004; 95% CI -0.00078 to -0.00006; P=.02), SD of glucose (mmol/L; beta=-0.0006; 95% CI -0.00085 to -0.00039; P<.001), and MAGE (mmol/L; beta=-0.002; 95% CI -0.00285 to -0.00146; P<.001) for those of a lower fitness. Moderate to vigorous physical activity was only inversely associated with mean glucose (mmol/L; beta=-0.002; 95% CI -0.00250 to -0.00058; P=.002).

CONCLUSIONS

Evidence of an acute stimulus-response model was observed between sedentary time, physical activity, and glucose variability in low fitness individuals, with sedentary time and light activity conferring the most consistent changes in glucose variability. Further work is required to investigate the coupling of movement behaviors and glucose responses in larger samples and whether providing these rich data sources as feedback could induce lifestyle behavior change.

A finite and stable exponential growth-adjusted indirect cost of cancer associated with discounted years of life lost in Saudi Arabia

BACKGROUND

The risk of getting cancer before full life expectancy and mortalities per year are on the rise in Saudi Arabia. Yet, evidence of economic burden of cancer in the country remains largely unknown. In order to provide evidence, we attempted to estimate the economic burden in terms of indirect cost associated with premature cancer deaths among the active or potentially economically active population aged 15-60 years in Saudi Arabia.

METHOD

Within the framework of the World Health Organization guide of identifying the economic consequences of disease and injury, our method employs cost-of-illness approach. This approach is based on a macroeconomic model that estimates the indirect cost of cancer in terms of total non-health gross domestic product resource loss associated with a disease. We used epidemiological, health system, and macroeconomic data for our estimation. We discounted the net loss at 3% and computed an extension of the loss with a finite and stable upper limit proxied by non-health gross domestic product per capita. We carried out separate analyses for male and female. We conducted sensitivity analyses to account for uncertainties of epidemiological and economic factors on the robustness of the estimated economic burden. We varied the proportion of total cancer deaths, discount rate, and value of health expenditure per capita by ±20%. We further determined which of these factors or parameters had the greatest uncertainty or variation on the net present value total non-health gross domestic product resource loss per Capita.

RESULTS

Our results indicate the indirect cost associated with cancer deaths among Saudi population aged 15-60 years to be Int$ 2.57 billion of which Int$ 1.46 billion (57%) was accounted for by females. The total indirect loss of cancer deaths increased by 8% to Int$ 2.77 billion when the loss is allowed to grow with a finite and stable upper limit proxied by non-health gross domestic product per capita over the discounted years of life lost per a death among female and male respectively. Much of the uncertainty in the determination of the value of the loss was accounted for by the proportion of total cancer deaths and discount rate, while health expenditure per capita was responsible for the least variability.

CONCLUSION

Our findings reveal evidence of indirect cost associated with cancer premature deaths in Saudi Arabia. In order to develop cancer control actions, the results of this study can inform health system policymakers not only of the extent of the enormous economic burden but also drawing attention to epidemiological and economic factors that explain the variability of the burden.

Attending to Timely Contingencies: Promoting Physical Activity Uptake Among Adults with Serious Mental Illness with an Exercise-For-Mood vs. an Exercise-For-Fitness Prescription

Despite evidence for both physical and mental health benefits achieved through regular exercise, most Americans fail to meet minimum recommendations. Altering the behavioral contingency from a focus on long-term health benefits to immediate mood benefits represents a novel method for exercise promotion. The current study examined a single-session exercise-for-mood intervention against two time-matched comparison conditions in 152 patients with serious mental illness attending a partial hospital program, a population marked by significant health disparities. This intervention was compared to a standard exercise-for-fitness intervention and a time-matched no-exercise control. Among patients with high levels of exercise prior to the partial hospital program, the exercise-for-mood intervention yielded significant increases in exercise. Implications for exercise promotion interventions among psychiatrically ill patients are discussed.

Which preferences associate with school performance?-Lessons from an exploratory study with university students

Success in life is determined to a large extent by school performance so it is important to understand the effect of the factors that influence it. In this exploratory study, in addition to cognitive abilities, we attempt to link measures of preferences with outcomes of school performance. We measured in an incentivized way risk, time, social and competitive preferences and cognitive abilities of university students to look for associations between these measures and two important academic outcome measures: exam results and GPA. We find consistently that cognitive abilities (proxied by the Cognitive Reflection Test) are very well correlated with school performance. Regarding non-cognitive skills, we report suggestive evidence for many of our measured preferences. We used two alternative measures of time preference: patience and present bias. Present bias explains exam grades better, while patience explains GPA relatively better. Both measures of time preferences have a non-linear relation to school performance. Competitiveness matters, as students, who opt for a more competitive payment scheme in our experimental task have a higher average GPA. We observe also that risk-averse students perform a little better than more risk-tolerant students. That makes sense in case of multiple choice exams, because more risk-tolerant students may want to try to pass the exam less prepared, as the possibility of passing an exam just by chance is not zero. Finally, we have also detected that cooperative preferences-the amount of money offered in a public good game-associates strongly with GPA in a non-linear way. Students who offered around half of their possible amounts had significantly higher GPAs than those, who offered none or all their money.

Discounting health and money: New evidence using a more robust method

This study compares discounting for money and health in a field study. We applied the direct method, which measures discounting independent of utility, in a representative French sample, interviewed at home by professional interviewers. We found more discounting for money than for health. The median discount rates (6.5% for money and 2.2% for health) were close to market interest rates, suggesting that at the aggregate level the direct method solves the puzzle of unrealistically high discount rates typically observed in applied economics. Constant discounting fitted the data better than the hyperbolic discounting models that we considered. The substantial individual heterogeneity in discounting was correlated with age and occupation.

Temporal Discounting and Marketing Variables: Effects of Product Prices and Brand Informational Reinforcement

By integrating the temporal discounting perspective, according to which the value of rewards is progressively discounted as a function of delay, and the Behavioral Perspective Model (BPM), according to which the purchase of products can produce utilitarian (directly obtained from use) and informational (social, mediated by others) reinforcing and punitive consequences, the present research investigated: 1) if temporal discounting would be better described by an exponential or a hyperbolic function; 2) if differently priced products would differ with respect to temporal discounting rates; and 3) if brands offering different levels of informational reinforcement would differ with respect to temporal discounting rates. In a first phase of the research, 73 undergraduate students evaluated brands of cell phone, tablet and TV set, in order to rank each brand according to the informational reinforcement level they offered. In a second phase, during an online purchasing simulation of these products, 51 students were asked to state how much they were willing to pay in order to anticipate product delivery, which was free after 21 days. Results indicated that the hyperbolic function fitted the data significantly better than the exponential function for two of the products, that products with higher prices showed lower temporal discounting rates than products with lower prices, and that brands associated with higher informational reinforcement showed higher temporal discounting rates. These findings suggest that there are complex interactive patterns of temporal discounting within- and between-products and that temporal discounting framework has great potential to inform research in consumer behavior and marketing.

Differences in decision-making as a function of drug of choice

Poor decision-making is a central feature of all substance use disorders (SUD), but substances vary in the legal and health consequences associated with their use. For example, while the negative health consequences associated with cigarette smoking are often years away, the consequences of heroin abuse can be fatal in mere hours. It remains unclear if users of these substances show decision-making patterns that differ with the relative riskiness of their drug of choice. To address this question, we reviewed studies that compared decision-making of individuals using different substances. We focused on studies assessing two of the most commonly investigated decision-making processes-delay discounting and risk taking-and specifically focused on decision-making that involved selection between options for hypothetical monetary rewards. For delay discounting, we reviewed studies that assessed decisions regarding delayed or immediate monetary rewards, and for risk-taking we reviewed studies using the Iowa Gambling Task. Studies directly comparing different SUD groups were limited in number and tended to compare alcohol or cocaine users to other substance users. Overall, these studies do not support the hypothesis that decision-making differed by drug of choice. Major limitations in the literature include failing to account for comorbid substance use and a lack of prospective longitudinal studies. Due to these limitations, conclusions should be considered provisional. Nonetheless, current findings suggest that these two facets of decision-making are similar across drugs of abuse.

Using Temporal Self-Regulation Theory to understand healthy and unhealthy eating intentions and behaviour

OBJECTIVES

The present research investigated whether Temporal Self-Regulation Theory (TST) can be used to help understand healthy and unhealthy eating intentions and behaviour.

DESIGN

A prospective design with two waves of data collection one week apart.

METHOD

An online survey measured the key components of TST (i.e., connectedness, timing and valence beliefs, intentions, past behaviour, habit strength, perceived environmental cues, and self-control) with respect to eating fruit and vegetables (F&V; N = 133) or unhealthy snacks (N = 125). Eating behaviour was assessed one week later.

RESULTS

The components of TST explained significant amounts of the variance in intentions and behaviour for intake of F&Vs (22% and 64%, respectively) and unhealthy snacks (18% and 35%, respectively). Beliefs about positive and negative short-term outcomes significantly predicted intentions to perform both behaviours. Intentions and past behaviour significantly predicted consumption of F&Vs, and past behaviour moderated the relationship between intention and behaviour which became stronger as past behaviour increased. Past behaviour and habit strength significantly predicted unhealthy snacking.

CONCLUSIONS

The findings suggest that TST may be a useful framework for understanding eating intentions and behaviour. However, research did not find support for all of the hypothesised relationships (e.g., self-regulatory capacity did not significantly predict eating behaviour and also failed to moderate the relationships between intentions and behaviour). Research using alternative measures of self-regulatory capacity, along with experimental manipulations of TST variables, may be needed to further understand eating intentions and behaviour.

Temporal preference in individuals reporting chronic pain: discounting of delayed pain-related and monetary outcomes

Opioid therapy for pain is associated with an increased risk for substance use disorders. This study's purpose was to determine the association between opioid misuse propensity (Screener and Opioid Assessment for Patients in Pain-Revised) and delay discounting (DD), a behavioral process linked to substance use disorders, which quantifies the extent to which outcomes are devalued because of their delay. Participants reporting chronic pain (N = 249) answered pain and opioid use questions and then completed 4 DD tasks. Each of these tasks assessed either money or pain consequences, framed as either rewards or punishments. Each task involved hypothetical choices between immediate smaller vs delayed larger consequences. The extant Monetary Choice Questionnaire assessed DD of money rewards, and a modified version assessed discounting of money losses (immediate smaller loss vs larger delayed loss). Based on the Monetary Choice Questionnaire, the novel Pain Relief Choice Questionnaire assessed choices between an immediate short duration of pain relief vs a longer duration of pain relief. Similarly, the novel Additional Pain Choice Questionnaire assessed choices between an immediate short duration of additional pain vs a longer duration of additional pain. Discounting of both additional pain and money losses were significantly associated with high Screener and Opioid Assessment for Patients in Pain-Revised scores-indicating participants at greatest risk for opioid misuse discount future punishments rather than future rewards compared with those at low risk. Measures of DD may have promise in more accurately identifying individuals at highest risk for opioid misuse during chronic opioid therapy.

Investigating the Impact of Cognitive Load and Motivation on Response Control in Relation to Delay Discounting in Children with ADHD

Attention-deficit/hyperactivity disorder (ADHD) is characterized by deficits in impulse control across a range of behaviors, from simple actions to those involving complex decision-making (e.g., preference for smaller-sooner versus larger later rewards). This study investigated whether changes in motor response control with increased cognitive load and motivational contingencies are associated with decision-making in the form of delay discounting among 8-12 year old children with and without ADHD. Children with ADHD (n = 26; 8 girls) and typically developing controls (n = 40; 11 girls) completed a standard go/no-go (GNG) task, a GNG task with motivational contingencies, a GNG task with increased cognitive load, and two measures of delay discounting: a real-time task in which the delays and immediately consumable rewards are experienced in real-time, and a classic task involving choices about money at longer delays. Children with ADHD, particularly girls, exhibited greater delay discounting than controls during the real-time discounting task, whereas diagnostic groups did not significantly differ on the classic discounting task. The effect of cognitive load on response control was uniquely associated with greater discounting on the real-time task for children with ADHD, but not for control children. The effect of motivational contingencies on response control was not significantly associated with delay discounting for either diagnostic group. The findings from this study help to inform our understanding of the factors that influence deficient self-control in ADHD, suggesting that impairments in cognitive control may contribute to greater delay discounting in ADHD.

To Vaccinate or to Procrastinate? That is the Prevention Question

Invoking Yaari's dual theory, we develop a model of individual vaccination decisions that incorporates quasi-hyperbolic discounting, risk aversion, and information. We test the resulting hypotheses for the flu season 2010/2011 using a representative German data set. We find a significant impact of time preferences on immunization decisions. The impact of the discount factor is significantly negative for exponential discounters. While present-biased individuals' demand for vaccination is not statistically different from the one of exponential discounters, future-biased individuals have a significantly higher probability to vaccinate. Stratification by gender reveals that these effects are entirely driven by men. That is, time preferences have no explanatory power for the vaccination decisions of women. This also applies to risk aversion, where more risk aversion implies a significantly higher probability to vaccinate for men but not women. All information measures turn out significant. Well-informed individuals have a much higher propensity to vaccinate than poorly informed individuals. If policy makers aim at improving immunization rates, then our results suggest that public policy should concentrate on providing easily accessible and concise information on the flu and the flu shot. Our results on time preferences and risk preferences imply a rather inactive role for public policy. Copyright © 2015 John Wiley & Sons, Ltd.

Doctor-patient differences in risk and time preferences: A field experiment

We conduct a framed field experiment among patients and doctors to test whether the two groups have similar risk and time preferences. We elicit risk and time preferences using multiple price list tests and their adaptations to the healthcare context. Risk and time preferences are compared in terms of switching points in the tests and the structurally estimated behavioural parameters. We find that doctors and patients significantly differ in their time preferences: doctors discount future outcomes less heavily than patients. We find no evidence that doctors and patients systematically differ in their risk preferences in the healthcare domain.

A Computer Adaptive Measure of Delay Discounting

Delay discounting has been linked to important behavioral, health, and social outcomes, including academic achievement, social functioning and substance use, but thoroughly measuring delay discounting is tedious and time consuming. We develop and consistently validate an efficient and psychometrically sound computer adaptive measure of discounting. First, we develop a binary search-type algorithm to measure discounting using a large international data set of 4,190 participants. Using six independent samples ( N = 1,550), we then present evidence of concurrent validity with two standard measures of discounting and a measure of discounting real rewards, convergent validity with addictive behavior, impulsivity, personality, survival probability; and divergent validity with time perspective, life satisfaction, age and gender. The new measure is considerably shorter than standard questionnaires, includes a range of time delays, can be applied to multiple reward magnitudes, shows excellent concurrent, convergent, divergent, and discriminant validity-by showing more sensitivity to effects of smoking behavior on discounting.

The temporal window of valuation is constricted among adolescent smokers

Healthy decisions are associated with valuation of the future whereas unhealthy decisions are associated with devaluation of the future. Comparisons of future discounting of delayed rewards in adolescent smokers and non-smokers have been equivocal and past discounting of monetary gains has not been reported in adolescents. Here, adolescents completed future and past delay discounting tasks. A mixed-model analysis of covariance using a model with the lowest Bayesian Information Criterion revealed that adolescents discount the past more than the future and smokers discount more than non-smokers. These results suggest that adolescent smokers have a constricted temporal window, which may lead to disadvantageous decisions.

Delay discounting of gains and losses, glycemic control and therapeutic adherence in type 2 diabetes

OBJECTIVE

Delay discounting is the tendency to prefer smaller, sooner rewards to larger, later ones. Poor adherence in type 2 diabetes could be partially explained by a discounted value of health, as a function of delay. Delay discounting can be described with a hyperbolic model characterized by a coefficient, k. The higher k, the less future consequences are taken into account when making decisions. This study aimed to determine whether k would be correlated with glycated hemoglobin and adherence in type 2 diabetes.

METHODS

Ninety-three patients were recruited in two diabetology departments. Delay discounting coefficients were measured with a computerized task. HbA1c was recorded and adherence was assessed by questionnaires. Potential socio-demographic and clinical confounding factors were collected.

RESULTS

There was a positive correlation between delay discounting of gains and HbA1c (r=0.242, P=0.023). This association remained significant after adjusting for potential confounding factors (F=4.807, P=0.031, η²=0.058). This association was partially mediated by adherence to medication (β=0.048, 95% CI [0.004-0.131]).

CONCLUSIONS

Glycemic control is associated with delay discounting in patients suffering from type 2 diabetes. Should these findings be replicated with a prospective design, they could lead to new strategies to improve glycemic control among these patients.

Effects of Consideration of Future Consequences and Temporal Framing on Acceptance of the HPV Vaccine Among Young Adults

This study examines how individual difference in consideration of future consequences (CFC) and temporal framing (i.e., present- vs. future-oriented message) interact to influence the persuasive outcomes of a health message promoting human papillomavirus (HPV) vaccination among young adults. Results of an experiment (N = 416) showed a significant interaction effect of CFC and temporal framing on persuasion. The nature of the interaction suggested that individuals with high CFC generally were more persuaded by the present-oriented messages, compared to the future-oriented messages. On the other hand, those with low CFC responded similarly to the present- and future-oriented messages. Implications of the findings for HPV vaccination messaging are discussed.

The absence of numbers to express the amount may affect delay discounting with humans

Human delay discounting is usually studied with experimental protocols that use symbols to express delay and amount. In order to further understand discounting, we evaluated whether the absence of numbers to represent reward amounts affects discount rate in general, and whether the magnitude effect is generalized to nonsymbolic situations in particular. In Experiment 1, human participants were exposed to a delay-discounting task in which rewards were presented using dots to represent monetary rewards (nonsymbolic); under this condition the magnitude effect did not occur. Nevertheless, the magnitude effect was observed when equivalent reward amounts were presented using numbers (symbolic). Moreover, in estimation tasks, magnitude increments produced underestimation of large amounts. In Experiment 2, participants were exposed only to the nonsymbolic discounting task and were required to estimate reward amounts in each trial. Consistent with Experiment 1, the absence of numbers representing reward amounts produced similar discount rates of small and large rewards. These results suggest that value of nonsymbolic rewards is a nonlinear function of amount and that value attribution depends on perceived difference between the immediate and the delayed nonsymbolic rewards.

Using Publicly Available Data to Construct a Transparent Measure of Health Care Value: A Method and Initial Results

POLICY POINTS

Using publicly available Hospital Compare and Medicare data, we found a substantial range of hospital-level performance on quality, expenditure, and value measures for 4 common reasons for admission. Hospitals' ability to consistently deliver high-quality, low-cost care varied across the different reasons for admission. With the exception of coronary artery bypass grafting, hospitals that provided the highest-value care had more beds and a larger average daily census than those providing the lowest-value care. Transparent data like those we present can empower patients to compare hospital performance, make better-informed treatment decisions, and decide where to obtain care for particular health care problems.

CONTEXT

In the United States, the transition from volume to value dominates discussions of health care reform. While shared decision making might help patients determine whether to get care, transparency in procedure- and hospital-specific value measures would help them determine where to get care.

METHODS

Using Hospital Compare and Medicare expenditure data, we constructed a hospital-level measure of value from a numerator composed of quality-of-care measures (satisfaction, use of timely and effective care, and avoidance of harms) and a denominator composed of risk-adjusted 30-day episode-of-care expenditures for acute myocardial infarction (1,900 hospitals), coronary artery bypass grafting (884 hospitals), colectomy (1,252 hospitals), and hip replacement surgery (1,243 hospitals).

FINDINGS

We found substantial variation in aggregate measures of quality, cost, and value at the hospital level. Value calculation provided additional richness when compared to assessment based on quality or cost alone: about 50% of hospitals in an extreme quality- (and about 65% more in an extreme cost-) quintile were in the same extreme value quintile. With the exception of coronary artery bypass grafting, higher-value hospitals were larger and had a higher average daily census than lower-value hospitals, but were no more likely to be accredited by the Joint Commission or to have a residency program accredited by the American Council of Graduate Medical Education.

CONCLUSIONS

While future efforts to compose value measures will certainly be modified and expanded to examine other reasons for admission, the construct that we present could allow patients to transparently compare procedure- and hospital-specific quality, spending, and value and empower them to decide where to obtain care.

What are the health costs of uranium mining? A case study of miners in Grants, New Mexico

BACKGROUND

Uranium mining is associated with lung cancer and other health problems among miners. Health impacts are related with miner exposure to radon gas progeny.

OBJECTIVES

This study estimates the health costs of excess lung cancer mortality among uranium miners in the largest uranium-producing district in the USA, centered in Grants, New Mexico.

METHODS

Lung cancer mortality rates on miners were used to estimate excess mortality and years of life lost (YLL) among the miner population in Grants from 1955 to 2005. A cost analysis was performed to estimate direct (medical) and indirect (premature mortality) health costs.

RESULTS

Total health costs ranged from $2·2 million to $7·7 million per excess death. This amounts to between $22·4 million and $165·8 million in annual health costs over the 1955-1990 mining period. Annual exposure-related lung cancer mortality was estimated at 2185·4 miners per 100 000, with a range of 1419·8-2974·3 per 100 000.

CONCLUSIONS

Given renewed interest in uranium worldwide, results suggest a re-evaluation of radon exposure standards and inclusion of miner long-term health into mining planning decisions.

The subjective value of probabilistic outcomes: Impact of reward magnitude on choice with uncertain rewards in rats

Interest is rising for animal modelling of Gambling disorder (GD), which is rapidly emerging as a mental health concern. In the present study, we assessed gambling proneness in male Wistar-Han rats using the "Probabilistic Delivery Task" (PDT). This operant protocol is based on choice between either certain, small amounts of food (SS) or larger amounts of food (LLL) delivered (or not) depending on a given (and progressively decreasing) probability. Here, we manipulated the ratio between large and small reward size to assess the impact of different magnitudes on rats' performance. Specifically, we drew a comparison between threefold (2 vs 6 pellets) and fivefold (1 vs 5 pellets) sizes. As a consequence, the "indifferent point" (IP, at which either choice is mathematically equivalent in terms of total foraging) was at 33% and 20% probability of delivery, respectively. Animals tested with the sharper contrast (i.e. fivefold ratio) exhibited sustained preference for LLL far beyond the IP, despite high uncertainty and low payoff, which rendered LLL a sub-optimal option. By contrast, animals facing a slighter contrast (i.e. threefold ratio) were increasingly disturbed by progressive rarefaction of rewards, as expressed by enhanced inadequate nose-poking: this was in accordance with their prompt shift in preference to SS, already shown around the IP. In conclusion, a five-folded LLL-to-SS ratio was not only more attractive, but also less frustrating than a three-folded one. Thus, a profile of gambling proneness in the PDT is more effectively induced by marked contrast between alternative options.

Increased Delay Discounting on a Novel Real-Time Task among Girls, but not Boys, with ADHD

The aim of this study was to examine delay discounting in girls and boys with ADHD-Combined type (ADHD-C) relative to typically developing (TD) children on two tasks that differ in the extent to which the rewards and delays were experienced by participants. Children ages 8-12 years with ADHD-C (n=65; 19 girls) and TD controls (n=55; 15 girls) completed two delay discounting tasks involving a series of choices between smaller, immediate and larger, delayed rewards. The classic delay discounting task involved choices about money at delays of 1-90 days and only some of the outcomes were actually experienced by the participants. The novel real-time discounting task involved choices about an immediately consumable reward (playing a preferred game) at delays of 25-100 s, all of which were actually experienced by participants. Participants also provided subjective ratings of how much they liked playing the game and waiting to play. Girls with ADHD-C displayed greater delay discounting compared to boys with ADHD-C and TD girls and boys on the real-time discounting task. Diagnostic group differences were not evident on the classic discounting task. In addition, children with ADHD-C reported wanting to play the game more and liking waiting to play the game less than TD children. This novel demonstration of greater delay discounting among girls with ADHD-C on a discounting task in which the rewards are immediately consumable and the delays are experienced in real-time informs our understanding of sex differences and motivational processes in children with ADHD. (JINS, 2016, 22, 12-23).

Thinking about Death Reduces Delay Discounting

The current study tested competing predictions regarding the effect of mortality salience on delay discounting. One prediction, based on evolutionary considerations, was that reminders of death increase the value of the present. Another prediction, based in part on construal level theory, was that reminders of death increase the value of the future. One-hundred eighteen participants thought about personal mortality or a control topic and then completed an inter-temporal choice task pitting the chance to gain $50 now against increasingly attractive rewards three months later. Consistent with the hypothesis inspired by construal theory, participants in the mortality salience condition traded $50 now for $66.67 in three months, whereas participants in the dental pain salience condition required $72.84 in three months in lieu of $50 now. Thus, participants in the mortality salience condition discounted future monetary gains less than other participants, suggesting that thoughts of death may increase the subjective value of the future.

Temporal discounting rates and their relation to exercise behavior in older adults

As our nation's population ages, the rates of chronic illness and disability are expected to increase significantly. Despite the knowledge that exercise may prevent chronic disease and promote health among older adults, many still are inactive. Factors related to exercise behaviors have been explored in recent years. However, temporal discounting is a motivational concept that has not been explored in regard to exercise in older adults. Temporal discounting is a decision making process by which an individual chooses a smaller more immediate reward over a larger delayed reward. The aim of this study was to determine if temporal discounting rates vary between exercising and non-exercising older adults.

DESIGN

This study used cross-sectional survey of 137 older adults living in the community. Older adults were recruited from 11 rural Arkansas churches. The Kirby delay-discounting Monetary Choice Questionnaire was used to collect discounting rates and then bivariate analysis was performed to compare temporal discounting rate between the exercisers and non-exercisers. Finally, multivariate analysis was used to compare discounting rate controlling for other covariates.

RESULTS

The results indicated that exercising older adults display lower temporal discounting rates than non-exercising older adults. After controlling for education, exercisers still have lower temporal discounting rates than non-exercisers (p<0.001).

CONCLUSIONS AND IMPLICATIONS

These findings are important as several chronic health conditions relate to lack of exercise especially in older adults. This research suggests that if we can find appropriate incentives for discounting individuals, some type of immediate reward, then potentially we can design programs to engage and retain older adults in exercise.

Comparing time and risk preferences across three post-industrial UK cities

Time and risk preferences are known to vary considerably across individuals but less is known about the determinants of these individual differences. This paper examines whether preferences vary by geographical location. The motivation for examining geographic heterogeneity is the higher level of mortality experienced in Glasgow over and above that explained by deprivation, sometimes referred to as the 'Glasgow effect'. Data were collected from 3702 individuals across Glasgow, Manchester and Liverpool between July and November 2011. The results show evidence of geographic preference heterogeneity. Contrary to our hypothesis, individuals in Glasgow have a lower rather than higher time preference rate. Individuals in Glasgow are on average more risk seeking compared to Liverpool and more likely to be at the tail end of the distribution (very risk seeking) compared to Manchester. Differences in risk preferences may help explain some of the differences in mortality associated with risky health behaviours such as drug and alcohol use. However, individuals in Glasgow were also more future oriented suggesting that they are less likely to engage in risky healthy behaviours. As the differences in time and risk preferences work in opposite directions in terms of health investments it less likely that these differences can help explain excess mortality in Glasgow.

Preferences for Analgesic Treatments Are Influenced by Probability of the Occurrence of Adverse Effects and the Time to Reach Maximal Therapeutic Effects

Research on shared medical decision-making suggested that both the potency of a treatment and the probability of it being successful influence individual treatment preferences. Patients also need to consider the negative attributes of treatments, such as the occurrence of adverse effects or a slow start to the therapeutic effects. It remains unclear how these attributes influence individual treatment preferences. We investigated how the analgesic effect, the adverse effect, and the time-course effect influenced the preference of analgesic treatments. Forty-five healthy volunteers participated in three hypothetical analgesic decision-making tasks. They were instructed to imagine that they were experiencing pain and choose between two hypothetical analgesic treatments: the more potent radical treatment and the less potent conservative treatment. The potency of a treatment was countered by the following attributes: the probability of working successfully, the probability of inducing an adverse effect, and the time required for the treatment to reach its maximal effect. We found that (a) when the overall probability that a treatment would induce an adverse effect decreased, the participants changed their preference from a conservative treatment to a radical treatment; (b) when the time-course for a treatment to reach its maximal effect was shortened, the participants changed their preference from a conservative treatment to a radical treatment, and (c) individual differences in prior clinical pain and the degree of imagined pain relief were associated with preferences. The findings showed that the adverse effects and the time course of treatments guide the analgesic treatment preferences, highlighting the importance of sharing information about negative attributes of treatments in pain management. The findings imply that patients may over-emphasize the occurrence of adverse effect or a slow time-course of treatment effect. In terms of shared medical decision-making, clinicians should clarify these negative attributes related to treatment to patients.

When Does the Future Begin? Time Metrics Matter, Connecting Present and Future Selves

People assume they should attend to the present; their future self can handle the future. This seemingly plausible rule of thumb can lead people astray, in part because some future events require current action. In order for the future to energize and motivate current action, it must feel imminent. To create this sense of imminence, we manipulated time metric—the units (e.g., days, years) in which time is considered. People interpret accessible time metrics in two ways: If preparation for the future is under way (Studies 1 and 2), people interpret metrics as implying when a future event will occur. If preparation is not under way (Studies 3–5), they interpret metrics as implying when preparation should start (e.g., planning to start saving 4 times sooner for a retirement in 10,950 days instead of 30 years). Time metrics mattered not because they changed how distal or important future events felt (Study 6), but because they changed how connected and congruent their current and future selves felt (Study 7).

Is there time discounting for risk premium?

Individuals with a higher subjective discount rate concentrate more on the present and delay is more significant for them. However, when a risky asset is delayed, not only is the outcome delayed but also the risk. In this paper, we suggest a new, two-stage experimental method with real monetary incentives that allows us to distinguish between the effect of the risk and the effect of the time when pricing a risky asset. We show that when individuals have greater preference for the present, their risk aversion for a risky asset realized in the future decreases. We argue that the effect of the risk for future asset is lower for individuals with higher time preference because they discount not only the outcome but also the risks.

Can't wait to lose weight? Characterizing temporal discounting parameters for weight-loss

Obesity is often related to steeper temporal discounting, that is, higher decision impulsivity for immediate rewards over delayed rewards. However, previous studies have measured temporal discounting parameters through monetary rewards. The aim of this study was to develop a temporal discounting measure based on weight-loss rewards, which may help to understand decision-making mechanisms more closely related to body weight regulation. After having their heights and weights measured, healthy young adults completed the Monetary Choice Questionnaire (MCQ), and an adapted version of the MCQ, with weight-loss as a reward. Participants also completed self-reports that measure obesity-related cognitive variables. For 42 participants who expressed a desire to lose weight, weight-loss rewards were discounted over time and had a positive correlation with temporal discounting for monetary rewards. Higher temporal discounting for weight loss rewards (i.e., preference for immediate weight loss) showed correlations with beliefs that obesity is under obese persons' control and largely due to lack of willpower, while temporal discounting parameters for monetary rewards did not. Taken together, our weight loss temporal discounting measure demonstrated both convergent and divergent validity, which can be utilized for future obesity research and interventions.

Healthy, wealthy, and wise: retirement planning predicts employee health improvements

Are poor physical and financial health driven by the same underlying psychological factors? We found that the decision to contribute to a 401(k) retirement plan predicted whether an individual acted to correct poor physical-health indicators revealed during an employer-sponsored health examination. Using this examination as a quasi-exogenous shock to employees' personal-health knowledge, we examined which employees were more likely to improve their health, controlling for differences in initial health, demographics, job type, and income. We found that existing retirement-contribution patterns and future health improvements were highly correlated. Employees who saved for the future by contributing to a 401(k) showed improvements in their abnormal blood-test results and health behaviors approximately 27% more often than noncontributors did. These findings are consistent with an underlying individual time-discounting trait that is both difficult to change and domain interdependent, and that predicts long-term individual behaviors in multiple dimensions.

Deriving time discounting correction factors for TTO tariffs

The Time Trade-off (TTO) method is a popular method for valuing health state utilities and is frequently used in economic evaluations. However, this method produces utilities that are distorted by several biases. One important bias entails the failure to incorporate time discounting. This paper aims to measure time discounting for health outcomes in a sample representative for the general population. In particular, we estimate TTO scores alongside time discounting in order to derive a set of correction factors that can be employed to correct raw TTO scores for the downward bias caused by time discounting. We find substantial positive correction factors, which are increasing with the severity of the health state. Furthermore, higher discounting is found when using more severe health states in the discounting elicitation task. More research is needed to further develop discount rate elicitation procedures and test their validity, especially in general public samples. Moreover, future research should investigate the correction of TTO values for other biases as well, such as loss aversion, and to develop a criterion to test the external validity of TTO scores.