Background: Schizophrenia is associated with deficits in decision-making. Aim: To determine the effects of smoking status on delay discounting in schizophrenia in comparison to non-psychiatric controls. Method: Cross-sectional comparison of delay discounting across smoking and psychiatric status. Hypotheses: Individuals with schizophrenia were hypothesized to have higher rates of delay discounting than controls; Non-smokers with schizophrenia would have higher rates of delay discounting than smokers. Control smokers would discount future rewards more than non-smokers. Results: No significant differences in delay discounting were observed between psychiatric groups. Smokers with schizophrenia exhibited more delay discounting than non-smokers. Within the psychiatric group, former smokers discount rates were similar to current smokers. Conclusion: Delay discounting deficits in schizophrenia and modulation by cigarette smoking were not supported; our pattern of results in schizophrenia does suggest that deficits in delay discounting in these patients appears to be a trait rather than a state-dependent phenomenon.

Background: Schizophrenia is associated with deficits in decision-making. Aim: To determine the effects of smoking status on delay discounting in schizophrenia in comparison to non-psychiatric controls. Method: Cross-sectional comparison of delay discounting across smoking and psychiatric status. Hypotheses: Individuals with schizophrenia were hypothesized to have higher rates of delay discounting than controls; Non-smokers with schizophrenia would have higher rates of delay discounting than smokers. Control smokers would discount future rewards more than non-smokers. Results: No significant differences in delay discounting were observed between psychiatric groups. Smokers with schizophrenia exhibited more delay discounting than non-smokers. Within the psychiatric group, former smokers discount rates were similar to current smokers. Conclusion: Delay discounting deficits in schizophrenia and modulation by cigarette smoking were not supported; our pattern of results in schizophrenia does suggest that deficits in delay discounting in these patients appears to be a trait rather than a state-dependent phenomenon.

This thesis explores the implications of non-human primates’ propensity to hyperbolically discount the future. Hyperbolic discounting occurs when small, near-term rewards are preferred over larger rewards that are realized at a future point in time, but these preferences do not hold when the choice between long term and short term rewards is made at a time far removed from when the choice produces rewards-- i.e., at a time when the payoff of the choice is distant. I discuss two mutually exclusive models that attempt to explain why non-human primates hyperbolically discount: the cognitivist and the behaviorist model. I then present evidence that supports the cognitivist model and undermines the behaviorist model. I then argue that a “War of Interests” (WOI) occurs within the non-human primate mind. I explain this WOI model, discuss its philosophical implications, and then conclude with a general theory of the non-human primate mind.

Preference is an important element in economic analysis, but usually regarded an inborn and exogenous characteristic. By the concept of natural selection, evolutionary game theory can explain lots of animal characteristics, including humans. With this idea, this paper extends the classical Hawk-Dove game to a two-period-life model, in which fights can cause deaths. We derive the population dynamics and the evolutiona-rily stable strategy. The competitive attitude and patience are determined by resource value and cost. And under a given common patience level, the evolutionarily stable strategy is a mixed strategy. But if the ¡§announcement effect,¡¨ an extra benefit from showing the winning record, is large enough, all-hawk may be the equilibrium. In ad-dition, under variable patient levels, the model can determine the equilibrium patience, and numerical simulation shows that dove-strategy accompanies a higher patient level than hawk.

The dissertation comprises an introductory Chapter, four papers and a summary Chapter. First, a new class of Bayesian dynamic partition models for the Nelson- Siegel family of non-linear state-space Bayesian statistical models is developed. This class is applied to studying the term structure of government yields. A sequential time series of Bayes factors, which is developed from this approach, shows that term structure could act as a leading indicator of economic activity. Second, we develop a class of non-MCMC algorithms called “Direct Sampling”. This Chapter extends the basic algorithm with applications to Generalized Method of Moments and Affine Term Structure Models. Third, financial economics is characterized by long-standing problems such as the equity premium and risk free rate puzzles. In the chapter titled “Bayesian Learning, Distributional Uncertainty and Asset-Return Puzzles” solutions for equilibrium prices under a set of subjective beliefs generated by Dirichlet Process priors are developed. It is shown that the “puzzles” could disappear if a “tail thickening” effect is induced by the representative agent. A novel Bayesian methodology for retrospective calibration of the model from historical data is developed. This approach shows how predictive functionals have important welfare implications towards long-term growth. Fourth, in “Social Discounting Using a Bayesian Nonparametric model” the problem of how to better quantify the uncertainty in long-term investments is considered from a Bayesian perspective. By incorporating distribution uncertainty, we are able to provide confidence measures that are less “pessimistic” when compared to previous studies. These measures shed a new and different light when considering important cost-benefit analysis such as the valuation of environmental policies towards the resolution of global warming. Finally, the last Chapter discusses directions for future research and concludes the dissertation. / text

Psychopharmacological studies have implicated the mesolimbic dopamine (DA) system in the mediation of cost/benefit evaluations about effort-related costs associated with larger rewards. However, the role of DA in risk-based decision making remains relatively unexplored. The present study investigated how systemic manipulations of DA transmission affect risky choice assessed with a probabilistic discounting task. Over discrete trials, rats between two levers; a press on the “small/certain” lever always delivered one reward pellet, whereas a press on the other, “large/risky” lever delivered four pellets, but the probability of receiving reward decreased across the four trial blocks (100%, 50%, 25%, 12.5%). In separate groups of well-trained rats we assessed the effects of the DA releaser amphetamine, as well as receptor selective agonists and antagonists. Amphetamine consistently increased preference for the large/risky lever; an effect that was blocked or attenuated by co-administration of either D₁ (SCH23390) or D₂ (eticlopride) receptors antagonists. Blockade of either of these receptors alone induced risk aversion. Conversely, stimulation of D₁ (SKF81297) or D₂ (bromocriptine) receptors also increased risky choice. In contrast, activation of D₃ receptors with PD128,907 induced risk aversion. Likewise, D₃ antagonism with nafadotride potentiated the amphetamine-induced increase in risky choice. Blockade or stimulation of D₄ receptors did not reliably alter patterns of choice. These findings indicate that DA plays a critical role in mediating risk-based decision making, where increased activation of D₁ and D₂ receptors biases choice towards larger, probabilistic rewards, whereas D₃ receptors appear to exert opposing effects on this form of decision making.

Psychopharmacological studies have implicated the mesolimbic dopamine (DA) system in the mediation of cost/benefit evaluations about effort-related costs associated with larger rewards. However, the role of DA in risk-based decision making remains relatively unexplored. The present study investigated how systemic manipulations of DA transmission affect risky choice assessed with a probabilistic discounting task. Over discrete trials, rats between two levers; a press on the “small/certain” lever always delivered one reward pellet, whereas a press on the other, “large/risky” lever delivered four pellets, but the probability of receiving reward decreased across the four trial blocks (100%, 50%, 25%, 12.5%). In separate groups of well-trained rats we assessed the effects of the DA releaser amphetamine, as well as receptor selective agonists and antagonists. Amphetamine consistently increased preference for the large/risky lever; an effect that was blocked or attenuated by co-administration of either D₁ (SCH23390) or D₂ (eticlopride) receptors antagonists. Blockade of either of these receptors alone induced risk aversion. Conversely, stimulation of D₁ (SKF81297) or D₂ (bromocriptine) receptors also increased risky choice. In contrast, activation of D₃ receptors with PD128,907 induced risk aversion. Likewise, D₃ antagonism with nafadotride potentiated the amphetamine-induced increase in risky choice. Blockade or stimulation of D₄ receptors did not reliably alter patterns of choice. These findings indicate that DA plays a critical role in mediating risk-based decision making, where increased activation of D₁ and D₂ receptors biases choice towards larger, probabilistic rewards, whereas D₃ receptors appear to exert opposing effects on this form of decision making.

AN ABSTRACT OF THE THESIS OF CHAD A. PONCINIE. For the Master of Science degree in Behavior Analysis and Therapy, presented on 21 June 2013. TITLE: AN EXAMINATION OF DELAY DISCOUNTING IN SEX OFFENDERS WITH DUAL DIAGNOSES MAJOR PROFESSOR: Dr. Mark R. Dixon Discounting of delayed rewards by sex offenders with dual diagnoses was compared to discounting of delayed rewards by matched control non-offenders with dual diagnoses. All participants completed a hypothetical choice task in which they made repeated choices between 10 dollars/servings after a delay and an equal or lesser amount available immediately. The delay to the large reward was varied from 1 day to 2 years across conditions. Indifference points between immediate and delayed rewards were identified at each delay condition by varying the amount of immediate money across choice trials. Overall, those identified as sex offenders discounted the delayed reward more steeply than did the control non-offenders.

The responses from a probability discounting procedure was collected to make between and within-group comparisons of the quality of sex with different sexual partners and monetary rewards between individuals who have engaged in infidelity in the past and individuals who have never engaged in infidelity in the past. A modification to the quality of the overall relationship was introduced to identify whether discounting outcomes could be altered. Gender differences were also examined. Results showed a significant difference between groups when discounting the quality of sex of differing sexual partners but no difference between groups with monetary rewards. There was also a significant difference between commodity types within the group that have never engaged in infidelity but no difference between commodity type within the group that has engaged in infidelity in the past. The modification of the quality of the overall relationship resulted in no significant difference in responses to the probability discounting trials and there were no significant gender differences.

Animal models can contribute significantly to our understanding of human gambling behavior. However, no proposed animal models of human gambling have been tested using human subjects. The purpose of the present paper was to validate an animal model of gambling with human subjects. Twenty undergraduate rehabilitation students (all women) were recruited and participated for extra course credit. Participants were presented with a concurrent choice between two different simulated slot machines; one machine with symbols and one machine without symbols. During the first 50 choice trials, the payout of the two machines was equated at 50% overall. For the remaining 50 choice trials, probability of winning on the machine with symbols was systematically decreased by 10% overall every ten trials until there was no probability of winning for the last ten trails. On average, participants showed a preference for the machine with symbols during choice trials when win rate was equated; allocating significantly more than 50% of responding to this machine. A repeated measures ANOVA indicated that response allocation to the symbol machine only significantly decreased in the final two conditions (10% and EXT) and did not decrease significantly across any other conditions. Results were also interpreted through behavioral economic analyses. Results indicate that conditioned reinforcement may affect the subjective value of probabilistic reinforcers in humans. These results are similar to those obtained with pigeons under similar conditions and may imply that animal models are relevant to the study of human gambling behavior.