Dissertations / Theses on the topic 'Probability discounting'

The purpose of the current study is to apply the delay and probability discounting in the areas of parent training and probability of success of treatment. There was a total of 31 participants that completed one demographic questionnaire and two probability and delay discounting surveys either via computer or with paper and pencil. Participants had two options in the surveys: one was an immediate reward, and one with a probability delay. The first survey gave scenarios of hours of parent training, the second was a monetary probability discounting survey.

Problem and pathological gambling has become an increasing public health concern worldwide in recent years, and individuals from China and East Asian countries may be especially vulnerable. Knowledge of how individuals make choices between outcomes that are delayed or uncertain, and of potential differences in decision making across cultures, may contribute to our understanding of factors which increase the risk of problem gambling. Our research is based on a discounting perspective in which the value of a delayed or uncertain reward decreases according to the time until or the odds against its receipt, respectively. We use experimental procedures in which individuals make a series of hypothetical choices so as to estimate an indifference point – an amount of money available immediately or with certainty – that is equal in subjective value to a delayed or uncertain reward. Our starting point is the hypothesis that reward contrast – in which the subjective value of a reward varies inversely with amount of a prior reward – plays a role in choice between delayed or probabilistic outcomes and might contribute to problem gambling. This thesis describes four experiments which investigate these ideas. Experiments 1 and 2 establish that reward contrast is a reliable phenomenon in choice. Indifference points for an intermediate reward ($475/$525) varied as predicted if its subjective value was larger when the individual had previously been making choices with a smaller amount ($50) and smaller when previously making choices with a larger amount ($5,000). Reward contrast was obtained for both delayed and probabilistic choice, using between-subjects (Experiment 1) and within-subjects (Experiment 2) designs. Experiment 3 used a computerized Card Playing Game (CPG) as an analogue gambling task and also measured delay discounting using the same task as Experiment 2. Participants began with an initial stake and could win or lose 10% of the stake with each card that they played. The critical aspect of the procedure was that the probability of winning for each card decreased as more cards were played. Participants played the CPG four times with stakes of $50, $500, $5,000 and $500 (order of $50 and $5,000 was counterbalanced). Results showed that performance on the CPG improved over successive trials, suggesting that participants learned the contingencies in the task. Although this confounded our attempt to measure reward contrast within-subjects, participants who had a $50 stake in the first deck performed better in the second deck with a $500 stake than those who had a $5,000 stake in the first deck, consistent with reward contrast. Results from the delay discounting task were correlated with CPG performance, showing that participants who had lower reward contrast and discounting rates, and greater magnitude effects won more money on the CPG task. Experiment 4 used a larger sample (N = 182) with both Chinese and Caucasian (New Zealand European) participants and recruited individuals with gambling histories, and compared performance on delay and probability discounting tasks and the CPG. Results showed that Chinese participants had higher delay discounting rates and lower probability discounting rates when data were analyzed according to the area under the discounting curve (AUC). Gamblers (those participants with scores on the South Oaks Gambling Screen [SOGS; Lesieur & Blume, 1987] > 1) were less risk averse in probability discounting and had reduced magnitude effects in delay discounting and performed more poorly on the CPG. Closer analysis of the probability discounting data showed that compared with Caucasians, Chinese were more risk averse for high probabilities of reward outcome, and less risk averse for low probabilities. Although results do not suggest that individual differences in reward contrast, as measured using our within-subjects delay discounting task, play a significant role in the maintenance of gambling behavior, the cross-cultural differences in delay and probability discounting in Experiment 4 suggest some factors that might contribute to gambling. In the General Discussion, we propose an account of the probability discounting results in terms of a tendency toward dialectical thinking and emotions in Chinese culture. Based on this result and previous research, we propose a framework for the cross-cultural analysis of risky decision making, and consider some of its broader implications for both research in decision making and issues of globalization.

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.

The present study examines delay, probability, and social discounting with money in relations to self-reported values. The participants completed a values questionnaire including questions regarding God, sex, and politics, and were divided into a low values and a high values group with the low values group n=10 and high values group = 10 for a total n=20. These groups were compared in the delay, probability, and social discounting tasks. Results indicate little to no difference in discounting between groups with an AUC for the low values group (.47), (.322), (.196), respectively and the AUC for the high values group at (.494), (.411), (.288) respectively. Individual scores for area under the curve (AUC) were tested for degree of correlation to each values question. Results indicate moderate correlations between temporal discounting and 5 sex value questions. Moderate correlations between probability discounting and political and sex value questions were observed. Finally, correlations between social discounting and politics, religious, and sex values were observed. Keywords: delay discounting, probability discounting, social discounting, politics, sex, religion

The study examined how individuals make decisions on hypothetical sexual partners and hypothetical monetary rewards in delay and probability discounting. The participants (N-75, males=42 (M=34) and females=33(M=39)) completed an electronic survey via Qualtrics. The survey consisted of 6 tasks: 1. Multiple Stimulus without Replacement Preference Assessment that consisted of pictures of potential sex partners based on the individual’s gender preference (male, female, or both); 2. Sexual Risk Survey; 3. Monetary delay discounting task; 4. Monetary probability discounting task; 5. Delay discounting of hypothetical sexual partners; and 6. Probability discounting of hypothetical sexual partners. An analysis of area under the curve (AUC) were done for the discounting tasks. The results showed that males devalued delayed sexual partner choice rank higher rates than females (t (7.97) = 2.85, p<0.05). This was also observed in females with higher scores of the Sexual Risk Survey than the lower scorers (t (10.95) = 2.35, p<0.05). AUC reflected on the scores of the SRS and with measures of sexual risk behaviours. However, there were no significant difference in discounting monetary rewards between the genders (t (11.96) = 0.1623, p>0.05).

The present study showed the impact of discounting across multiple populations that were obese to that of matched controls. The experiment used one decreasing hypothetical temporal procedure and three probabilistic health discounting procedures in which, of 38 participants interviewed, 20 were obese. It appears that age and obesity alter the subjective values of the delayed rewards within both temporal and probabilistic paradigms. The current data showed a significant difference between populations that were obese to that of the matched controls. In addition, statistically significance was found between the two obese populations within the study. Implications of the future of delay discounting are addressed, in addition to the stigma of delay discounting within behavior analysis.

The present study aimed to evaluate (a) the extent to which different impulsivity measures would be related to each other and to a risk taking measure, (b) the extent to which impulsivity, risk taking, time perception and time perspective are related to each other, and (c) the extent to which these processes differ in Latino and White American students. Experiment I was conducted at Utah State University. One hundred and fortythree participants were exposed to the delay discounting, probability discounting and temporal bisection procedures, and answered the Barratt Impulsiveness Scale (BIS-11) and the Zimbardo Time Perspective Inventory (ZTPI). Results showed that (a) the AUC for delay discounting was related to the scores on the BIS-11 scale, (b) the AUCs for delay and probability discounting were positively and significantly correlated, (c) the mean of the temporal bisection procedure was correlated with the AUC of the delay discounting procedure, (d) the scores on the ZTPI were correlated with the impulsivity measures, and (e) the scores on the ZTPI subscales were also correlated with the risk taking measure. These results suggest that different impulsivity measures may be evaluating similar decision-making processes, that impulsivity and risk taking may be different decision- making processes, and that time perception and time perspective are related to impulsivity and risk taking. Experiment II was conducted at Washington University in St. Louis, with 18 Latinos and 16 White Americans. Results show that while Latinos were more impulsive in the delay discounting procedure, their scores did not differ from the White Americans on the BIS-11. Interestingly, Latinos and White Americans did not differ on time perception, but they did differ on time perspective: Latinos scored higher on fatalism compared to White Americans.

The present study aimed to evaluate (a) the extent to which different impulsivity measures would be related to each other and to a risk taking measure, (b) the extent to which impulsivity, risk taking, time perception and time perspective are related to each other, and (c) the extent to which these processes differ in Latino and White American students. Experiment I was conducted at Utah State University. One hundred and fortythree participants were exposed to the delay discounting, probability discounting and temporal bisection procedures, and answered the Barratt Impulsiveness Scale (BIS-11) and the Zimbardo Time Perspective Inventory (ZTPI). Results showed that (a) the AUC for delay discounting was related to the scores on the BIS-11 scale, (b) the AUCs for delay and probability discounting were positively and significantly correlated, (c) the mean of the temporal bisection procedure was correlated with the AUC of the delaydiscounting procedure, (d) the scores on the ZTPI were correlated with the impulsivity measures, and (e) the scores on the ZTPI subscales were also correlated with the risk taking measure. These results suggest that different impulsivity measures may be evaluating similar decision-making processes, that impulsivity and risk taking may be different decision- making processes, and that time perception and time perspective are related to impulsivity and risk taking. Experiment II was conducted at Washington University in St. Louis, with 18 Latinos and 16 White Americans. Results show that while Latinos were more impulsive in the delay discounting procedure, their scores did not differ from the White Americans on the BIS-11. Interestingly, Latinos and White Americans did not differ on time perception, but they did differ on time perspective: Latinos scored higher on fatalism compared to White Americans.

Personal investors must postpone gratification and manage risk. This thesis examines the effects of delay and risk on personal investment decisions. The delay discounting literature is employed in developing a new parameter �ki� which integrates an investment�s term and interest rate with the hyperbolic delay discounting model. By indicating the extent to which compound interest growth compensates for hyperbolic delay discounting, ki should strongly predict the subjective appeal of prospective investment returns. Six binary-choice experiments test this hypothesis, especially via a subsidiary hypothesis that exponential growth from compound interest will eventually compensate for delay, given a sufficient term. Analyses include a novel application of signal detection principles, which found ki a superior predictor of investment appraisals compared to the normative exponential delay discounting model. Subject to boundary conditions of term and investment amount, results support the predictive capacity of ki for gross returns, implying a hitherto unrecognised degree of predictability for investment decisions. To investigate perceptions of risk with delay, three additional experiments compared preferences among hypothetical investments with varying risk and term. Risk seeking and risk aversion were detected, consistent with individual differences in hyperbolic probability discounting rates. Excessive risk aversion proved the greater problem, encouraging unnecessarily conservative investment decisions. Unexpectedly, no evidence of delay discounted risk was found. Responses consistent with higher probability discounting of larger amounts occurred, but only for a longer rather than a shorter investment term. A survey of postgraduate finance students examined how investment past performance is interpreted. Participants evaluated annual returns from hypothetical 10-year investments that varied in their mean return, volatility, and sequence of high and low returns. Evaluations generally reflected underlying investment properties. Maladaptive appraisal tendencies included unwarranted attention to the order in which high and low returns occurred within a series. Overall for this dissertation, results suggest that delay and probability discounting theory has practical relevance for understanding personal investment decisions. The principles and methodology in this dissertation are applicable to other varieties of financial and consumer behaviour.

Personal investors must postpone gratification and manage risk. This thesis examines the effects of delay and risk on personal investment decisions. The delay discounting literature is employed in developing a new parameter �ki� which integrates an investment�s term and interest rate with the hyperbolic delay discounting model. By indicating the extent to which compound interest growth compensates for hyperbolic delay discounting, ki should strongly predict the subjective appeal of prospective investment returns. Six binary-choice experiments test this hypothesis, especially via a subsidiary hypothesis that exponential growth from compound interest will eventually compensate for delay, given a sufficient term. Analyses include a novel application of signal detection principles, which found ki a superior predictor of investment appraisals compared to the normative exponential delay discounting model. Subject to boundary conditions of term and investment amount, results support the predictive capacity of ki for gross returns, implying a hitherto unrecognised degree of predictability for investment decisions. To investigate perceptions of risk with delay, three additional experiments compared preferences among hypothetical investments with varying risk and term. Risk seeking and risk aversion were detected, consistent with individual differences in hyperbolic probability discounting rates. Excessive risk aversion proved the greater problem, encouraging unnecessarily conservative investment decisions. Unexpectedly, no evidence of delay discounted risk was found. Responses consistent with higher probability discounting of larger amounts occurred, but only for a longer rather than a shorter investment term. A survey of postgraduate finance students examined how investment past performance is interpreted. Participants evaluated annual returns from hypothetical 10-year investments that varied in their mean return, volatility, and sequence of high and low returns. Evaluations generally reflected underlying investment properties. Maladaptive appraisal tendencies included unwarranted attention to the order in which high and low returns occurred within a series. Overall for this dissertation, results suggest that delay and probability discounting theory has practical relevance for understanding personal investment decisions. The principles and methodology in this dissertation are applicable to other varieties of financial and consumer behaviour.

The present study used a discounting task to evaluate how hypothetical treatment outcomes were discounter across successively greater probability values. Two discounting questionnaires were administered to thirty parents, half of which had a child with a disability. Delayed discounting of monetary rewards was assessed in relationship with probability discounting of hypothetical treatment outcomes. The questions on the probability discounting questionnaire consisted of asking participants to choose between a guaranteed percentage of symptom elimination or descending probability to eliminate all of their child’s symptoms. For example, “Which treatment outcome would you prefer for your child? (a) guaranteed elimination of 50% of symptoms or 30% chance to eliminate all symptoms.” Results showed a difference in the levels of discounting across the two groups of participants. Parents of children with disabilities discounted hypothetical monetary rewards more steeply while discounting hypothetical treatment outcomes less steeply compared to parents of children without disabilities. Exponential delay functions provided a strong fit for the monetary delayed function.

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.

Previous research has suggested that the presence of global uncertainty in choice between delayed outcomes can reduce an individual’s sensitivity to delay. However, this “common ratio effect” has only been shown using hypothetical rewards, and the question of whether the same effect would be observed in an experience-based paradigm remains unanswered. Furthermore, human temporal discounting studies have found that larger rewards are discounted less steeply than smaller rewards, but no such effect is observed in nonhumans, and no effort has been made to reconcile these two results. To these ends, a first-person shooter video game was adapted to present participants with choices between outcomes that were both delayed and uncertain. Delayed outcomes took the form of shots from a weapon that “charged” to increase its power in the time between firings. Experiment 1 incorporated uncertainty by allowing for weapon misfires. Experiment 2 replicated Experiment 1 and also examined magnitude effects by manipulating overall reinforcement density. Participants were not given exact figures for delay or probability but instead had to learn them from experience. Participants showed sensitivity to the delay manipulation, discounting less when impatience was more disadvantageous, but neither the common ratio effect nor a magnitude effect was observed. Results are discussed in the context of experience-based decision making.

Older adults tend to use strategies that differ from those used by young adults to solve decision-making tasks. MRI experiments suggest that altered strategy use during aging can be accompanied by a change in extent of activation of a given brain region, inter-hemispheric bilateralization or added brain structures. It has been suggested that these changes reflect compensation for less effective networks to enable optimal performance. One way that communication can be influenced within and between brain networks is through oscillatory events that help structure and synchronize incoming and outgoing information. It is unknown how aging impacts local oscillatory activity within the basolateral complex of the amygdala (BLA). The present study recorded local field potentials (LFPs) and single units in old and young rats during the performance of tasks that involve discrimination learning and probabilistic decision making. Wefound task-and age-specific increases in power selectively within the beta range (15-30 Hz). The increased beta power occurred after lever presses, as old animals reached the goal location. Periods of high-power beta developed over training days in the aged rats, and was greatest in early trials of a session. beta Power was also greater after pressing for the large reward option. These data suggest that aging of BLA networks results in strengthened synchrony of beta oscillations when older animals are learning or deciding between rewards of different size. Whether this increased synchrony reflects the neural basis of a compensatory strategy change of old animals in reward-based decision-making tasks, remains to be verified.

Fatores como o tempo de espera ou o risco a ser enfrentado por uma recompensa maior têm um efeito importante e, por vezes, paradoxal no processo de tomada de decisão. O Capítulo I apresenta uma discussão teórica sobre a tomada de decisão mediada por esses dois fatores, bem como sua interligação com o conceito de impulsividade e o Transtorno de Déficit de Atenção e Hiperatividade (TDAH). O Capítulo II oferece uma aplicação desses conceitos em um modelo animal do espectro da Síndrome Alcoólica Fetal, condição que apresenta algumas características semelhantes ao TDAH. Utilizando ratos expostos ao álcool no período pré-natal, duas tarefas de tomada de decisão mediada por tempo ou probabilidade foram usadas para testar se esses animais apresentam diferenças em seus padrões de escolha. Não foram encontradas diferenças significativas entre grupos controle e experimentais. Futuros estudos com outros protocolos, espécies e/ou linhagens são desejáveis.
Factors such as the time to wait, or the risk to be faced for a bigger reward have an important and, sometimes, paradoxical effect on the decision making process. Chapter I presents a theoretical discussion about decision making mediated by these two factors, as well as how they relate to the concept of impulsivity and the Attention-Deficit Hyperactivity Disorder (ADHD). Chapter II offers a practical application of these concepts in an animal model of the spectrum of Fetal Alcohol Syndrome, a condition that presents some similar characterstics in comparison to ADHD. Using rats prenatally exposed to ethanol, two decision making tasks, mediated by time or probability, were used to test if these animals show any difference in their patterns of choice. No significant differences were found between control and experimental groups. Future studies with other protocols, species and/or strains are desirable.

This research is aimed at developing a probabilistic based model for heavy-duty pavement project evaluation. To achieve this objective studies were conducted in the area of traffic flow, traffic delay modelling, pavement deterioration, pavement condition monitoring, maintenance diaries, vehicle operating cost parameters and economic theories related to asset management. Extensive literature reviews on related topics were carried out as part of the process of developing this model. The major features of the model are its ability to assign random probabilities to various pavement maintenance options and calculate the probabilistic based whole of life cost for any pavement type, for a given design life. To accomplish the task of developing the model a simple traffic delay model was developed. Traffic delay and costs were alculated using the model for predetermined pavement and traffic conditions. Studies were conducted using this model to prove the validity of considering user costs as the predominant cost in any pavement project evaluation process. A probabilistic based whole of life costing model concept was developed along with a supporting traffic delay model and a range of spreadsheets to meet the objectives of this research. This concept was tested using a complete range of data and by making some realistic assumptions. The results obtained from this model are quite encouraging and are expected to provide the basis for a new innovative tool to pavement project engineers for the purpose of pavement project evaluation.

abstract: The value of safe sex may be discounted based on contextual factors associated with an opportunity for sex. College students (n = 75) in a within-subjects study selected hypothetical sexual partners from a set of pictures and classified them based on attractiveness and estimated chance of having an STI. In the sexual delay discounting (SDD) task, participants rated their likelihood (0 – 100%) of waiting for some period of time (e.g., 3 hours) to have protected sex with their selected partners, when they could have immediate sex without protection. In the sexual probability discounting (SPD) task, participants rated their likelihood of having protected sex if the opportunity was uncertain (e.g., 50%), when they could have unprotected sex for sure (100%). All participants included in the final analyses were aware of and had a positive attitude towards protection against STIs as they indicated preference for immediate (or certain) protected sex. Results show that participants’ willingness to have safe sex systematically decreased as the delay to and odds against having safe sex increased. However, these discounting patterns were observed only in some partner conditions but not others, showing that preference for delayed (or uncertain) safe sex was altered by perceived attractiveness and STI risk of sexual partners. Moreover, the hyperbolic discounting model provided good to acceptable fit to the delay and probability discounting data in most-wanted and least-STI conditions. Gender differences in devaluation of safe sex were also found.
Dissertation/Thesis
Masters Thesis Psychology 2016