Probability of reciprocation in repeated prisoner's dilemma games

Both social cooperation and self‐control require reciprocation. In social cooperation situations a single person's cooperative act, if not reciprocated by others, would be unreinforced both immediately and in the long term. Similarly, a single act of self‐control (refusing a single cigarette, for example), if not followed up by other such acts, would also be unreinforced immediately and in the long term. The present experiments varied probability of reciprocation in a prisoner's dilemma‐like game that could resemble a social cooperation or a self‐control situation. Participants earned points by playing against a computer. The computer offered the participant a choice between 5 or 6 points (‘cooperation’ by the computer) or between 1 or 2 points (‘defection’ by the computer). The participant's choice of the lesser alternative (‘cooperation’) or the greater alternative (‘defection’) on the current trial led, respectively, to cooperation or defection by the computer on the next trial with a probability (probability of reciprocation, PR) which could vary. When PR was greater than 63%, consistent cooperation maximized the participant's earnings. When PR was less than 63%, defection maximized earnings. Three conditions were studied: PR signaled by spinners; PR unsignaled; PR unsignaled with participants believing that they were playing with another person, not the computer. With PR = 100% (‘tit‐for‐tat’) and PR = 50%, the modal participant maximized earnings under all three conditions. With PR = 75%, participants maximized earnings only when PR was signaled. These results indicate that differences between people's tendency to cooperate with other people (social cooperation) and their tendency to cooperate with their own future interests (self‐control) may lie in differences in subjective PR. Copyright © 2001 John Wiley & Sons, Ltd.     

Prior experience and patterning in a prisoner's dilemma game

Female college students first played a pseudo-prisoner's dilemma (PPD) game with the experimenter, who followed a fixed strategy. In the first experiment the experimenter's strategies for different groups of subjects were: (a) play tit-for-tat; (b) play randomly; (c) always cooperate; (d) always defect (‘cooperation’ and ‘defection’, defined as in an actual prisoner's dilemma game). Only the tit-for-tat group increased cooperation over trials; other groups decreased cooperation. After playing the PPD with the experimenter, subjects played an actual prisoner's dilemma (PD) game with each other. In the PD game, subjects began cooperating moderately but cooperation deteriorated regardless of what the experimenter's strategy had been in the earlier (PPD) game. In a second experiment, subjects again played a PPD game with the experimenter and then played a PD game with each other. Half played one trial at a time as in the first experiment while half played in patterns of four trials at a time. In the PD game, patterning of trials retarded the development of mutual defection regardless of previous experience. The cooperation-preserving effect of patterning of trials in this social task is compared with similar effects on individual tasks involving self-control and risk-aversion. © 1998 John Wiley & Sons, Ltd.     

Depression and resilience mediate the relationship between traumatic life events and ill physical health: results from a population study

We set out to investigate the mediating roles of depression, resilience, smoking, and alcohol use, in the relationship between potentially traumatic life events and objective and subjective, physical and mental health in a single study. A face-to-face, population-based survey was conducted in Hong Kong (N = 1147). Information on health conditions and traumatic life events was obtained, and participants completed measures of subjective physical and mental health, depression, and resilience. Smoking and drinking were not significant mediators of the relationship between life events and both objective and subjective health. Depressive symptomatology was found to mediate the relationship between life threatening illness and subjective physical health, the relationship between abuse (physical and sexual) and subjective mental health, and the relationship between the death of a parent/partner and subjective mental health. Resilience was found to mediate the relationships between multiple traumatic life events and subjective physical and mental health. Our results indicate that psychological factors rather than biological are important mediators of the relationship between life events exposure and health. Our findings provide evidence that depressive symptomatology has a mediating role only in the case of specific potentially traumatic life events and that resilience is only a critical factor in the face of exposure to multiple traumatic events, rather than single events. Our results also indicate that behavioural factors, such as smoking and drinking, are not significant mediators of the relationship between life events and health.     

Differential Influence of Social Support in Emerging Adulthood Across Sources of Support and Profiles of Interpersonal and Non-Interpersonal Potentially Traumatic Experiences

Social support is protective against the negative effects of trauma, yet how these effects vary across sources of support and patterns of trauma exposure has not been examined. High co-occurrence exists among different types of trauma across domains and ages, yielding patterns of trauma exposure that may affect social support. This study identified profiles of potentially traumatic events (PTEs) experienced by 252 college students and examined the relationships between social support and mental health across these profiles. Five profiles emerged: “Non-Interpersonal Trauma Exposure,” “Adult Intimate Partner Violence,” “Poly-trauma Exposure,” “Low Trauma Exposure,” and “Childhood Family Violence.” The link between social support and adjustment differed across profiles. Family support was valuable for promoting resilience across patterns of PTEs. Friend and romantic partner support were related to lower mental health problems. Support from family and friends is particularly valuable in the context of adult intimate partner violence and childhood family violence.     

Relationship Education for Military Couples: Recommendations for Best Practice

Military couples have a number of distinctive strengths and challenges that are likely to influence their relationship adjustment. Military couples' strengths include stable employment, financial security, and subsidized health and counseling services. At the same time, military couples often experience long periods of separation and associated difficulties with emotional disconnect, trauma symptoms, and reintegrating the family. This paper describes best practice recommendations for working with military couples, including: addressing the distinctive challenges of the military lifestyle, ensuring program delivery is seen as relevant by military couples, and providing relationship education in formats that enhance the accessibility of programs.