Loneliness is associated with more trust but worse trustworthiness expectations.

Subjective feelings of loneliness emerge due to unsatisfactory social relationships, representing a major risk for mental and physical well-being. Despite its social nature, evidence on how loneliness affects social behaviours and expectations is lacking. Using Bayesian analyses and economic games, we show in three different studies that lonelier individuals trusted their partners to a greater extent despite less favourable trustworthiness expectations, showing a greater discrepancy between their trusting behaviours and their expectations of others' trustworthiness. Such discrepancy was reversed in extravert individuals who also reported to be less lonely. These results provide evidence on two opposing effects of loneliness as a motivator for social connections and promoter of social withdrawal, and demonstrate the moderating role of personality traits. This work contributes to a better understanding of how loneliness impacts social behaviour and social expectations, with important downstream clinical implications for varying health conditions associated with heightened feelings of loneliness.

The anatomical structure of sex differences in trust propensity: A voxel-based morphometry study.

Trust is a key component of human relationships. Sex differences in trust behavior have been elucidated by parental investment theory and social role theory, attributing men's higher trust propensity to their increased engagement in physically and socially risky activities aimed at securing additional resources. Although sex differences in trust behavior exist and the neuropsychological signatures of trust are known, the underlying anatomical structure of sex differences is still unexplored. Our study aimed to investigate the anatomical structure of sex differences in trust behavior toward strangers (i.e., trust propensity, TP) by employing voxel-based morphometry (VBM) in a sample of healthy young adults. We collected behavioral data for TP as measured with participants in the role of trustors completing the one-shot trust game (TG) with anonymous partners as trustees. We conducted primary region of interest (ROI) and exploratory whole-brain (WB) VBM analyses of high-resolution structural images to test for the association between TP and regional gray matter volume (GMV) associated with sex differences. Confirming previous studies, our behavioral results demonstrated that men trusted more than women during the one-shot TG. Our WB analysis showed a greater GMV related to TP in men than women in the precuneus (PreC), whereas our ROI analysis in regions of the default-mode network (dorsomedial prefrontal cortex [dmPFC], PreC, superior temporal gyrus) to simulate the partner's trustworthiness, central-executive network (ventrolateral PFC) to implement a calculus-based trust strategy, and action-perception network (precentral gyrus) to performance cost-benefit calculations, as proposed by a neuropsychoeconomic model of trust. Our findings advance the neuropsychological understanding of sex differences in TP, which has implications for interpersonal partnerships, financial transactions, and societal engagements.

Direct reciprocity and reputation shape trust decisions similarly in blind and sighted individuals.

This study addresses the effects of blindness on trust. Using an auditory version of the multi-round Trust Game, we investigated the effect of reputation and reciprocity on trust decisions in early blind and sighted participants. During each round of the game, participants were endowed with a sum of money and had to decide how much they wanted to invest in their partners, who were manipulated as a function of their good or bad reputation and individualistic or cooperative behavior. The data showed that negative first impression about the partner (bad reputation and/or selfish behavior) impacted more blind participants than sighted ones. However, following repeated interactions with the partners, the overall mean investment aligned between the blind and sighted groups. We interpret these findings as suggesting that blindness may guide participants to a more cautionary behavior when dealing with partners with negative initial characteristics.

Exploration of the influence of the quantification method and reference scheme on feedback-related negativity and standardized measurement error of feedback-related negativity amplitudes in a trust game.

Various approaches have been taken over the years to quantify event-related potential (ERP) responses and these approaches may vary in their utility connecting empirical research and scientific claims. In this work we compared different quantification methods as well as the influence of three reference methods (linked mastoids, average reference, and current source density) on the resulting ERP amplitude. We use the experimental effects and effect sizes (Cohen's d) to evaluate the different methodological variants and we calculate intraclass correlation coefficients (ICC). In addition, the bootstrapped standard error of the means (SME, Luck et al., 2021), which was recently suggested as a quality criterion for ERP research, is used for this purpose. Our example for an ERP is the feedback-related negativity (FRN) to feedback about trustee behavior in a trust game with participants in the trustor position. We found that the quantification methods concerning the FRN influenced the absolute value of condition effects in the experimental paradigm. Yet, the patterns of effects were detected by all chosen methods, except for the 'individual difference wave'-based peak window approach. In addition, our findings stress the importance of checking the reference electrodes concerning effects of the experimental conditions. Furthermore, interactions of topographical distribution and reference choice should be considered. Finally, we were able to show that the SME is lower for more datapoints that are given in the quantification period of the FRN, and higher for more negative FRN amplitudes. These biases may lead to divergence of SME and effect size detection. Therefore, if the SME was used to compare different processing choices one should consider controlling for these important aspects of the data and possibly include other quality criteria like effect sizes.

Impaired social learning in patients with major depressive disorder revealed by a reinforcement learning model

Background/objective: Patients with major depressive disorder (MDD) have altered learning rates for rewards and losses in non-social learning paradigms. However, it is not well understood whether the ability to learn from social interactions is altered in MDD patients. Using reinforcement learning during the repeated Trust Game (rTG), we investigated how MDD patients learn to trust newly-met partners in MDD patients. Method: Sixty-eight MDD patients and fifty-four controls each played as ‘investor’ and interacted with ten different partners. We manipulated both the level of trustworthiness by varying the chance of reciprocity (10, 30, 50, 70 and 90%) and reputation disclosure, where partners’ reputation was either pre-disclosed or hidden. Results: Our reinforcement learning model revealed that MDD patients had significantly higher learning rates for losses than the controls in both the reputation disclosure and non-disclosure condition. The difference was larger when reputation was not disclosed than disclosed. We observed no difference in learning rates for gains in either condition. Conclusions: Our findings highlight that abnormal learning for losses underlies the social learning process in MDD patients. This abnormality is higher when situational unpredictability is high versus low. Our findings provide novel insights into social rehabilitation of MDD. (AU)

Impaired social learning in patients with major depressive disorder revealed by a reinforcement learning model.

Background/objective: Patients with major depressive disorder (MDD) have altered learning rates for rewards and losses in non-social learning paradigms. However, it is not well understood whether the ability to learn from social interactions is altered in MDD patients. Using reinforcement learning during the repeated Trust Game (rTG), we investigated how MDD patients learn to trust newly-met partners in MDD patients. Method: Sixty-eight MDD patients and fifty-four controls each played as 'investor' and interacted with ten different partners. We manipulated both the level of trustworthiness by varying the chance of reciprocity (10, 30, 50, 70 and 90%) and reputation disclosure, where partners' reputation was either pre-disclosed or hidden. Results: Our reinforcement learning model revealed that MDD patients had significantly higher learning rates for losses than the controls in both the reputation disclosure and non-disclosure condition. The difference was larger when reputation was not disclosed than disclosed. We observed no difference in learning rates for gains in either condition. Conclusions: Our findings highlight that abnormal learning for losses underlies the social learning process in MDD patients. This abnormality is higher when situational unpredictability is high versus low. Our findings provide novel insights into social rehabilitation of MDD.

Does rDLPFC activity alter trust? Evidence from a tDCS study.

Trust plays an important role in the human economy and people's social lives. Trust is affected by various factors and is related to many brain regions, such as the dorsolateral prefrontal cortex (DLPFC). However, few studies have focused on the impact of the DLPFC on trust through transcranial direct current stimulation (tDCS), although abundant psychology and neuroscience studies have theoretically discussed the possible link between DLPFC activity and trust. In the present study, we aimed to provide evidence of a causal relationship between the rDLPFC and trust behavior by conducting multiple rounds of the classical trust game and applying tDCS over the rDLPFC. We found that overall, anodal stimulation increased trust compared with cathodal stimulation and sham stimulation, while the results in different stages were not completely the same. Our work indicates a causal relationship between rDLPFC excitability and trust behavior and provides a new direction for future research.

Trust in virtual ingroup or outgroup members relies on perceived self-other overlap.

Why do we trust each other? We carried out three experiments to test whether interpersonal trust depends on perceived self-other overlap. As previous studies suggest that enfacing (feeling ownership for, and include more into oneself of the face of) an avatar might make one trust this avatar more, we exposed participants to faces of ingroup and outgroup avatars that moved in synchrony or out of synchrony with the participant's own facial movements, and assessed the impact of synchrony on self-other overlap and trust measures. Experiment 1 used ingroup faces and successfully showed that synchrony (manipulated within-participants) increased self-other overlap and trust, which we assessed by means of the Trust Game and the Implicit Association Test (IAT). In Experiment 2, which used outgroup faces and a within-participants design, synchrony still increased scores in the Trust Game but the IAT was no longer affected. Experiment 3 replicated Experiment 2 but with synchrony varying between participants, which eliminated the synchrony effect in both trust measures. Importantly, Inclusion of Other in the Self (IOS) ratings were found to predict the IAT effect in synchronous conditions. Taken altogether, our findings suggest that interpersonal trust is mainly driven by perceived self-other overlap. Besides group identification, appearance, and voluntary movement, synchrony is just one of several sources contributing to perceived self-other overlap.

Adolescents' trust and reciprocity toward friends, unknown peers, and community members.

Using a newly developed version of the Trust Game among 196 adolescents aged 11-20 years, this study examined whether adolescents distinguish between trust and reciprocity to unknown peers, friends, and community members. We also tested for effects of age, gender, and individual differences in attending to others' emotions, emotional support to friends, societal contributions, and institutional and interpersonal trust beliefs. Results indicated that adolescents showed the least trust and reciprocity to unknown peers, more to a community member, and most to friends. Reciprocity increased with age, and individual differences in societal contributions and interpersonal trust were positively related to trust and reciprocity. This study was the first to show that community members are a specific target in adolescents' social world.

Trust or Distrust: The Effect of Facial Emotion and Trustworthy Behavior on Trust Decision-Making.

Based on the model of emotion as social information, this study explores the effects of facial emotions and trustworthy behavior on trust decision-making in trust game through two experiments. The present study used trust game explores the impact of players' facial emotion, arousal and trustworthy behavior on individual trust decision-making through two experiments. The results can be summed up as follows: (1) in the repeated interaction with four players, individuals invest more in trustworthy players than untrustworthy players; (2) individuals invested more in trustworthy players with happy facial emotions, while untrustworthy players with angry facial emotions received less investment. High-arousal facial emotion results in a more extreme investment by the individual; (3) when the players' facial emotion and behavior are inconsistent, the individual will judge according to the player's current behavior, rather than the facial emotion or past behavior.

When Does Competence Matter? Character as a Moderator in the Development of Trust.

This article examines the relationship between the two fundamental attributes of the trustee: character and competence. Although the trust research predominantly adopts an additive perspective, our research emphasizes a moderation (i.e., multiplicative) relationship and the significance of their interaction. We find that competence is an important but not always reliable predictor of trust. First, the positive effect of competence is conditional on the trustee's high character. Second, higher competence can have a lower marginal effect as character decreases. Furthermore, situational assurance weakens the effect of character on competence, which explains the additive joint effect found in previous research. Our modified trust game also makes a methodological contribution by examining the interaction between the various personal and situational sources of trust (as compared with the lone operationalization of character in the classic trust game). We discuss the shortcomings of the additive perspective and the implications of our method and findings.

Corrigendum: Feeling ostracized by others' smartphone use: the effect of phubbing on fundamental needs, mood, and trust.

[This corrects the article DOI: 10.3389/fpsyg.2022.883901.].

Ethnic discrimination unlearned: experience in the repeated Trust Game reduces trust bias.

Introduction: Discrimination toward ethnic minorities is a persistent societal problem. One reason behind this is a bias in trust: people tend to trust their ingroup and comparatively distrust outgroups. Methods: In this study, we investigated whether and how people change their explicit trust bias with respect to ethnicity based on behavioral interactions with in- and outgroup members in a modified Trust Game. Results: Subjects' initial explicit trust bias disappeared after the game. The change was largest for ingroup members who behaved unfairly, and the reduction of trust bias generalized to a small sample of new in- and outgroup members. Reinforcement learning models showed subjects' learning was best explained by a model with only one learning rate, indicating that subjects learned from trial outcomes and partner types equally during investment. Discussion: We conclude that subjects can reduce bias through simple learning, in particular by learning that ingroup members can behave unfairly.

Trust game, survey trust, are they correlated? Evidence from China.

Trust Game and survey trust are the two most popular measurements in the field of trust research, but most studies conducted in developing countries have found low or even insignificant correlations between them, we therefore validated this phenomenon in the cultural context of the largest developing country, China. Within-country differences can be of the same magnitude as the between country differences, especially in a culturally diverse China. Thus, we focus on comparing the characteristics of trust in the South and North regions of China. Through zero-order correlation and hierarchical regression analysis, our findings are consistent with those of numerous developing countries: Trust Game is lowly correlated with in-group trust survey and not with out-group trust survey. On the other hand, we found that Chinese individuals exhibit a distinct pattern of in-group trust, and there is no fundamental difference in the characteristics of trust between the South and the North.

Mentalizing in an economic games context is associated with enhanced activation and connectivity in the left temporoparietal junction.

Prior studies in Social Neuroeconomics have consistently reported activation in social cognition regions during interactive economic games, suggesting mentalizing during economic choice. Such mentalizing occurs during active participation in the game, as well as during passive observation of others' interactions. We designed a novel version of the classic false-belief task (FBT) in which participants read vignettes about interactions between agents in the ultimatum and trust games and were subsequently asked to infer the agents' beliefs. We compared activation patterns during the economic games FBT to those during the classic FBT using conjunction analyses. We find significant overlap in the left temporoparietal junction (TPJ) and dorsal medial prefrontal cortex, as well as the temporal pole (TP) during two task phases: belief formation and belief inference. Moreover, generalized Psychophysiological Interaction (gPPI) analyses show that during belief formation, the right TPJ is a target of both the left TPJ and the right TP seed regions, whereas during belief inferences all seed regions show interconnectivity with each other. These results indicate that across different task types and phases, mentalizing is associated with activation and connectivity across central nodes of the social cognition network. Importantly, this is the case for both the novel economic games and the classic FBTs.

A study of trust behavior and its neural basis in athletes under long-term exercise training.

Previous research has suggested that long-term exercise training can influence trusting behaviors, but the supporting evidence is limited. Therefore, exploring inter-athlete trust behaviors and its neural mechanism could better answer the potential association between athletic training and trust behaviors. Accordingly, the present study used a trust game (TG) task to assess interpersonal trust behavior in the sex-specific athlete group and the ordinary college group; and a functional near-infrared spectroscopy (fNIRS) hyperscanning technology was used to capture the interpersonal neural synchronization (INS) in brain regions of interest to the dyads. The results showed that the athlete group had significantly higher trust behaviors and significantly higher INS in the left frontal pole and left dorsolateral prefrontal than the college group; male athletes had significantly higher trust behaviors and significantly higher INS in the left dorsolateral prefrontal than female athletes. This study suggests that athletes have better trusting behaviors and that this advantage may be related to enhanced INS in the left dorsolateral prefrontal lobe.

Social and non-social categorisation in investment decisions and learning.

Categorical processes allow us to make sense of the environment effortlessly by grouping stimuli sharing relevant features. Although these processes occur in both social and non-social contexts, motivational, affective, and epistemic factors specific to the social world may motivate individuation over categorisation of social compared with non-social stimuli. In one experiment, we tested this hypothesis by analysing the reliance on categorical versus individuating information when making investment decisions about social and non-social targets. In an adaptation of the iterative trust game, participants from three experimental groups had to predict the economic outcomes associated with either humans (i.e., social stimuli), artificial races (i.e., social-like stimuli), or artworks (i.e., non-social stimuli) to earn economic rewards. We observed that investment decisions with humans were initially biased by categorical information in the form of gender stereotypes, but later improved through an individuating learning approach. In contrast, decisions made with non-social stimuli were initially unbiased by categorical information, but the category-outcomes associations learned through repeated interactions were quickly used to categorise new targets. These results are discussed along with motivational and perceptual mechanisms involved in investment decisions and learning about social and non-social agents.

Connectome-based individualized prediction of reciprocity propensity and sensitivity to framing: a resting-state functional magnetic resonance imaging study.

BACKGROUND: The social representation theory states that individual differences in reciprocity decisions are composed of a stable central core (i.e., reciprocity propensity, RP) and a contextual-dependent periphery (i.e., sensitivity to the framing effect; SFE, the effect by how the decision is presented). However, the neural underpinnings that explain RP and SFE are still unknown. METHOD: Here, we employed prediction and lesion models to decode resting-state functional connectivity (RSFC) of RP and SFE for reciprocity decisions of healthy volunteers who underwent RS functional magnetic resonance imaging and completed one-shot trust (give frame) and distrust (take frame) games as trustees. RESULTS: Regarding the central core, reciprocity rates were positively associated between the give and take frame. Neuroimaging results showed that inter-network RSFC between the default-mode network (DMN; associated with mentalizing) and cingulo-opercular network (associated with cognitive control) contributed to the prediction of reciprocity under both frames. Regarding the periphery, behavioral results demonstrated a significant framing effect-people reciprocated more in the give than in the take frame. Our neuroimaging results revealed that intra-network RSFC of DMN (associated with mentalizing) contributed dominantly to the prediction of SFE. CONCLUSION: Our findings provide evidence for distinct neural mechanisms of RP and SFE in reciprocity decisions.

The "beauty premium" effect of voice attractiveness of long speech sounds in outcome-evaluation event-related potentials in a trust game.

Previous research suggested that people with attractive voices had an advantage in economic games, even if the voices were only presented for 400 ms. The present study investigated the influence of voice attractiveness on the cooperative trust behavior with longer exposure times to the voices. Event-related potentials (ERPs) were recorded during the feedback outcome evaluation. Participants heard a voice of the partner for 2,040 ms and decided whether to invest to the partner for a possibility to gain more money. The results showed that participants made more invest choices to the attractive partners, replicating the "beauty premium" effect of the attractive voices. Moreover, participants were more likely to invest to male partners. The ERP analysis for the outcome showed that the difference waves of feedback-related negativity (FRN) amplitude were smaller in the attractive voice condition than in the unattractive voice condition, suggesting that the rewarding effect of attractive voices weakened the frustrating feelings of the loss. In sum, the present study confirms that attractive voices with longer presentation durations facilitate cooperative behavior and modulate the processing of feedback evaluations.

Variability in repeated economic games: comparing trust game decisions to other social trust measures.

Economic games are well-established tools that offer a convenient approach to study social behaviour. Although widely used, recent evidence suggests that decisions made in the context of standard economic games are less predictive of real-world behaviour than previously assumed self-reported questionnaires. A possible explanation for this discrepancy is that economic games decisions in the laboratory are more likely to be influenced by the current situation, while questionnaires are specifically designed to measure people's average behaviour across a long period of time. To test this hypothesis, we performed a longitudinal study where 275 respondents played 16 Trust games every two days within a three-week period, and filled out a questionnaire that measures social trust. This study confirmed the instability of our measure of trust behaviour over time and the substantial stability of questionnaire responses. However, we found a significant association between self-reported social trust and participants' average behaviour in the trust game measured across sessions, but also with participants' behaviour measured only in Session 1. Nevertheless, analysis of behavioural changes in the Trust games over time revealed different behavioural profiles, highlighting how economic games and questionnaires can complement each other in the study of social trust.