A growing body of research demonstrates that paranoia is common in the general population. Four studies are presented that investigate factors associated with paranoia and naturalistic change in non-clinical groups. First, two experimental studies examine paranoia in the context of the Prisoner's Dilemma Game (PDG), an interpersonal research paradigm, where two players have the choice to cooperate or compete with each other. The dominant and rational choice for both players is to compete, however each players' individual reward would be greater if they both played cooperatively. Study 1 found that higher state paranoia was associated with the choice to compete. However the competitive choice can be selected due to distrust of the other player, or in order to maximise personal gain. The second experimental study employs a Three-Choice version of the PDG (PDG-Alt) that includes the option to withdraw, the rational choice when distrust of the other player is high. Higher state paranoia was associated with the withdrawal choice. These studies conclude that the withdrawal choice in the PDG –Alt provides a potential behavioral marker of state paranoia. Second, two studies examine naturalistic change in nonclinical paranoia. Idiosyncratic accounts of a single past paranoid experience are elicited and variations in dimensions known to be important in clinical paranoia are examined. Results show that levels of preoccupation, distress, impact on well being and conviction that harm was intentional significantly reduce over time. However the amount of time passed since the experience occurred is not significantly associated with level of change. Finally, in Study 4 a qualitative investigation is presented that identifies themes associated with change in nonclinical experiences of paranoia. The thesis concludes with a discussion of the theoretical, clinical and research implications of the findings.

Chan, Chun Him = 論競爭環境中出現的協作現象 / 陳俊謙. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 139-141). / Abstracts in English and Chinese. / Chan, Chun Him = Lun jing zheng huan jing zhong chu xian de xie zuo xian xiang / Chen Junqian. / Title / Abstract --- p.i / Acknowledgements --- p.v / Table of Contents --- p.vii / Chapter 1 --- Prologue --- p.1 / Chapter 2 --- Prisoners' Dilemma and Snowdrift Game --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.2 --- Formulation --- p.7 / Chapter 2.3 --- The Prisoners，Dilemma (PD) --- p.8 / Chapter 2.4 --- The Snowdrift Game (SG) --- p.9 / Chapter 2.5 --- Parameterizing Payoffs in PD --- p.10 / Chapter 2.5.1 --- The Temptation Reward Punishment Sucker System (TRPS system) --- p.10 / Chapter 2.5.2 --- "Our Expanded 2-parameter System (r, s system)" --- p.10 / Chapter 2.5.3 --- Our 1-parameter System (r system) --- p.11 / Chapter 2.5.4 --- The Benefit and Cost System (BC system) --- p.11 / Chapter 2.6 --- Parameterizing Payoffs in SG --- p.12 / Chapter 2.6.1 --- A Common 1-parameter System (rh system) --- p.13 / Chapter 2.6.2 --- Our 1-parameter System (r system) --- p.13 / Chapter 3 --- Iterated Prisoners' Dilemma (IPD) --- p.15 / Chapter 3.1 --- Tragedy of One-shot PD Game --- p.15 / Chapter 3.2 --- The First Cooperation --- p.16 / Chapter 3.2.1 --- Repeated PD Game --- p.16 / Chapter 3.2.2 --- Axelrod´ةs Tournament and Strategy “Tit-for-Tat´ح (TFT) --- p.17 / Chapter 3.3 --- The Second Cooperation --- p.18 / Chapter 3.3.1 --- Nowak and Sigmund Evolutionary Experiment --- p.18 / Chapter 3.3.2 --- Stochastic Reactive Strategies (SRSs) and Evolutionary Infinite IPD --- p.19 / Chapter 3.3.3 --- Experimental Setup --- p.20 / Chapter 3.3.4 --- Experimental Results --- p.21 / Chapter 3.3.5 --- Conclusion: TFT as a Pivot for Cooperation --- p.22 / Chapter 4 --- Evolutionary IPD with Strategy Lattices --- p.23 / Chapter 4.1 --- Sensitivity to Initial Conditions and Numerical Accuracy in IPD --- p.24 / Chapter 4.2 --- Modifications and Justifications --- p.24 / Chapter 4.3 --- Simulation Results --- p.26 / Chapter 4.3.1 --- Strategy Frequencies Xi(t) versus Time --- p.27 / Chapter 4.3.2 --- "Mean Final State in the Whole r, s Space" --- p.32 / Chapter 4.3.3 --- Time Evolution of (p) and (q) --- p.38 / Chapter 4.3.4 --- Mean Final State of a Strategy Lattice with Inclined Frequencies --- p.42 / Chapter 4.3.5 --- Conclusion --- p.50 / Chapter 5 --- Egoistic Exploiters Induced Global Generosity in Evolutionary IPD --- p.52 / Chapter 5.1 --- Introduction --- p.52 / Chapter 5.2 --- Modifications and Justifications --- p.52 / Chapter 5.3 --- "The Three Initial Conditions: Cases TO, T1 and T2" --- p.53 / Chapter 5.4 --- Simulation Results --- p.54 / Chapter 5.4.1 --- Distribution of the Final Dominant Strategies --- p.54 / Chapter 5.4.2 --- Case TO (100 Random Strategies) --- p.56 / Chapter 5.4.3 --- Case T1 (99 Random Strategies and a TFT-like Strategy) --- p.58 / Chapter 5.4.4 --- Case T2 (98 Random Strategies and both a TFT-like and an AllD-like Strategies) --- p.58 / Chapter 5.4.5 --- Comparing the Three Cases --- p.61 / Chapter 5.4.6 --- Discussion --- p.64 / Chapter 5.5 --- Analytic Manipulations for Small r Region --- p.65 / Chapter 5.5.1 --- Values of (pmps) and (qmps) for Case T2 --- p.65 / Chapter 5.5.2 --- Values of {pmps) and {qmps) for Case TO and T1 --- p.68 / Chapter 5.6 --- Conclusion --- p.71 / Chapter 6 --- The Basics of Networks --- p.72 / Chapter 6.1 --- Fully-connected Networks and Well-mixed Networks --- p.72 / Chapter 6.2 --- Simple Hypercubic Lattices --- p.73 / Chapter 6.3 --- Barabasi-Albert (BA) Scale-free Growing Networks --- p.74 / Chapter 7 --- Proposing the N-person Snowdrift Game (NSG) --- p.76 / Chapter 7.1 --- Introduction --- p.76 / Chapter 7.2 --- Limitations of 2-person Games on Networks --- p.76 / Chapter 7.3 --- The Existing N-person Games --- p.77 / Chapter 7.3.1 --- The Public Good Game (PGG) --- p.78 / Chapter 7.3.2 --- The N-person Battle of Sexes Games (NBOS) --- p.78 / Chapter 7.4 --- The NSG Scenario and Payoffs --- p.79 / Chapter 7.5 --- Everyday Examples of NSG --- p.80 / Chapter 7.6 --- Preview of Studies in Evolutionary NSG --- p.82 / Chapter 8 --- Evolutionary NSG in Well-mixed Populations --- p.84 / Chapter 8.1 --- The Method of Replicator Dynamics --- p.84 / Chapter 8.2 --- The Simulation Algorithm --- p.90 / Chapter 8.3 --- The Simulated Equilibrium Contributor Fraction x*(r) --- p.91 / Chapter 8.4 --- Analytic Manipulations on the Algorithm --- p.92 / Chapter 8.4.1 --- Conversion Probabilities and Equilibrium Conditions --- p.92 / Chapter 8.4.2 --- Discussions --- p.94 / Chapter 8.5 --- Analytic Treatments on the Time Evolution of the Contribution Level x(t) --- p.96 / Chapter 8.5.1 --- Discrete Time Equation --- p.97 / Chapter 8.5.2 --- Continuous Approximations --- p.97 / Chapter 8.5.3 --- Analytical Solutions of N=2 and N=S --- p.98 / Chapter 8.6 --- Conclusion --- p.100 / Chapter 9 --- Evolutionary NSG in Simple Hypercubic Lattices --- p.101 / Chapter 9.1 --- Comparison between Well-mixed and Lattice Populations --- p.101 / Chapter 9.2 --- Simulation Parameters --- p.103 / Chapter 9.3 --- Simulation Results for ID Lattices --- p.103 / Chapter 9.4 --- Analytic Theory for ID Lattices by Analyzing on the Local Configurations --- p.105 / Chapter 9.4.1 --- The Absence of Connected Contributors --- p.105 / Chapter 9.4.2 --- Theory for ID k=2 Chain Lattice --- p.106 / Chapter 9.4.3 --- Theory for ID k=4 Chain Lattice --- p.109 / Chapter 9.5 --- Simulation Results for 2D Lattices --- p.112 / Chapter 9.6 --- Analytic Theory for 2D k=4 Square Lattice --- p.115 / Chapter 9.7 --- Simulation Results for 3D Cubic Lattice --- p.120 / Chapter 9.8 --- Conjectures for Approximate Solutions in High-Dimensional Hy- percubic Lattices --- p.120 / Chapter 9.9 --- Extracting the Relation Neff=2k+1 --- p.122 / Chapter 9.10 --- Conclusion --- p.123 / Chapter A --- Evolutionary NSG in Barabasi-Albert Networks --- p.125 / Chapter A.l --- The New Elements in BA Networks --- p.126 / Chapter A.2 --- The Two Implementations - Model A and Model B --- p.126 / Chapter A.3 --- Results in Model A (Varying-N) --- p.127 / Chapter A.4 --- Results in Model B (Fixed-N) --- p.133 / Chapter A.5 --- Conclusion --- p.135 / Chapter B --- Supplementary Equations for Chapter 9 --- p.136 / Chapter B.l --- Equations for ID k=4 Lattice --- p.136 / Chapter B.2 --- Equations for 2D k=4 Lattice --- p.137 / Bibliography --- p.139

No description available.

No description available.

Thesis (M.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 90-92). Also available in electronic format on the Internet.

We present a simple argument which proves a general version of the scaling phenomenon recently observed in donor-recipient games by Tanimoto [Tanimoto, J., 2009. A simple scaling of the effectiveness of supporting mutual cooperation in donor-recipient games by various reciprocity mechanisms. BioSystems 96, 29-34].

Previous research on college students has found that cooperation in iterated prisoner's dilemma game is correlated with preference for delayed rewards in studies of temporal discounting. The present study attempted to replicate this finding in a drug-dependent population. Thirty-one individuals who intranasally abuse prescription opioids participated in temporal discounting and iterated prisoner's dilemma game procedures during intake for a treatment study. Rate of temporal discounting was determined for each participant at two hypothetical reward magnitudes, as well as proportion of cooperation in a 60-trial iterated prisoner's dilemma game versus a tit-for-tat strategy. Cooperation in the prisoner's dilemma game and temporal discounting rates were significantly correlated in the predicted direction: individuals who preferred delayed rewards in the temporal discounting task were more likely to cooperate in the prisoner's dilemma game.

Individuals with social anxiety have been shown to have higher levels of friendship impairment and greater difficulty establishing close relationships than persons without social anxiety. However, the mechanisms associated with such impairment have not been widely examined. Previous research suggests that deficiencies in prosocial behaviors (e.g., low warmth, limited self-disclosure, and constrained cooperation) during interpersonal exchanges may partially explain their difficulties developing close relationships. The present study aimed to examine the effect that rejection may have on prosocial behaviors, as well as other factors associated with developing and maintaining friendships, including trust, perceived likeability, closeness/connectedness, using an iterated, computerized version of the Prisoner’s Dilemma (PD) game. Participants with high (n = 56) and low (n = 35) social anxiety were asked to play the PD game with another participant (actually an experimental confederate) whom they met at the start of the study. Participants were led to believe that they were playing the PD game against the other participant but were actually playing against a computer that was programmed with a strategy meant to initially facilitate cooperation. Cooperation, or giving, in the PD game was measured primarily by the number of tokens that the participant shared with his/her partner. Additionally, participants were randomized to either rejection or non-rejection conditions. Partway through the study, those in the rejection condition were exposed to a programmed decrease in giving by their partner as well as an ambiguous in-person rejection (administered by the experimenter). Participants in the non-rejection condition were not exposed to either the programmed or in-person manipulations. Outcomes of interest included total giving during the PD game, constriction of giving, and the use of particular strategies following rejection in the PD game, as well as various measures of relationship quality collected at the end of each round of play. It was hypothesized that individuals with high social anxiety in the rejection condition would exhibit less total giving and a constricted response to low partner giving and also be less likely to use prosocial strategies to encourage cooperation (i.e., a coaxing strategy) following rejection by the partner compared to those with low social anxiety in the rejection condition. Additionally, we anticipated that those with high social anxiety in the rejection condition would provide lower ratings of the following relationship quality domains following the rejection condition: trust, closeness/connectedness, and perceived likeability than those with low social anxiety in the rejection condition. Overall, results provided little support for these hypotheses. However, there were several significant main effects that highlighted differences among those with high and low social anxiety. For example, individuals with high social anxiety had greater ratings of the expectancy of future rejection and of the importance of their next turn for maintaining the quality of their relationship with their partner. Additionally, there was a trend level (p = .08) social anxiety group by rejection condition interaction on the participant’s trust of his/her partner, such that those with high social anxiety exhibited reductions in relationship trust following rejection whereas those with low social anxiety did not. Implications of these findings as well as limitations and future directions of study are also explored. / Psychology

Previous research has identified linear boundaries within a normalized unit square for specific paired strategies within the iterated prisoner's dilemma schema. In this work, general methods of capturing linear boundaries are developed and demonstrated on a wider variety of paired strategies. The method is also tested using an alternate scoring method. An application of Burnside's Lemma simplifies the number of neighbourhood configurations to be considered. In addition, Shannon entropy is used as a means of evaluating diversity of agents evolved with different payoff matrices, by which one might locate a game that is as balanced as possible.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: There are many examples of cooperation in action in society and in nature. In some cases cooperation leads to the increase of the overall welfare of those involved, and in other cases cooperation may be to the detriment of the larger society. The presence of cooperation seems natural if there is a direct bene t to individuals who choose to cooperate. However, in examples of cooperation this bene t is not always immediately obvious. The so called prisoner's dilemma is often used as an analogy to study cooperation and tease out the factors that lead to cooperation. In classical game theory, each player is assumed to be rational and hence typically seeks to select his strategy in such a way as to maximise his own expected pay-o . In the case of the classical prisoner's dilemma, this causes both players to defect. In evolutionary game theory, on the other hand, it is assumed that players have limited knowledge of the game and only bounded rationality. Games in evolutionary game theory are repeated in rounds and players are a orded the opportunity to adapt and learn as this repetition occurs. Past studies have revealed that cooperation may be a viable strategy if the prisoner's dilemma is placed in an evolutionary context, where the evolutionary tness of a strategy is directly related to the pay-o achieved by the player adopting the strategy. One of the mechanisms that promote the persistence of cooperation in the evolutionary prisoner's dilemma is structured interaction between players. A mathematical framework for representing the evolutionary prisoner's dilemma (ESPD) is developed in this thesis. The mathematical framework is used to undertake an analytical approach (i.e. avoiding the use of simulation) towards investigating the dynamics of the ESPD with a path, cycle, plane grid or toroidal grid as underlying graph. The objective of this investigation is to determine the likelihood of the emergence of persistent cooperation between players. The ESPD on a path or a cycle admits two fundamentally di erent parameter regions; large values of the temptation-to-defect parameter are not capable of inducing persistent cooperation, while small values of this parameter allow for the possibility of persistent cooperation. It is found that the likelihood of cooperation increases towards certainty as the order of the underlying graph increases if the underlying graph is a path or cycle. The state space of the ESPD with a plane or toroidal grid graph as underlying graph grows very quickly as a function of the graph order. The automorphism classes of game states are enumerated to determine exactly how fast the size of the state space of the game grows as a function of the order of the underlying graph. Finally, the dynamics of the ESPD is investigated for a grid graph as underlying graph (in cases where the state space is small enough) by means of constructing the corresponding state graphs of the ESPD. / AFRIKAANSE OPSOMMING: Daar is baie voorbeelde van samewerking in the gemeenskap en in die natuur. In sommige gevalle lei samewerking tot 'n toename in die algehele welvaart van die betrokkenes, terwyl samewerking in ander gevalle tot nadeel van die bre er gemeenskap mag wees. Die voorkoms van samewerking blyk natuurlik te wees indien daar 'n direkte voordeel vir die individue is wat kies om saam te werk. In voorbeelde van samewerking is s o 'n voordeel egter nie altyd voor-diehand- liggend nie. Die sogenaamde prisoniersdilemma word dikwels as voorbeeld in die studie van samewerking gebruik om die faktore wat na samewerking lei, te ontbloot. In klassieke speleteorie word daar aangeneem dat elke speler rasioneel is en dus poog om sy spelstrategie op s o 'n manier te kies dat sy eie verwagte uitbetaling gemaksimeer word. In die geval van die klassieke prisoniersdilemma veroorsaak dit dat beide spelers mekaar verraai. In evolusion^ere speleteorie, daarenteen, word daar slegs aangeneem dat elke speler oor beperkte kennis van die spel en begrensde rasionaliteit beskik. Spele in evolusion^ere speleteorie word in rondtes herhaal en spelers word die geleentheid gebied om gedurende hierdie herhalingsproses aan te pas en te leer. Vorige studies het getoon dat samewerking 'n lewensvatbare strategie is indien die prisoniersdilemma in 'n evolusion^ere konteks gespeel word, waar die evolusion^ere ksheid van 'n strategie direk afhang van die uitbetaling van 'n speler wat die strategie volg. Een van die meganismes wat volhoubare samewerking in die evolusion^ere prisoniersdilemma voortbring, is gestruktureerde interaksie tussen spelers. 'n Wiskundige raamwerk word vir die voorstelling van die evolusion^ere prisoniersdilemma in hierdie tesis ontwikkel. Hierdie wiskundige raamwerk word gebruik om 'n analitiese studie (met ander woorde sonder die gebruik van simulasie) van die dinamika van die prisoniersdilemma op 'n pad, siklus, rooster in die vlak, of rooster op die torus as onderliggende gra ek van stapel te stuur. Die doel van hierdie studie is om die waarskynlikheid vir die ontstaan van volhoubare samewerking tussen spelers te bepaal. Die prisoniersdilemma op 'n pad of siklus as onderliggende gra ek het twee fundamenteel verskillende parametergebiede tot gevolg; groot waardes van die versoeking-om-te-verraai parameter lei nie tot volhoubare samewerking nie, terwyl volhoubare samewerking wel vir klein waardes van hierdie parameter moontlik is. Daar word gevind dat die kans vir volhoubare samewerking toeneem tot sekerheid namate die orde van die onderliggende gra ek groei. Die toestandsruimte van die prisoniersdilemma met 'n rooster in die vlak of 'n rooster op die torus as onderliggende gra ek groei baie vinnig as 'n funksie van die orde van die gra ek. Die outomor smeklasse van die speltoestande word getel met die doel om te bepaal presies hoe vinnig die toestandsruimte van die spel as 'n funksie van die orde van die onderliggende gra ek groei. Die dinamika van die prisoniersdilemma met 'n rooster in die vlak of 'n rooster op die torus as onderliggende gra ek word laastens deur middel van konstruksies van die ooreenstemmende toestandsgra eke ondersoek (in gevalle waar die toestandsruimte klein genoeg is).