Elements of trust: Risk and perspective-taking

Charting the neuroscience of interpersonal trust: A bibliographic literature review

Interpersonal trust is essential for societal well-being, underpinning relationships from individuals to institutions. Neuroscience research on trust has advanced swiftly since 2001. While quantitative reviews, meta-analyses, and theoretical frameworks have effectively synthesized trust neuroscience research, bibliometric analysis remains underutilized. Our bibliometric analysis aimed to provide a comprehensive overview of trust neuroscience's current state and future directions by examining its historical development, key contributors, geographic distribution, methodological paradigms, influential works, thematic trends, and overall impact. This field has been characterized by the input of a few key contributors through international collaboration, with significant contributions from the U.S., China, the Netherlands, and Germany. Research predominantly utilizes the trust game and fMRI, with a rising focus on neural networks, general trust, and differentiating behavioral from attitudinal trust. Integrating insights from psychology, economics, and sociology, this interdisciplinary field holds promise for advancing our understanding of trust through a neurobiological lens. In conclusion, our bibliographic literature review provides valuable insights and guidance for scholars, spotlighting potential avenues for further investigation in this fast-growing field.

It takes two: examining the dynamic nature of cooperative behavior in adolescents

Cooperating with those around us is an important facet of functioning in modern-day society. Forming successful cooperative relationships requires trust, reciprocity, and other interpersonal skills that continue to develop during adolescence. This study examined the dynamic nature of how trust is formed and broken among 248 adolescents (Males = 110, M Age = 15.1 years) throughout an iterative cooperative task (i.e., the Trust Game) and the interindividual differences that alter the success of their relationships. In our study, adolescents from the same classroom were anonymously paired and played a 10-trial version of the Trust Game, which examines trust and reciprocity. We found that trust is formed in the first half of the game and decreases as the threat of defection nears in the last trial. As the game progressed, the relationship between trial number and investments on the subsequent trial was mediated by percent return (ab = -0.09, 95% CI = [-0.15, -0.02]). Importantly, this relationship was moderated by social skills (p = 0.003) and impulsivity (p = 0.001), such that increases in either were associated with decreased percent return and investments on future trials. Overall, we found that cooperation is an adaptive behavior which requires trust and reciprocity, and adolescents need to exhibit both of these behaviors to have fruitful interactions. These findings suggest that interventions to help students think about their partner's perspective and stress the longer-term nature of interactions with peers would foster successful cooperation in social situations.

Connectome-based prediction of decreased trust propensity in older adults with mild cognitive impairment: A resting-state functional magnetic resonance imaging study

Trust propensity (TP) relies more on social than economic rationality to transform the perceived probability of betrayal into positive reciprocity expectations in older adults with normal cognition. While deficits in social rationality have been observed in older adults with mild cognitive impairment (MCI), there is limited research on TP and its associated resting-state functional connectivity (RSFC) mechanisms in this population. To measure TP and related psychological functions (affect, motivation, executive cognition, and social cognition), MCI (n = 42) and normal healthy control (NHC, n = 115) groups completed a one-shot trust game and additional assessments of related psychological functions. RSFC associated with TP was analyzed using connectome-based predictive modeling (CPM) and lesion simulations. Our behavioral results showed that the MCI group trusted less (i.e., had lower TP) than the NHC group, with lower TP associated with higher sensitivity to the probability of betrayal in the MCI group. In the MCI group, only negative CPM models (RSFC negatively correlated with TP) significantly predicted TP, with a high salience network (SN) contribution. In contrast, in the NHC group, positive CPM models (RSFC positively correlated with TP) significantly predicted TP, with a high contribution from the default mode network (DMN). In addition, the total network strength of the NHC-specific positive network was lower in the MCI group than in the NHC group. Our findings demonstrated a decrease in TP in the MCI group compared to the NHC group, which is associated with deficits in social rationality (social cognition, associated with DMN) and increased sensitivity to betrayal (affect, associated with SN) in a trust dilemma. In conclusion, our study contributes to understanding MCI-related alterations in trust and their underlying neural mechanisms.

Inferences about interdependence shape cooperation

During social interactions in daily life, people possess imperfect knowledge of their interdependence (i.e., how behaviors affect each person's outcomes), and what people infer about their interdependence can shape their behaviors. We review theory and research that suggests people can infer their interdependence with others along several dimensions, including mutual dependence, power, and corresponding-versus-conflicting interests. We discuss how perceptions of interdependence affect how people cooperate and punish others' defection in everyday life. We propose that people understand their interdependence with others through knowledge of the action space, cues during social interactions (e.g., partner behaviors), and priors based on experience. Finally, we describe how learning interdependence could occur through domain-specific and domain-general mechanisms.

A hierarchy of mindreading strategies in joint action participation

This paper introduces the Hierarchical Mindreading Model (HMM), a new model of mindreading in two-person, mixed-motive games such as the Prisoners’ Dilemma. The HMM proposes that the strategies available to decision makers in these games can be classified on a hierarchy according to the type of mindreading involved. At Level 0 of the HMM, there is no attempt to infer the intentions of the other player from any of the context-specific information (i.e., signals, payoffs, or partner reliability). At Level 1, decision makers rely on signals to infer the other’s intention, without considering the possibility that those signals might not reflect the other’s true intention. Finally, in Level 2 strategies, decision makers infer the other player’s intended choice by integrating information contained in their signals with the apparent reliability of the other participant and/or the game’s payoffs. The implications of the HMM were tested across four studies involving 962 participants, with results consistently indicating the presence of strategies from all three levels of the HMM’s hierarchy.

Enhancing feelings of security: How institutional trust promotes interpersonal trust

Interpersonal trust is an important source of social and economic development. Over decades, researchers debated the question whether and how public institutions influence interpersonal trust, making this relationship a much-discussed issue for scientific debate. However, experimental and behavioral data and insights on this relationship and the underlying psychological processes are rare and often inconsistent. The present set of studies tests a model which proposes that institutional trust indirectly affects trust among unrelated strangers by enhancing individuals' feelings of security. Study 1 (survey on trust in a broad spectrum of state institutions), Study 2 (nationally representative data from 16 countries), and Study 3 (experimental manipulation of institutional trust) provide convergent support for this hypothesis. Also, the results show that the effect remains consistent even after controlling for individual dispositions linked to interpersonal and institutional trust (Study 1 and 3) and country level indicators of institutional performance (Study 2). Taken together, these findings inform and contribute to the debate about the relationship between institutions and interpersonal trust by showing that when institutions are trusted, they increase feelings of security, and therefore promote interpersonal trust among strangers.

Effect of Ego Depletion on Interpersonal Trust among Individuals with Substance Use Disorders

Individuals with substance use disorders (SUD) undergo treatment to recover from addiction. However, exerting self-control, which is essential for successful abstinence from drug addiction, can cause ego depletion. This study experimentally investigated the effect of ego depletion on interpersonal trust and examined possible changes in the ego depletion effect across different abstinence periods. This study employed a 2 (ego depletion: high vs. low) × 2 (partners: non-SUD vs. SUD) mixed factorial design. The participants were 273 male individuals with SUD and with periods of drug abstinence ranging from several days to 2 years, who resided in a compulsory drug rehabilitation center. The participants were first asked to complete an ego depletion task, followed by a decision-making task in a trust game, first with a non-SUD stranger, and then with a SUD stranger. Ego depletion was not related to trust in non-SUD strangers. However, ego depleted participants were more likely to trust SUD strangers than non-ego depleted participants. Moreover, this ego depletion effect fluctuated near the end of SUD treatment. This study highlights the importance to ensure follow-up outpatient care and offer social support services for individuals with SUD after compulsory SUD treatment.

The Vexing Volunteer’s Dilemma

A volunteer’s dilemma exists when a prosocial act such as volunteering leaves the volunteer better off than if no one had volunteered but worse off than if someone else had volunteered. Ideally, a person would do what others are not doing. Research has identified psychological processes and judgmental heuristics affecting the likelihood of volunteering. People volunteer inasmuch as the other person is psychologically close, they project their own choice to others, they believe that they volunteer more than others, and they ascribe moral value to volunteering. These heuristics promote volunteering and tend to create value, but they also create risks of overvolunteering. These heuristics are discussed in the context of egocentric perception and concern with reputation.

Stepwise training supports strategic second-order theory of mind in turn-taking games

People model other people’s mental states in order to understand and predict their behavior. Sometimes they model what others think about them as well: “He thinks that I intend to stop.” Such second-order theory of mind is needed to navigate some social situations, for example, to make optimal decisions in turn-taking games. Adults sometimes find this very difficult. Sometimes they make decisions that do not fit their predictions about the other player. However, the main bottleneck for decision makers is to take a second-order perspective required to make a correct opponent model. We report a methodical investigation into supporting factors that help adults do better. We presented subjects with two-player, three-turn games in which optimal decisions required second-order theory of mind (Hedden and Zhang, 2002). We applied three “scaffolds” that, theoretically, should facilitate second-order perspective-taking: 1) stepwise training, from simple one-person games to games requiring second-order theory of mind; 2) prompting subjects to predict the opponent’s next decision before making their own decision; and 3) a realistic visual task representation. The performance of subjects in the eight resulting combinations shows that stepwise training, but not the other two scaffolds, improves subjects’ second-order opponent models and thereby their own decisions.

Make It Short and Easy: Username Complexity Determines Trustworthiness Above and Beyond Objective Reputation

Can the mere name of a seller determine his trustworthiness in the eye of the consumer? In 10 studies (total N = 608) we explored username complexity and trustworthiness of eBay seller profiles. Name complexity was manipulated through variations in username pronounceability and length. These dimensions had strong, independent effects on trustworthiness, with sellers with easy-to-pronounce or short usernames being rated as more trustworthy than sellers with difficult-to-pronounce or long usernames, respectively. Both effects were repeatedly found even when objective information about seller reputation was available. We hypothesized the effect of name complexity on trustworthiness to be based on the experience of high vs. low processing fluency, with little awareness of the underlying process. Supporting this, participants could not correct for the impact of username complexity when explicitly asked to do so. Three alternative explanations based on attributions of the variations in name complexity to seller origin (ingroup vs. outgroup), username generation method (seller personal choice vs. computer algorithm) and age of the eBay profiles (10 years vs. 1 year) were tested and ruled out. Finally, we show that manipulating the ease of reading product descriptions instead of the sellers' names also impacts the trust ascribed to the sellers.

The Reputational Consequences of Generalized Trust

The present research examines the reputational consequences of generalized trust. High-trust individuals are seen as moral and sociable, but not necessarily competent. When controlling for other traits, there is a negative relationship between trust and perceived competence (Studies 1 and 2). Compared with optimism, generalized trust has stronger effects on morality and sociability (Study 2). Furthermore, people judge those who do not discriminate between trustworthy and untrustworthy groups (unconditional trustors) more negatively than those who only trust groups that are, in fact, trustworthy (conditional trustors). Unconditional trust and unconditional distrust are both viewed negatively (Study 3), even after controlling for attitudinal similarity (Study 4). Critically, both generalized trust and discriminant ability (i.e., conditional trust) have independent reputational benefits (Study 5). These studies suggest that generalized trust plays an important role in how we perceive and judge others.

Ambiguity and expectation-neglect in dilemmas of interpersonal trust

Recent research suggests that people discount or neglect expectations of reciprocity in trust dilemmas. We examine the underlying processes and boundary conditions of this effect, finding that expectations have stronger effects on trust when they are made accessible and when they are provided as objective probabilities (Study 1). Objective expectations have stronger effects when they are based on precise, rather than ambiguous, probabilities (Study 2). We also find that trust decisions differ from individual risk-taking decisions: people are more willing to trust, and expectations have stronger effects on trusting behavior (Study 2). These results show that the availability and ambiguity of expectations shape trust decisions, and that people differentially weight expectations in dilemmas of trust and individual risk-taking.

The development of social cognition in adolescence: An integrated perspective

Social cognitive processes are critical in navigating complex social interactions and are associated with a network of brain areas termed the 'social brain'. Here, we describe the development of social cognition, and the structural and functional changes in the social brain during adolescence, a period of life characterised by extensive changes in social behaviour and environments. Neuroimaging and behavioural studies have demonstrated that the social brain and social cognition undergo significant development in human adolescence. Development of social cognition and the social brain are discussed in the context of developments in other neural systems, such as those implicated in motivational-affective and cognitive control processes. Successful transition to adulthood requires the rapid refinement and integration of these processes and many adolescent-typical behaviours, such as peer influence and sensitivity to social exclusion, involve dynamic interactions between these systems. Considering these interactions, and how they vary between individuals and across development, could increase our understanding of adolescent brain and behavioural development.

From Trust in Automation to Decision Neuroscience: Applying Cognitive Neuroscience Methods to Understand and Improve Interaction Decisions Involved in Human Automation Interaction

Human automation interaction (HAI) systems have thus far failed to live up to expectations mainly because human users do not always interact with the automation appropriately. Trust in automation (TiA) has been considered a central influence on the way a human user interacts with an automation; if TiA is too high there will be overuse, if TiA is too low there will be disuse. However, even though extensive research into TiA has identified specific HAI behaviors, or trust outcomes, a unique mapping between trust states and trust outcomes has yet to be clearly identified. Interaction behaviors have been intensely studied in the domain of HAI and TiA and this has led to a reframing of the issues of problems with HAI in terms of reliance and compliance. We find the behaviorally defined terms reliance and compliance to be useful in their functionality for application in real-world situations. However, we note that once an inappropriate interaction behavior has occurred it is too late to mitigate it. We therefore take a step back and look at the interaction decision that precedes the behavior. We note that the decision neuroscience community has revealed that decisions are fairly stereotyped processes accompanied by measurable psychophysiological correlates. Two literatures were therefore reviewed. TiA literature was extensively reviewed in order to understand the relationship between TiA and trust outcomes, as well as to identify gaps in current knowledge. We note that an interaction decision precedes an interaction behavior and believe that we can leverage knowledge of the psychophysiological correlates of decisions to improve joint system performance. As we believe that understanding the interaction decision will be critical to the eventual mitigation of inappropriate interaction behavior, we reviewed the decision making literature and provide a synopsis of the state of the art understanding of the decision process from a decision neuroscience perspective. We forward hypotheses based on this understanding that could shape a research path toward the ability to mitigate interaction behavior in the real world.

Bounded Prospection in Dilemmas of Trust and Reciprocity

Knowing when to trust others is an important social skill, but recent findings suggest that humans struggle with this dilemma—trusting strangers more than they should. Although trust decisions often do not meet the standards of rationality, they appear to be boundedly rational. We present a model of heuristic trust, according to which people focus on their own potential outcomes (what may be gained or lost from trusting), but neglect the probabilities of those outcomes occurring. We examine how trustors form expectations of reciprocity, and how those expectations relate to optimal trust decisions: some previous research suggests that people underestimate the probability of reciprocity and, relative to their subjective expectations, trust strangers too much. In contrast, our heuristic model allows for fine-grained predictions of when people trust too much and when they trust too little. The accuracy of trust depends on the selection and use of available cues; errors occur when trustors neglect valid, but difficult to process, cues and overemphasize salient cues lacking validity.

Gamma-hydroxybutyrate enhances mood and prosocial behavior without affecting plasma oxytocin and testosterone

Gamma-hydroxybutyrate (GHB) is a GHB-/GABAB-receptor agonist. Reports from GHB abusers indicate euphoric, prosocial, and empathogenic effects of the drug. We measured the effects of GHB on mood, prosocial behavior, social and non-social cognition and assessed potential underlying neuroendocrine mechanisms. GHB (20mg/kg) was tested in 16 healthy males, using a randomized, placebo-controlled, cross-over design. Subjective effects on mood were assessed by visual-analogue-scales and the GHB-Specific-Questionnaire. Prosocial behavior was examined by the Charity Donation Task, the Social Value Orientation test, and the Reciprocity Task. Reaction time, memory, empathy, and theory-of-mind were also tested. Blood plasma levels of GHB, oxytocin, testosterone, progesterone, dehydroepiandrosterone (DHEA), cortisol, aldosterone, and adrenocorticotropic-hormone (ACTH) were determined. GHB showed stimulating and sedating effects, and elicited euphoria, disinhibition, and enhanced vitality. In participants with low prosociality, the drug increased donations and prosocial money distributions. In contrast, social cognitive abilities such as emotion recognition, empathy, and theory-of-mind, and basal cognitive functions were not affected. GHB increased plasma progesterone, while oxytocin and testosterone, cortisol, aldosterone, DHEA, and ACTH levels remained unaffected. GHB has mood-enhancing and prosocial effects without affecting social hormones such as oxytocin and testosterone. These data suggest a potential involvement of GHB-/GABAB-receptors and progesterone in mood and prosocial behavior.

Trust: An Integrative Review from a Person–Situation Perspective

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.

Outcomes and expectations in dilemmas of trust

Rational trust decisions depend on potential outcomes and expectations of reciprocity. In the trust game, outcomes and expectations correspond to the structural factors of risk and temptation. Two experiments investigated how risk and temptation influenced information search and final decisions in the trust game. The central finding was that trustors underemphasized temptation relative to its effects on the expected value of trust. Instead, trustors made decisions egocentrically, focusing on potential outcomes. In Experiment 1, information search data revealed that trustors often made decisions without learning about the payoffs related to temptation. Experiment 2 investigated whether trustors were able to use temptation to form accurate expectations of reciprocity. Trustors understood, but underestimated, the relationship between temptation and the probability of reciprocity. Moreover, they did not fully consider expectations in their final trust decisions. Changes in potential outcomes had larger effects on trust than comparable changes in expectations. These results suggest that levels of trust are too high when the probability of reciprocity is low and too low when that probability is high.

Social Projection as a Source of Cooperation

Social dilemmas, such as the prisoner’s dilemma, are often seen as a conflict between rational self-interest and a moral concern for the collective. Contrary to empirical fact, classic game theory says that cooperative behavior cannot occur, and theories of moral sentiment fail to explain how cooperation comes about. Social projection theory offers a fresh look. Seeing decision making as a matter of general inductive reasoning, the theory explains why cooperative behavior occurs, correctly predicts that cooperation will vary with changes in the payoff structure, and shows how a group of self-interested individuals can obtain socially desirable outcomes. Within clearly specified boundary conditions, the theory suggests ways in which social outcomes can be improved beyond current levels.