Decades of research document individual differences in prosocial behavior using controlled experiments that model social interactions in situations of interdependence. However, theoretical and empirical integration of the vast literature on the predictive validity of personality traits to account for these individual differences is missing. Here, we present a theoretical framework that identifies 4 broad situational affordances across interdependent situations (i.e., exploitation, reciprocity, temporal conflict, and dependence under uncertainty) and more specific subaffordances within certain types of interdependent situations (e.g., possibility to increase equality in outcomes) that can determine when, which, and how personality traits should be expressed in prosocial behavior. To test this framework, we meta-analyzed 770 studies reporting on 3,523 effects of 8 broad and 43 narrow personality traits on prosocial behavior in interdependent situations modeled in 6 commonly studied economic games (Dictator Game, Ultimatum Game, Trust Game, Prisoner's Dilemma, Public Goods Game, and Commons Dilemma). Overall, meta-analytic correlations ranged between -.18 ≤ ρ̂ ≤ .26, and most traits yielding a significant relation to prosocial behavior had conceptual links to the affordances provided in interdependent situations, most prominently the possibility for exploitation. Moreover, for several traits, correlations within games followed the predicted pattern derived from a theoretical analysis of affordances. On the level of traits, we found that narrow and broad traits alike can account for prosocial behavior, informing the bandwidth-fidelity problem. In sum, the meta-analysis provides a theoretical foundation that can guide future research on prosocial behavior and advance our understanding of individual differences in human prosociality. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The field of prosociality is flourishing, yet researchers disagree about how to define prosocial behavior and often neglect defining it altogether. In this review, we provide an overview about the breadth of definitions of prosocial behavior and the related concept of altruism. Common to almost all definitions is an emphasis on the promotion of welfare in agents other than the actor. However, definitions of the two concepts differ in terms of whether they emphasize intentions and motives, costs and benefits, and the societal context. In order to improve on the conceptual ambiguity surrounding the study of prosociality, we urge researchers to provide definitions, to use operationalizations that match their definitions, and to acknowledge the diversity of prosocial behavior.

Based on lexical studies, the HEXACO (honesty-humility, emotionality, extraversion, agreeableness, conscientiousness, and openness to experience) model of personality has been proposed as a model of basic personality structure that summarizes individual differences in six broad trait dimensions. Although research across various fields relies on the HEXACO model increasingly, a comprehensive investigation of the nomological net of the HEXACO dimensions is missing entirely. Thus, it remains unclear whether each HEXACO dimension accounts for individual variation across theoretically relevant outcome criteria. We close this gap through a large-scale meta-analytic investigation, testing whether each HEXACO dimension is uniquely linked to one broad and theoretically relevant outcome domain. Results from 426 individual meta-analyses, 436 independent samples, and 3,893 effect-size estimates corroborate this unique mapping. Specifically, honesty-humility maps onto the outcome domain of exploitation, emotionality onto insecurity, extraversion onto sociality, agreeableness versus anger onto obstruction, conscientiousness onto duty, and openness to experience onto exploration. Overall, the current investigation provides a comprehensive empirical test of the (breadth of) content captured by the HEXACO dimensions and allows for a broad specification of the nomological net of the HEXACO model overall.

Trust is a key aspect of various social interactions. Correspondingly, trust has been heavily studied across different scientific disciplines. However, an integration of the diverse research and literature is still missing. Addressing this issue, we review several hundred articles on interpersonal trust among strangers and integrate them into a coherent framework, explaining trust behavior among unfamiliar agents based on an interaction between situational features and distinct personality characteristics. Understanding trust as a decision under risk, we distill 3 core components of trust behavior from the extant literature: attitudes toward risky prospects (i.e., risk aversion and loss aversion), trustworthiness expectations, and betrayal sensitivity. Each of these refers to a distinct set of causal determinants, including personality characteristics (anxiety/fear, trustworthiness, and forgiveness) which can be localized in the space defined by models of basic personality structure (e.g., the Five-Factor Model and the HEXACO model of personality). In sum, the review contributes to the understanding of trust behavior by linking and integrating the findings from various fields of trust research. Additionally, it provides fruitful directions and implications for future research.

Social desirability (SD) scales have been used for decades in psychology and beyond. These scales are sought to measure individuals' tendencies to present themselves overly positive in self‐reports, thus allowing to control for SD biases. However, research increasingly questions the validity of SD scales, proposing that SD scales measure substantive trait characteristics rather than response bias. To provide a large‐scale empirical test of the validity of SD scales, we conducted a meta‐analysis ( k = 41; N = 8980) on the relation between SD scale scores and prosocial behavior in economic games (where acting in a prosocial manner is highly socially desirable). If SD scales measure what they are supposed to (namely, SD bias), they should be negatively linked to prosocial behavior; if SD scales measure socially desirable traits, they should be positively linked to prosocial behavior. Unlike both possibilities, the meta‐analytic correlation between SD scores and prosocial behavior was close to zero, suggesting that SD scales neither clearly measure bias nor substantive traits. This conclusion was also supported by moderation analyses considering differences in the implementation of games and the SD scales used. The results further question the validity of SD scales with the implication that scholars and practitioners should refrain from using them.