Behavioral and neuronal determinants of negative reciprocity in the ultimatum game

Empathy incites a stable prosocial decision bias

Empathy toward suffering individuals serves as potent driver for prosocial behavior. However, it remains unclear whether prosociality induced by empathy for another person's pain persists once that person's suffering diminishes. To test this, participants underwent functional magnetic resonance imaging while performing a binary social decision task that involved allocation of points to themselves and another person. In block one, participants completed the task after witnessing frequent painful stimulation of the other person, and in block two, after observing low frequency of painful stimulation. Drift-diffusion modeling revealed an increased initial bias toward making prosocial decisions in the first block compared with baseline that persisted in the second block. These results were replicated in an independent behavioral study. An additional control study showed that this effect may be specific to empathy as stability was not evident when prosocial decisions were driven by a social norm such as reciprocity. Increased neural activation in dorsomedial prefrontal cortex was linked to empathic concern after witnessing frequent pain and to a general prosocial decision bias after witnessing rare pain. Altogether, our findings show that empathy for pain elicits a stable inclination toward making prosocial decisions even as their suffering diminishes.

A premium for positive social interest and attractive voices in the acceptability of unfair offers? An ERP study

Although the attractiveness of voices plays an important role in social interactions, it is unclear how voice attractiveness and social interest influence social decision-making. Here, we combined the ultimatum game with recording event-related brain potentials (ERPs) and examined the effect of attractive versus unattractive voices of the proposers, expressing positive versus negative social interest ("I like you" vs. "I don't like you"), on the acceptance of the proposal. Overall, fair offers were accepted at significantly higher rates than unfair offers, and high voice attractiveness increased acceptance rates for all proposals. In ERPs in response to the voices, their attractiveness and expressed social interests yielded early additive effects in the N1 component, followed by interactions in the subsequent P2, P3 and N400 components. More importantly, unfair offers elicited a larger Medial Frontal Negativity (MFN) than fair offers but only when the proposer's voice was unattractive or when the voice carried positive social interest. These results suggest that both voice attractiveness and social interest moderate social decision-making and there is a similar "beauty premium" for voices as for faces.

The impact of facial attractiveness and alleged personality traits on fairness decisions in the ultimatum game: Evidence from ERPs

In the mind of the beholder the personality and facial attractiveness of others are interrelated. However, how these specific properties are processed in the neurocognitive system and interact with each other while economic decisions are made is not well understood. Here, we combined the ultimatum game with EEG technology, to investigate how alleged personality traits and the perceived facial attractiveness of proposers of fair and unfair offers influence their acceptance by the responders. As expected, acceptance rate was higher for fair than unfair allocations. Overall, responders were more likely to accept proposals from individuals with higher facial attractiveness and with more positive personality traits. In ERPs, words denoting negative personality traits elicited larger P2 components than positive trait words, and more attractive faces elicited larger LPC amplitudes. Replicating previous findings, FRN amplitudes were larger to unfair than to fair allocations. This effect was diminished if the proposer's faces were attractive or associated with positive personality traits. Hence, facial attractiveness and the valence of personality traits seem to be evaluated independently and at different time points. Subsequent decision making about unfair offers is similarly influenced by high attractiveness and positive personality of the proposer, diminishing the negative response normally elicited by "unfair" proposals, possibly due a "reward" effect. In the ERPs to the proposals the effect of positive personality and attractiveness were seen in the FRN and P300 components but for positive personality traits the effect even preceded the FRN effect. Altogether, the present results indicate that both high facial attractiveness and alleged positive personality mitigate the effects of unfair proposals, with temporally overlapping but independent neurocognitive correlates.

How and when social evaluative feedback is processed in the brain: A systematic review on ERP studies

Social evaluative feedback informs the receiver of the other's views, which may contain judgments of personality-related traits and/or the level of likability. Such kinds of social evaluative feedback are of particular importance to humans. Event-related potentials (ERPs) can directly measure where in the processing stream feedback valence, expectancy, or contextual relevance modulate information processing. This review provides an overview and systematization of studies and early, mid-latency, and late ERP effects. Early effects were inconsistently reported for all factors. Feedback valence effects are more consistently reported for specific mid-latency ERPs (Reward Positivity, RewP, and Early Posterior Negativity, EPN) and late positivities (P3 and Late Positive Potential, LPP). Unexpected feedback consistently increased the Feedback Related Negativity (FRN) and, less consistently, decreased P3 amplitudes. Contextual relevance of the sender (e.g., human vs computer sender) or self-relatedness increased mid-latency to late ERPs. Interactions between valence and other factors were less often found, arising during mid-latency stages, where most consistent interactions showed larger EPN and P3 amplitude differences for valent feedback in a more relevant context. The ERP findings highlight that social evaluative feedback is consistently differentiated during mid-latency processing stages. The review discusses the relevance of findings, possible shortcomings of different experimental designs, and open questions. Furthermore, we suggest concrete venues for future research.

Event-related potentials during the ultimatum game in people with symptoms of depression and/or social anxiety

Depression and social anxiety are common disorders that have a profound impact on social functioning. The need for studying the neural substrates of social interactions in mental disorders using interactive tasks has been emphasized. The field of neuroeconomics, which combines neuroscience techniques and behavioral economics multiplayer tasks such as the Ultimatum Game (UG), can contribute in this direction. We assessed emotions, behavior, and Event-Related Potentials in participants with depression and/or social anxiety symptoms (MD/SA, n = 63, 57 females) and healthy controls (n = 72, 67 females), while they played the UG. In this task, participants received fair, mid-value, and unfair offers from other players. Mixed linear models were implemented to assess trial level changes in neural activity. The MD/SA group reported higher levels of sadness in response to mid-value and unfair offers compared to controls. In controls, the Medial Frontal Negativity associated with fair offers increased over time, while this dynamic was not observed in the MD/SA group. The MD/SA group showed a decreased P3/LPP in all offers, compared to controls. These results indicate an enhanced negative emotional response to unfairness in the MD/SA group. Neural results reveal a blunted response over time to positive social stimuli in the MD/SA group. Moreover, between-group differences in P3/LPP may relate to a reduced saliency of offers and/or to a reduced availability of resources for processing incoming stimuli in the MD/SA group. Findings may shed light into the neural substrates of social difficulties in these disorders.

Moral transgression modulates fairness considerations in the ultimatum game: Evidence from ERP and EEG data

People tend to dislike and punish unfair behaviors in social interactions, and this disposition may be moderated by the characteristics of their interaction partner. We used a modified ultimatum game (UG) to investigate players' responses to fair and unfair offers from proposers described as having performed either a moral transgression or a neutral behavior, and recorded an electroencephalogram. The participants' behavior in the UG suggests that people quickly demand more fairness from proposers who have committed moral transgressions rather than neutral behavior. Event-related potentials (ERPs) revealed a significant effect of offer type and of proposer type on P300 activity. The prestimulus α-oscillation power in the neutral behavior condition was significantly lower than that in the moral transgression condition. The post-stimulus β-event-related synchronization (β-ERS) was larger for the moral transgression condition than the neutral behavior condition in response to the least fair offers, and larger for neutral behavior than the moral transgression condition in response to the fairest offers. In summary, β-ERS was influenced by both proposer type and offer type, which revealed different neural responses to the offer from either a morally transgressive or a neutral behavior proposer.

Basic Evaluation Process and some Associated Phenomena, Such as Emotions and Reactive Defense of Beliefs

The goal of this article is to develop a theory about the evaluation process in order to offer a perspective that is potentially capable of parsimoniously explaining a series of phenomena. I argue that not only is categorical thinking shared by humans and other animals, but also certain types of categorization ("what is something?"; "what end to seek?"; "by what means?"; "was there success in accomplishing the end?"), which I understand to be aligned in a mat of categorizations, constituting what I call the basic evaluation process. I hypothesize that within this evaluation process there are five options for basic categorizations pathways (BCP), namely: "identification of patterns in the novelty"; "acquisition of the benefit", "promotion of the good of the other"; "elimination of the threat"; and "escape the threat". Thus, the basic evaluation process would follow a certain path depending on the type of categorization "what is something?" performed ("a novelty", "a benefit", "an ally (or potential ally) in difficulty", "a threat that can be eliminated", or "a threat that cannot be eliminated"). Finally, I defend the idea that if the mental architecture of humans is composed of ancestral structures such as BCPs, it is then possible to locate BCP as being at the root of innumerable subjective phenomena of our species.

The impact of social comparison and (un)fairness on upstream indirect reciprocity: Evidence from ERP

Event-related potential (ERP) technology and the dictator game paradigm are used to explore the formation mechanism of upstream indirect reciprocity behaviors. We design a within subject experiment of 3 (social comparison: upward versus parallel versus downward) × 2 (treatment: fair versus unfair) involving 49 subjects. In the first round of allocations, subjects are forced to accept a monetary amount allocated to them by another player. In the second round, subjects assume the role of allocator and divide a monetary amount between themselves and a third party. Our results show the following: 1) Having received fair treatment from someone else, individuals engaged in downward comparison are more inclined to reciprocate the fairness they had received to a third party compared to individuals in parallel and upward comparison conditions. If individuals receive unfair treatment, they tend to repeat this behavior to a third party regardless of which social comparison condition they are in; 2) Under the condition of upward comparison, individuals receiving unfair treatment exhibit greater FRN amplitude and less P300 amplitude, but in parallel and downward comparison conditions, there is no significance in FRN and P300 amplitude between individuals receiving fair and unfair treatment.

Electrophysiological Correlates of Social Decision-making: An EEG Investigation of a Modified Ultimatum Game

Cooperation behaviors during social decision-making have been shown to be sensitive to manipulations of context. However, it remains unclear how aspects of context in dynamic social interactions, such as observed nonverbal behaviors, may modulate cooperation decisions and the associated neural mechanisms. In this study, participants responded to offers from proposers to split $10 in an Ultimatum Game following observation of proposer approach (friendly) or avoidance (nonfriendly) behaviors, displayed by dynamic whole-body animated avatars, or following a nonsocial interaction control condition. As expected, behavioral results showed that participants tended to have greater acceptance rates for unfair offers following observed nonverbal social interactions with proposers compared with control, suggesting an enhancing effect of social interactions on cooperative decisions. ERP results showed greater N1 and N2 responses at the beginning of social interaction conditions compared with control, and greater sustained and late positivity responses for observed approach and avoidance proposer behaviors compared with control. Event-related spectral perturbation (ERSP) results showed differential sensitivity within theta, alpha, and beta bands during observation of social interactions and offers that was associated with subsequent decision behaviors. Together, these results point to the impact of proposers' nonverbal behaviors on subsequent cooperation decisions at both behavioral and neural levels. The ERP and ERSP findings suggest modulated attention, monitoring, and processing of biological motion during the observed nonverbal social interactions, influencing the participants' responses to offers. These findings shed light on electrophysiological correlates of response to observed social interactions that predict subsequent social decisions.

Champ versus Chump: Viewing an Opponent’s Face Engages Attention but Not Reward Systems

When we play competitive games, the opponents that we face act as predictors of the outcome of the game. For instance, if you are an average chess player and you face a Grandmaster, you anticipate a loss. Framed in a reinforcement learning perspective, our opponents can be thought of as predictors of rewards and punishments. The present study investigates whether facing an opponent would be processed as a reward or punishment depending on the level of difficulty the opponent poses. Participants played Rock, Paper, Scissors against three computer opponents while electroencephalographic (EEG) data was recorded. In a key manipulation, one opponent (HARD) was programmed to win most often, another (EASY) was made to lose most often, and the third (AVERAGE) had equiprobable outcomes of wins, losses, and ties. Through practice, participants learned to anticipate the relative challenge of a game based on the opponent they were facing that round. An analysis of our EEG data revealed that winning outcomes elicited a reward positivity relative to losing outcomes. Interestingly, our analysis of the predictive cues (i.e., the opponents’ faces) demonstrated that attentional engagement (P3a) was contextually sensitive to anticipated game difficulty. As such, our results for the predictive cue are contrary to what one might expect for a reinforcement model associated with predicted reward, but rather demonstrate that the neural response to the predictive cue was encoding the level of engagement with the opponent as opposed to value relative to the anticipated outcome.

Determinants and modulators of human social decisions

Social decision making is a highly complex process that involves diverse cognitive mechanisms, and it is driven by the precise processing of information from both the environment and from the internal state. On the one hand, successful social decisions require close monitoring of others' behavior, in order to track their intentions; this can guide not only decisions involving other people, but also one's own choices and preferences. On the other hand, internal states such as own reward or changes in hormonal and neurotransmitter states shape social decisions and their underlying neural function. Here, we review the current literature on modulators and determinants of human social decisions.

The Benefit of Gratitude: Trait Gratitude Is Associated With Effective Economic Decision-Making in the Ultimatum Game

The current research investigated the role of gratitude in economic decisions about offers that vary in fairness yet benefit both parties if accepted. Participants completed a trait/dispositional gratitude measure and then were randomly assigned to recall either an event that made them feel grateful (i.e., induced gratitude condition) or the events of a typical day (i.e., neutral condition). After the gratitude induction task, participants played the ultimatum game (UG), deciding whether to accept or reject fair offers (i.e., proposer: responder ratio $5:5) and unfair offers (i.e., proposer: responder ratios of $9:1, $8:2, or $7:3) from different proposers. Results showed that trait gratitude was positively correlated with respondents’ acceptance of unfair offers. However, experimentally induced momentary gratitude did not influence acceptance of unfair offers. The trait or disposition to be grateful involves the enduring capacity across different types of situations and benefactors to see the good that is present, even when that benefit is small. Accordingly, dispositional gratitude – but not momentarily induced gratitude – was associated with a greater propensity to accept even the small benefits within unfair offers which otherwise pose barriers to making the effective economic decision of accepting offers regardless of their relative size.

Social value orientation modulates fairness processing during social decision-making: evidence from behavior and brain potentials

Social value orientation (SVO) characterizes stable individual differences by an inherent sense of fairness in outcome allocations. Using the event-related potential (ERP), this study investigated differences in fairness decision-making behavior and neural bases between individuals with prosocial and proself orientations using the Ultimatum Game (UG). Behavioral results indicated that prosocials were more prone to rejecting unfair offers with stronger negative emotional reactions compared with proselfs. ERP results revealed that prosocials showed a larger P2 when receiving fair offers than unfair ones in a very early processing stage, whereas such effect was absent in proselfs. In later processing stages, although both groups were sensitive to fairness as reflected by an enhanced medial frontal negativity (MFN) for unfair offers and a larger P3 for fair offers, prosocials exhibited a stronger fairness effect on these ERP components relative to proselfs. Furthermore, the fairness effect on the MFN mediated the SVO effect on rejecting unfair offers. Findings regarding emotional experiences, behavioral patterns and ERPs provide compelling evidence that SVO modulates fairness processing in social decision-making, whereas differences in neural responses to unfair vs fair offers as evidenced by the MFN appear to play important roles in the SVO effect on behavioral responses to unfairness.

Generosity in dictator game and social value orientation predicted the type of costly punishment in ultimatum game

The current study investigated two types of punishment (prosocial and proself punishment) in the ultimatum game (UG) and examined the impact of individuals' prosocial orientation on the costly punishment in the UG in a representative sample of Chinese undergraduate students (N = 344). The prosocial orientation was measured with individuals' performance in the dictator game (DG), social value orientation (SVO), and the personal norm of reciprocity. Prosocial and proself punishers were established with responses in advantage and disadvantage offers in the UG. Results showed that prosocial and proself punishers coexisted in the UG, and prosocial punishers were more likely to be prosocial in SVO and allocated more resources to the recipient in the DG than proself punishers, but differences in positive/negative reciprocity between prosocial and proself punishers were not found. Further regression analysis found that SVO type and generosity in the DG could predict the type of punishers in the UG, but not positive/negative reciprocity. These findings indicate that individuals rejecting unfair offers in the UG may be motivated by either prosocial motivation with strict fairness concern (prosocial punishment) or selfish motivation with maximizing self-interest concern (proself punishment). Moreover, SVO type and generosity in the DG might be effective measures to discriminate prosocial and proself punishers in the UG.

Monetary payoffs modulate reciprocity expectations in outcome evaluations: An event-related potential study

Choosing cooperation or aggression relies on reciprocity preferences which refer to the tendency of an individual to return cooperative or aggressive action for cooperative or aggressive action (i.e., positive or negative reciprocity preference). The reciprocity preference is positively correlated with reciprocity expectation, wherein individuals with stronger reciprocity preferences may have higher expectations than future cooperative or aggressive behavior should be delivered by beneficiaries (positive reciprocity expectation) or victims (negative reciprocity expectation). Although previous studies have demonstrated that the presence of monetary payoffs enhances reciprocity preferences, the modulation of monetary payoffs in reciprocity expectations remains unclear. Using event-related potentials (ERPs), we examined how monetary payoffs modulated reciprocity expectations by adopting the Chicken game. Participants were asked to choose between cooperation and aggression with a putative opponent in the Chicken game involving the monetary (vs. non-monetary) payoffs. Participants' electroencephalogram (EEG) was recorded when they saw the opponent's cooperative or aggressive decision. Results showed that compared to the non-monetary payoff trials, the feedback-related negativity (FRN) effect in response to the opponent's decisions was stronger following the participant's aggressive decision in the monetary payoff trials, whereas P3 was insensitive to monetary payoffs. These findings suggest that monetary payoffs heighten expectations of negative reciprocity at the earlier and automatic outcome processing stage.

Late Frontal Negativity Discriminates Outcomes and Intentions in Trust-Repayment Behavior

Altruism (a costly action that benefits others) and reciprocity (the repayment of acts in kind) differ in that the former expresses preferences about the outcome of a social interaction, whereas the latter requires, in addition, ascribing intentions to others. Interestingly, an individual's behavior and neurophysiological activity under outcome- versus intention-based interactions has not been compared directly using different endowments in the same subject and during the same session. Here, we used a mixed version of the Dictator and the Investment games, together with electroencephalography, to uncover a subject's behavior and brain activity when challenged with endowments of different sizes in contexts that call for an altruistic (outcome-based) versus a reciprocal (intention-based) response. We found that subjects displayed positive or negative reciprocity (reciprocal responses greater or smaller than that for altruism, respectively) depending on the amount of trust they received. Furthermore, a subject's late frontal negativity differed between conditions, predicting responses to trust in intentions-based trials. Finally, brain regions related with mentalizing and cognitive control were the cortical sources of this activity. Thus, our work disentangles the behavioral components present in the repayment of trust, and sheds light on the neural activity underlying the integration of outcomes and perceived intentions in human economic interactions.

Learning to trust a face: The time course of brain activation during a money game

Evidence shows that human faces can rapidly produce impressions of trust or distrust on the basis of their facial features. However, trust is also built through repeated interactions in which an opposite party acts positively towards the subject in a consistent way. The dynamics of cortical activation of this form of interactively-experienced trust is unclear. The current study therefore investigated the electrophysiological response to trust/distrust, arising through interactions in an investment game. Using an ERP paradigm, participants took part in a money game in which they chose to entrust different amounts to fictitious players. Some of these players were associated with the higher probability of a positive outcome (trustworthy behaviour), others were associated with a higher negative outcome (untrustworthy behaviour), and yet others were neutral. Over the course of the game, a strong central positivity emerged between 450 and 650 ms for trustworthy faces, compared to both neutral and untrustworthy players. This time period thus reflects the window during which the trustworthiness of a face is processed, when based on prior interaction. In addition, by evidencing ERP modifications for trustworthy faces alone, these findings suggest that the "default mode" of processing is initially biased towards distrust.

Costless and Costly Prosociality: Correspondence Among Personality Traits, Economic Preferences, and Real-World Prosociality

Prosociality can either be costly (e.g., donating to charity) or costless (e.g., posthumous organ donation). Whereas links between personality and costly prosociality have been explored, links with costless prosociality and personality are at present unknown. We address this in two studies: Study 1 ( N = 200) confirms the distinction between costless and costly prosociality based on willingness to engage with health and nonhealth prosociality. Study 2, using data from four samples (student and community; N = 733) shows, across incentivized and hypothetical economic games to assess costless (generosity game [GG]) and costly (dictator game [DG]) prosociality, that organ donor behavior was linked to greater allocations in the GG and that charity/volunteering behavior was linked to greater allocations in the DG. Costless and costly prosocialities are associated with different personality traits (e.g., costly with politeness and compassion and costless with intellect). Implications for cooperative phenotypes and recruiting organ donors are discussed.

Give Me a Chance! Sense of Opportunity Inequality Affects Brain Responses to Outcome Evaluation in a Social Competitive Context: An Event-Related Potential Study

People are strongly motivated to pursue social equality during social interactions. Previous studies have shown that outcome equality influences the neural activities of monetary feedback processing in socioeconomic games; however, it remains unclear whether perception of opportunity equality affects outcome evaluation even when outcomes are maintained equal. The current study investigated the electrophysiological activities of outcome evaluation in different instructed opportunity equality conditions with event-related potentials (ERPs). Participants were asked to play a competitive dice game against an opponent to win money. Opportunity equality was manipulated in three conditions, depending on whether participants were allowed the opportunity to throw less, equal, or more dice compared to their opponents. Although participants received a winning outcome with approximately 50% chance in all equality conditions, they selectively exhibited sensitivity to the less-dice condition by reporting stronger feelings of unfairness and unpleasantness than in the equal and more-dice conditions. In line with the behavioral results, larger reward positivity amplitudes were elicited by the monetary outcome in the less-dice condition than in the other two conditions, reflecting intensified reward prediction error (RPE) signals under negative emotional arousal. Further, P3 amplitudes were enhanced following reward feedback only in the unequal conditions, perhaps due to the high-level motivational and affective processing associated with resolving conflict between social norms and self-interest. The present findings elucidate the complex temporal course of outcome evaluation processes in different opportunity equality conditions.

No Robust Association between Static Markers of Testosterone and Facets of Socio-Economic Decision Making

Digit ratio (2D:4D) and facial width-to-height ratio (WHR) are supposedly static indicators of testosterone exposition during prenatal and pubertal lifetime, respectively. Both measures have been linked to aggressive and assertive behavior in laboratory economic games, as well as in real world scenarios. Most of the research-often limited to male subjects-considers the associations between these behaviors, traits, and hormonal markers separately for 2D:4D and WHR. Reported associations are weak and volatile. In the present study we had independent raters assess 2D:4D and WHR in a sample of N = 175 participants who played the ultimatum game (UG). Respondent behavior in UG captures the tendency to reject unfair offers (negative reciprocity). If unfair UG offers are seen as provocations, then individuals with stronger testosterone exposition may be more prone to reject such offers. Economists argue that negative reciprocity reflects altruistic punishment, since the rejecting individual is sacrificing own resources. However, recent studies suggest that self-interest, in terms of status defense plays a substantial role in decisions to reject unfair offers. We also assessed social preferences by social value orientation and assertiveness via self-report. By applying structural equation modeling we estimated the latent level association of 2D:4D and WHR with negative reciprocity, assertiveness and prosociality in both sexes. Results revealed no robust association between any of the trait measures and hormonal markers. The measures of 2D:4D and WHR were not related with each other. Multigroup models based on sex suggested invariance of factor loadings allowing to compare hormone-behavior relationships of females and males. Only when collapsing across sex greater WHR was weakly associated with assertiveness, suggesting that individuals with wider faces tend to express greater status defense. Only the right hand 2D:4D was weakly associated with prosocial behavior, indicating that individuals with lower prenatal testosterone exposure are more cooperative. Rejection behavior in UG was not related with 2D:4D nor WHR in any of the models. There were also no curvilinear associations between 2D:4D and prosociality as theorized in the literature. Our results suggest that previous studies over-estimated the role of static markers of testosterone in accounting for aggression and competition behavior in males.

Differences in Social Decision-Making between Proposers and Responders during the Ultimatum Game: An EEG Study

The Ultimatum Game (UG) is a typical paradigm to investigate social decision-making. Although the behavior of humans in this task is already well established, the underlying brain processes remain poorly understood. Previous investigations using event-related potentials (ERPs) revealed three major components related to cognitive processes in participants engaged in the responder condition, the early ERP component P2, the feedback-related negativity (FRN) and a late positive wave (late positive component, LPC). However, the comparison of the ERP waveforms between the responder and proposer conditions has never been studied. Therefore, to investigate condition-related electrophysiological changes, we applied the UG paradigm and compared parameters of the P2, LPC and FRN components in twenty healthy participants. For the responder condition, we found a significantly decreased amplitude and delayed latency for the P2 component, whereas the mean amplitudes of the LPC and FRN increased compared to the proposer condition. Additionally, the proposer condition elicited an early component consisting of a negative deflection around 190 ms, in the upward slope of the P2, probably as a result of early conflict-related processing. Using independent component analysis (ICA), we extracted one functional component time-locked to this deflection, and with source reconstruction (LAURA) we found the anterior cingulate cortex (ACC) as one of the underlying sources. Overall, our findings indicate that intensity and time-course of neuronal systems engaged in the decision-making processes diverge between both UG conditions, suggesting differential cognitive processes. Understanding the electrophysiological bases of decision-making and social interactions in controls could be useful to further detect which steps are impaired in psychiatric patients in their ability to attribute mental states (such as beliefs, intents, or desires) to oneself and others. This ability is called mentalizing (also known as theory of mind).

Will the Real Factors of Prosociality Please Stand Up? A Comment on Böckler, Tusche, and Singer (2016)

Based on a large individual differences study, Böckler, Tusche, and Singer aimed to develop and psychometrically evaluate measurement procedures that capture individual differences in multiple facets of human prosociality. Böckler et al. claimed that they identified four reliable and method-independent subcomponents of human prosociality: altruistically motivated prosocial behavior, norm-motivated prosocial behavior, strategically motivated prosocial behavior, and self-reported prosocial behavior. We show that this claim is not supported by the data. The abnormalities of the factor solution are visible in reported standardized loadings much larger than unity and negative residual variances at the indicator level. Additionally, the strong dispersion in factor loadings reported in the article hinders factor interpretation. We reanalyze the correlation matrices and propose a model with one overarching prosociality factor and a specific factor for game-theoretical conflicts. This simpler model is a more sustainable representation of prosocial behavior.

Processing of fair and unfair offers in the ultimatum game under social observation

Social context influences social decisions and outcome processing, partially depending on inter-individual differences. The present study investigated social context-dependent modulation of behavior and feedback processing in the ultimatum game (UG) in relation to inter-individual differences in social anxiety. Thirty-two healthy adults completed the UG both under social observation and without observation. Offers were allegedly either randomly generated by the computer or drawn from a pool of offers from previous human players. Overall, fewer unfair than fair offers were accepted. Observation decreased acceptance rates for unfair offers. The feedback-locked feedback-related negativity (FRN) but not the P3 was modulated by observation and fairness, with stronger differential coding of unfair/fair under observation. This effect was strongly correlated with individual levels of social anxiety, with higher levels associated with stronger differential fairness coding in the FRN under observation. Behavioral findings support negative reciprocity in the UG, suggesting that (implicit) social norms overwrite explicit task instructions even in the absence of (alleged) social interaction. Observation enhances this effect. Fairness coding in the FRN was modulated by observation as a function of social anxiety, supporting the notion that altered sensitivity to equality in a social context may contribute to social avoidance in socially anxious individuals.