Probability discounting and gambling: a meta-analysis

Effects of methamphetamine on probability discounting in rats using concurrent chains

How stimulant drugs affect risky choice and the role of reinforcement magnitude has been an important question for research on impulsivity. This study investigated rats' responding on a rapid acquisition, concurrent chains, probability discounting task under methamphetamine administration. In each block of four sessions, probability of reinforcement delivery was unequal (0.5/1.0, 1.0/0.5) or equal, (1.0/1.0, 0.5/0.5) while amount of reinforcement was constant and unequal. This allowed for an estimate of probability discounting and the magnitude effect (where larger reinforcers are discounted at a greater rate) in each block. Baseline, acute and chronic methamphetamine administration, and re-establish baseline phases were completed. Rats showed sensitivity to probability and magnitude in baseline, as well as a magnitude effect whereby preference for the larger reinforcement was greater with 100% than 50% reinforcement probability. Acute methamphetamine dose-dependently reduced the probability effect. There were no effects of chronic administration and only probability discounting was maintained in the re-establish baseline phase. This was the first procedure to find a magnitude effect with rats in a probability discounting procedure and demonstrates that acute methamphetamine reduces both the probability and magnitude effects which increases propensity for risky choice.

Distributed attribute representation in the superior parietal lobe during probabilistic decision-making

Several studies have examined the neural substrates of probabilistic decision-making, but few have systematically investigated the neural representations of the two objective attributes of probabilistic rewards, that is, the reward amount and the probability. Specifically, whether there are common or distinct neural activity patterns to represent the objective attributes and their association with the neural representation of the subjective valuation remains largely underexplored. We conducted two studies (nStudy1  = 34, nStudy2  = 41) to uncover distributed neural representations of the objective attributes and subjective value as well as their association with individual probability discounting rates. The amount and probability were independently manipulated to better capture brain signals sensitive to these two attributes and were presented simultaneously in Study 1 and successively in Study 2. Both univariate and multivariate pattern analyses showed that the brain activities in the superior parietal lobule (SPL), including the postcentral gyrus, were modulated by the amount of rewards and probability in both studies. Further, representational similarity analysis revealed a similar neural representation between these two objective attributes and between the attribute and valuation. Moreover, the SPL tracked the subjective value integrated by the hyperbolic function. Probability-related brain activations in the inferior parietal lobule were associated with the variability in individual discounting rates. These findings provide novel insights into a similar neural representation of the two attributes during probabilistic decision-making and perhaps support the common neural coding of stimulus objective properties and subjective value in the field of probabilistic discounting.

Effects of economic context and reward amount on delay and probability discounting

Steep delay and shallow probability discounting are associated with myriad problem behaviors; thus, it is important to understand factors that influence the degree of discounting. The present study evaluated the effects of economic context and reward amount on delay and probability discounting. Two hundred thirteen undergraduate psychology students completed four delay- or probability-discounting tasks. Participants were exposed to hypothetical narratives involving four bank amounts ($750, $12,000, $125,000, and $2,000,000). The delayed/probabilistic amount was $3,000 for the two smaller bank amounts and $500,000 for the two larger bank amounts. The discounting tasks included five delays to, or probabilities of, receipt of the larger amount. The area under the empirical discounting function was calculated for each participant. Participants discounted delayed and uncertain outcomes more when the bank amount was smaller than the outcome (i.e., the economic context was low). Participants discounted the delayed larger amounts less than delayed smaller amounts, even when the relative economic context was the same. In contrast, probability discounting did not differ across magnitudes, which suggests that economic context may attenuate the magnitude effect in probability discounting. The results further highlight the importance of considering the economic context in delay and probability discounting.

COVID-19-related financial scarcity is associated with greater delay discounting but not probability discounting

Prior studies suggest that scarcity increases delay discounting (devaluation of delayed outcomes) and disturbs other decision-making processes. Evidence on the effect of COVID-19 on delay discounting is mixed. Also, no study has examined the effect of COVID-19-related scarcity on probability discounting (devaluation of probabilistic outcomes). The goal of the study was to examine cross-sectional associations between financial impact during the COVID-19 pandemic, delay discounting, and probability discounting. During April 2020, 1012 participants with low income were recruited on Amazon Mechanical Turk and completed measures of delay and probability discounting, perceived COVID-19-related financial impacts, and food security. Regression analyses indicate that compared to those with no COVID-19-related financial impacts, those with severe COVID-19-related financial impacts had greater delay discounting of money and greater delay discounting of a grocery gift card. Also, greater food insecurity in the past month was associated with greater delay discounting of a grocery gift card but not delay discounting of money. Perceived COVID-19 related financial impact was not associated with probability discounting. Combined with laboratory experiments, this study provides additional support for the idea that feelings of scarcity may increase delay discounting. However, as this study was observational, no assumptions of causality should be made about the specific effect of COVID-19 on delay discounting.

Hyperbolic modeling and assessment of hypothetical health behaviors during a viral outbreak using crowdsourced samples

The COVID-19 pandemic provided an opportunity to investigate factors related to public response to public health measures, which could help better prepare implementation of similar measures for inevitable future pandemics. To understand individual and environmental factors that influence likelihood in engaging in personal and public health measures, three crowdsourced convenience samples from Amazon Mechanical Turk (MTurk) completed likelihood-discounting tasks of engaging in health behaviors given a variety of hypothetical viral outbreak scenarios. Experiment 1 assessed likelihood of mask wearing for a novel virus. Experiment 2 assessed vaccination likelihood based on efficacy and cost. Experiment 3 assessed likelihood of seeking health care based on number of symptoms and cost of treatment. Volume-based measures and three-dimensional modeling were used to analyze hypothetical decision making. Hypothetical public and personal health participation increased as viral fatality increased and generally followed a hyperbolic function. Public health participation was moderated by political orientation and trust in science, whereas treatment-seeking was only moderated by income. Analytic methods used in this cross-sectional study predicted population-level outcomes that occurred later in the pandemic and can be extended to various health behaviors.

"Distractor" effects in delay discounting of probability by pigeons

Impulsive behavior can be measured by performance on a successive delay-discounting task, in which a response to a stimulus provides a small reinforcer sooner (SS), but in the absence of a response, a larger reinforcer later (LL). Previous research suggests that the presence of a concurrent "distractor" stimulus, to which responding has no programed consequence, can result in increased LL reinforcers. In the present experiments, we used differences in the probability of reinforcement between SS and LL (rather than magnitude of reinforcement) and tested the hypothesis that the concurrent stimulus may become a Pavlovian conditioned stimulus. For the Red-Only group, a response to the SS stimulus resulted in a reinforcer with a low probability (SS), whereas the absence of a response resulted in a reinforcer with a high probability (LL). For the Red-Green group, (analogous to the more typical simultaneous choice between an SS and LL stimulus) the absence of a response to the SS stimulus replaced the SS stimulus with the LL stimulus and a response to the LL stimulus resulted in the reinforcer. Thus, for the Red-Green group, the concurrent stimulus should have been less effective because responding to the concurrent stimulus was not immediately followed by the reinforcer. In Experiment 1, the concurrent stimulus was a yellow key-light; in Experiment 2, it was a houselight. In both experiments, the concurrent stimulus was effective in increasing the number of LL reinforcers and the effect was larger for the Red-Only group than for the Red-Green group.

Beyond Systematic and Unsystematic Responding: Latent Class Mixture Models to Characterize Response Patterns in Discounting Research

Operant behavioral economic methods are increasingly used in basic research on the efficacy of reinforcers as well as in large-scale applied research (e.g., evaluation of empirical public policy). Various methods and strategies have been put forward to assist discounting researchers in conducting large-scale research and detecting irregular response patterns. Although rule-based approaches are based on well-established behavioral patterns, these methods for screening discounting data make assumptions about decision-making patterns that may not hold in all cases and across different types of choices. Without methods well-suited to the observed data, valid data could be omitted or invalid data could be included in study analyses, which subsequently affects study power, the precision of estimates, and the generality of effects. This review and demonstration explore existing approaches for characterizing discounting and presents a novel, data-driven approach based on Latent Class Analysis. This approach (Latent Class Mixed Modeling) characterizes longitudinal patterns of choice into classes, the goal of which is to classify groups of responders that differ characteristically from the overall sample of discounters. In the absence of responders whose behavior is characteristically distinct from the greater sample, modern approaches such as mixed-effects models are robust to less-systematic data series. This approach is discussed, demonstrated with a publicly available dataset, and reviewed as a potential supplement to existing methods for inspecting and screening discounting data.

The Gamblification of Investing: How a New Generation of Investors Is Being Born to Lose

Investing and gambling share key features, in that both involve risk, the coming together of two or more people, and both are voluntary activities. However, investing is generally a much better way than gambling for the average person to make long-run profits. This paper reviews evidence on two types of “gamblified” investment products where this advantage does not hold for investing: high-frequency stock trading and high-risk derivatives. This review defines a gamblified investment product as one that leads most investors to lose, that attracts people at risk of experiencing gambling-related harm, and that utilizes product design principles from gambling (either by encouraging a high frequency of use or by providing the allure of big lottery-like wins). The gamblification of investing produces novel challenges for the regulation of both financial markets and gambling.

Towards a Unifying Account of Dopamine’s Role in Cost-Benefit Decision Making

Dopamine is thought to play a crucial role in cost-benefit decision making, but so far there is no consensus on the precise role of dopamine in decision making. Here, we review the literature on dopaminergic manipulations of cost-benefit decision making in humans and evaluate how well different theoretical accounts explain the existing body of evidence. Reduced D₂ stimulation tends to increase the willingness to bear delay and risk costs (i.e., wait for later rewards, take riskier options), while increased D₁ and D₂ receptor stimulation increases willingness to bear effort costs. We argue that the empirical findings can best be explained by combining the strengths of two theoretical accounts: in cost-benefit decision making, dopamine may play a dual role both in promoting the pursuit of psychologically close options (e.g., sooner and safer rewards) and in computing which costs are acceptable for a reward at stake. Moreover, we identify several limiting factors in the study designs of previous investigations that prevented a fuller understanding of dopamine's role in value-based choice. Together, the proposed theoretical framework and the methodological suggestions for future studies may bring us closer to a unifying account of dopamine in healthy and impaired cost-benefit decision making.

The steroidogenic inhibitor finasteride reverses pramipexole-induced alterations in probability discounting

Pramipexole is a potent agonist of D₃ and D₂ dopamine receptors, currently approved for clinical use in Parkinson's disease (PD) and restless leg syndrome. Several studies have shown that pramipexole significantly increases the risk of pathological gambling and impulse-control disorders. While these iatrogenic complications can impose a severe social and financial burden, their treatment poses serious clinical challenges. Our group previously reported that the steroidogenic inhibitor finasteride reduced pathological gambling severity in PD patients who developed this complication following pramipexole treatment. To study the mechanisms underlying these effects, here we tested the impact of finasteride in a rat model of pramipexole-induced alterations of probability discounting. We previously showed that, in rats exposed to low doses of the monoamine-depleting agent reserpine (1mg/kg/day, SC), pramipexole (0.3mg/kg/day, SC) increased the propensity to engage in disadvantageous choices. This effect was paralleled by a marked D₃ receptor upregulation in the nucleus accumbens. First, we tested how finasteride (25-50mg/kg, IP) intrinsically affects probability discounting. While the highest dose of finasteride produced a marked lack of interest in lever pressing (manifested as a significant increase in omissions), the 25mg/kg (IP) dose did not intrinsically modify probability discounting. However, this finasteride regimen significantly reduced the adverse effects of reserpine and pramipexole in probability discounting by diminishing rats' propensity to engage in highly disadvantageous probabilistic choices. The same regimen also reversed the upregulation of D₃ receptors in the nucleus accumbens induced by reserpine and pramipexole. These findings confirm that finasteride opposes the impulsivity caused by pramipexole and suggest that this effect may be underpinned by a normalizing effect on D₃ receptor expression in the nucleus accumbens.

Reward-Related Decision-Making in Current and Past Disordered Gambling: Implications for Impulsive Choice and Risk Preference in the Maintenance of Gambling Disorder

Impulsive reward-related decision-making (RRDM) is robustly associated with gambling disorder (GD), although its role in the development and perpetuation of GD is still being investigated. This project sought to examine the possible roles of impulsive and risky choice, two aspects of RRDM, in the perpetuation of GD. Additionally, the potential moderating role of comorbid substance misuse was considered. A total of 434 participants with symptoms of current GD and symptoms of concurrent substance use disorder (SUD; n = 105), current GD with past SUD (n = 98), past GD with current SUD (n = 53), or past GD with past substance use disorder (SUD; n = 92), and 96 healthy controls were recruited through MTurk. Participants completed a randomly adjusting delay discounting (a measure of impulsive choice) and probabilistic discounting (a measure of risky choice) task and self-report questionnaires of gambling participation, GD and SUD symptomology, and trait impulsivity. Although control participants showed significantly greater delay discounting compared to individuals with a current or history of GD, no significant group differences emerged between individuals with current GD or a history of GD. Individuals with current GD showed significantly less probabilistic discounting compared to individuals with a history of GD and control participants showed the greatest rates of probabilistic discounting. These effects remained after controlling for lifetime gambling symptom severity and trait impulsivity. Overall, these findings suggest a potential maintaining role of risky choice in gambling disorder, but do not support a maintaining role for impulsive choice.

The sooner the better: clinical and neural correlates of impulsive choice in Tourette disorder

Reward sensitivity has been suggested as one of the central pathophysiological mechanisms in Tourette disorder. However, the subjective valuation of a reward by introduction of delay has received little attention in Tourette disorder, even though it has been suggested as a trans-diagnostic feature of numerous neuropsychiatric disorders. We aimed to assess delay discounting in Tourette disorder and to identify its brain functional correlates. We evaluated delayed discounting and its brain functional correlates in a large group of 54 Tourette disorder patients and 31 healthy controls using a data-driven approach. We identified a subgroup of 29 patients with steeper reward discounting, characterised by a higher burden of impulse-control disorders and a higher level of general impulsivity compared to patients with normal behavioural performance or to controls. Reward discounting was underpinned by resting-state activity of a network comprising the orbito-frontal, cingulate, pre-supplementary motor area, temporal and insular cortices, as well as ventral striatum and hippocampus. Within this network, (i) lower connectivity of pre-supplementary motor area with ventral striatum predicted a higher impulsivity and a steeper reward discounting and (ii) a greater connectivity of pre-supplementary motor area with anterior insular cortex predicted steeper reward discounting and more severe tics. Overall, our results highlight the heterogeneity of the delayed reward processing in Tourette disorder, with steeper reward discounting being a marker of burden in impulsivity and impulse control disorders, and the pre-supplementary motor area being a hub region for the delay discounting, impulsivity and tic severity.

Structural characteristics of fixed-odds sports betting products

BACKGROUND AND AIMS

A literature exists on the structural characteristics of electronic gambling machines (EGMs), which are design innovations that can promote spending excessive time and money on these games. Fixed-odds sports betting products, where bettors place sports bets against a bookmaker, have also seen significant innovations in recent years. Despite some differences between these gambling products, similar structural characteristics could also be relevant to sports betting. The aim was to review previous research on contemporary fixed-odds sports betting products, and to identify whether structural characteristics from the EGM literature are also relevant to sports betting.

METHODS

Structural characteristics uncovered by two influential reviews of EGMs were identified, and their relevance to fixed-odds sports betting products discussed via a narrative review.

RESULTS

Structural characteristics of payout interval and potential betting frequency (in-play betting), multiplier potential (accumulators, complex bets, multis), win probability and payout ratio (all bets), bettor involvement (custom sports betting products, cash out), skill required (all bets), and near-misses (accumulators, complex bets, multis) were all identified in modern fixed-odds sports betting products.

DISCUSSION AND CONCLUSIONS

Fixed-odds sports betting products have increasingly incorporated structural characteristics previously found in EGMs. Future research could further assess the extent to which these structural characteristics contribute to fixed-odds sports bettors spending excessive amounts of time and money while betting. These findings can help guide further sports betting research, contribute to an improved understanding of the potential universality of gambling product design, and inform policy.

The prevalence and features of schizophrenia among individuals with gambling disorder

BACKGROUND-OBJECTIVES

Few studies have analyzed the comorbid presence of gambling disorder (GD) with schizophrenia, its sociodemographic correlates and clinical implications. This study estimated the prevalence of the dual diagnosis (GD with schizophrenia) and the differences in the profiles of patients with and without the dual condition.

METHOD

The sample included n = 3,754 patients consecutively accepted for treatment for GD. Sociodemographics, gambling-related variables, psychopathological state and personality traits were assessed and compared between the groups.

RESULTS

The prevalence of schizophrenia within patients who met clinical criteria for GD was 4.4% (95% confidence interval: 3.8%-5.1%). Variables related to the dual presence of GD with schizophrenia were single marital status, lower education level, inactive working status, socioeconomic disadvantage, younger age, earlier onset of gambling problems, worse global psychopathological state and more dysfunctional personality profile (higher level in harm avoidance and lower level in cooperativeness, reward dependence, persistence and self-directedness).

CONCLUSION

The presence of schizophrenia among patients with GD was around 4 times higher than the prevalence rate estimated in the reference general population. The differences in the profiles of GD patients with and without schizophrenia suggest that individuals with the dual diagnosis condition require unique assessment considerations and tailored treatment interventions specifically designed for the clinical and functioning higher risk.

Risk-Based Decision Making: A Systematic Scoping Review of Animal Models and a Pilot Study on the Effects of Sleep Deprivation in Rats

Animals, including humans, frequently make decisions involving risk or uncertainty. Different strategies in these decisions can be advantageous depending the circumstances. Short sleep duration seems to be associated with more risky decisions in humans. Animal models for risk-based decision making can increase mechanistic understanding, but very little data is available concerning the effects of sleep. We combined primary- and meta-research to explore the relationship between sleep and risk-based decision making in animals. Our first objective was to create an overview of the available animal models for risky decision making. We performed a systematic scoping review. Our searches in Pubmed and Psychinfo retrieved 712 references, of which 235 were included. Animal models for risk-based decision making have been described for rodents, non-human primates, birds, pigs and honey-bees. We discuss task designs and model validity. Our second objective was to apply this knowledge and perform a pilot study on the effect of sleep deprivation. We trained and tested male Wistar rats on a probability discounting task; a “safe” lever always resulted in 1 reward, a “risky” lever resulted in 4 or no rewards. Rats adapted their preferences to variations in reward probabilities (p < 0.001), but 12 h of sleep deprivation during the light phase did not clearly alter risk preference (p = 0.21).

The influence of chronological age on cognitive biases and impulsivity levels in male patients with gambling disorder

BACKGROUND AND AIMS

Due to the contribution of age to the etiology of gambling disorder (GD), there is a need to assess the moderator effect of the aging process with other features that are highly related with the clinical profile. The objective of this study is to examine the role of the chronological age into the relationships between cognitive biases, impulsivity levels and gambling preference with the GD profile during adulthood.

METHODS

Sample included n = 209 patients aged 18-77 years-old recruited from a Pathological Gambling Outpatients Unit. Orthogonal contrasts explored polynomial patterns in data, and path analysis implemented through structural equation modeling assessed the underlying mechanisms between the study variables.

RESULTS

Compared to middle-age patients, younger and older age groups reported more impairing irrational beliefs (P = 0.005 for interpretative control and P = 0.043 for interpretative bias). A linear trend showed that as people get older sensation seeking (P = 0.006) and inability to stop gambling (P = 0.018) increase. Path analysis showed a direct effect between the cognitive bias and measures of gambling severity (standardized effects [SE] between 0.12 and 0.17) and a direct effect between impulsivity levels and cumulated debts due to gambling (SE = 0.22).

CONCLUSION

Screening tools and intervention plans should consider the aging process. Specific programs should be developed for younger and older age groups, since these are highly vulnerable to the consequences of gambling activities and impairment levels of impulsivity and cognitive biases.

The adverse effects of pramipexole on probability discounting are not reversed by acute D2 or D3 receptor antagonism

Pramipexole (PPX) is a D₂ and D₃ dopamine receptor agonist approved for clinical use, which is associated with a higher risk of impulse-control disorders. Using a rat model, we recently found that low doses of the monoamine-depleting agent reserpine (RES; 1 mg/kg/day, SC) dramatically increased the untoward effects of PPX (0.3 mg/kg/day, SC) on probability discounting, a key impulsivity function. To further understand the neurobehavioral mechanisms underlying these effects, we first tested whether the combination of PPX and RES may lead to a generalized enhancement in risk taking, as tested in the suspended wire-beam paradigm. The association of RES and PPX did not augment the proclivity of rats to cross the bridge in order to obtain a reward, suggesting that the effects of RES and PPX on probability discounting do not reflect a generalized increase in impulsivity. We then studied what receptors mediate the effects of PPX in RES-treated rats. The combination of RES and PPX increased membrane expression and binding of D₃, but not D₂ dopamine receptors, in the nucleus accumbens. However, the behavioral effects of PPX and RES were not reduced by acute treatments with the D₂/D₃ receptor antagonist raclopride (0.01-0.05 mg/kg, SC), the highly selective D₂ receptor antagonist L-741,626 (0.1-1 mg/kg, SC) or the D₃ receptor antagonists GR 103691 (0.1-0.3 mg/kg, SC) and SB 277011A (1-10 mg/kg, SC). These findings collectively suggest that the effects of PPX in probability discounting do not reflect generalized enhancements in impulsivity or acute dopamine D₂ or D₃ receptor activation.

Efficacy of Pharmacological Interventions in Targeting Decision-Making Impairments across Substance and Behavioral Addictions

Decision-making impairments reflect tendencies towards risky or unwise choices as manifested by presence of psychiatric symptoms or cognitive impairment (e.g. representation of value, inhibitory control-response selection, learning). Such impairments are suggested by the hallmark symptoms of substance and behavioral addictions, which include escalation over time (of substance intake or a given behavior), lack of control, neglect of other domains of life, and cognitive distortions (such as ‘chasing losses’ in gambling disorder). Amongst the putative behavioral addictions, most epidemiological data exist for gambling disorder, which is now included in DSM-5 as a substance-related and addictive disorder. However, other disorders share parallels and may also constitute behavioral addictions, such as compulsive stealing (kleptomania), compulsive shopping, and compulsive sexual behavior. The current paper presents a narrative review of evidence for cognitive decision-making impairments in addictions, as well as pharmacological treatments of these disorders that may have relevance for improving decision-making. We find that objective decision-making deficits have been widely reported in patients with substance use disorders and gambling disorder, compared to controls. Decision-making in the other behavioral addictions is under-studied. Evidence-based pharmacological treatments for some of these addictive disorders, for example, opioid antagonists and glutamatergic agents, modulate neural systems playing key roles in decision-making. But clinical trials have seldom examined effects of such treatments on objective decision-making measures. Future research directions are discussed, including the need to include standardized outcome measures of decision-making (tasks and imaging) alongside traditional clinical measures, to better understand and enhance underlying treatment mechanisms.