On Playing with Emotion: A Spatial Evolutionary Variation of the Ultimatum Game.

The Ultimatum Game is a simplistic representation of bargaining processes occurring in social networks. In the standard version of this game, the first player, called the proposer, makes an offer on how to split a certain amount of money. If the second player, called the responder, accepts the offer, the money is divided according to the proposal; if the responder declines the offer, both players receive no money. In this article, an agent-based model is employed to evaluate the performance of five distinct strategies of playing a modified version of this game. A strategy corresponds to instructions on how a player must act as the proposer and as the responder. Here, the strategies are inspired by the following basic emotions: anger, fear, joy, sadness, and surprise. Thus, in the game, each interacting agent is a player endowed with one of these five basic emotions. In the modified version explored in this article, the spatial dimension is taken into account and the survival of the players depends on successful negotiations. Numerical simulations are performed in order to determine which basic emotion dominates the population in terms of prevalence and accumulated money. Information entropy is also computed to assess the time evolution of population diversity and money distribution. From the obtained results, a conjecture on the emergence of the sense of fairness is formulated.

Economic Decisions, Attractiveness, and Intrasexual Competition during Menstrual Cycle in the Ultimatum Game.

Introduction: it seems that, in the phase of greatest fertility, women's intrasexual competition (toward attractive women who live nearby) increases due to access to resources, status, and biologically desirable partners. Objective: to compare the economic decisions (ED) during the ovulatory (OP) and luteal (LP) phases of the menstrual cycle (MC) with exposure to two stimuli: a photograph of a more attractive woman and a photograph of a less attractive woman, through the ultimatum game (UG). Methodology: the research followed a cross-sectional design between subjects to see group differences by contrasting hypotheses. The sampling was probabilistic, with a sample of 100 heterosexual women, students at a public university with an age range of 18 to 24 years, with regular MC, who did not use hormonal contraceptive methods and did not have any endocrine condition. The inverse counting method with confirmation was applied to identify CM phases; and the UG to evaluate the DE. Results: the phases of the MC had no effect on the ED; the women behaved similarly in their decisions, regardless of the phase of the cycle they were in or the type of stimulus to which they were exposed. Conclusion: OP and LP do not affect the ED of women when they are exposed to an attractive stimulus. The discussion is made considering the evolutionary theory of the ovulatory shift hypothesis.

Introducción: parece ser que, en su fase de mayor fertilidad, la competencia intrasexual de la mujer (con mujeres atractivas y que viven cerca) aumenta por el acceso a recursos, estatus y parejas biológicamente deseables. Objetivo: comparar las decisiones económicas (DE) en las fases ovulatoria (FO) y lútea (FL) del ciclo menstrual (CM) con exposición a dos estímulos: fotografía de una mujer de mayor atractivo y fotografía de una mujer de menor atractivo, a través del juego del ultimátum (UG). Metodología: la investigación tuvo un diseño cross-sectional entre sujetos para ver diferencia de grupos mediante contraste de hipótesis. El muestreo fue probabilístico, con una muestra de 100 mujeres heterosexuales, estudiantes de una universidad pública con un rango de edad de 18 a 24 años, con CM regulares, que no usaran métodos anticonceptivos hormonales y no tuvieran ninguna afección endocrina. Resultados: las fases del CM no tuvieron efectos sobre las DE; las mujeres se comportaron de forma similar en sus decisiones, sin importar la fase del ciclo en la que se encontraban o el tipo de estímulo al que fueron expuestas. Conclusión: las FO y FL no afectan las DE de las mujeres cuando son expuestas a un estímulo atractivo. La discusión se hace a la luz de la teoría evolutiva de la hipótesis del cambio ovulatorio.

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.

Taking it easy when playing ultimatum game with a Down syndrome proposer: Effects on behavior and medial frontal negativity.

The ultimatum game (UG) is an endowment sharing game in which a proposer suggests a division of an asset to a recipient, who must accept or reject it. Economic studies showed that despite recipients usually rejecting unfair offers, perception and reaction to unfairness are highly dependent on who is the proposer. Event-related potentials (ERPs) commonly detected in UG games are the medial frontal negativity (MFN), a component detected in recipients facing unfair offers, and the P300, a component related to attentional and memory processes. Given this, we aimed to investigate the behavioral and ERP responses of healthy people playing the UG game with Down syndrome (DS) and typical development (TD) proposers. Nineteen subjects participated in this study. The UG behavioral data were similar to previous studies. ERP analysis showed no MFN in participants facing unfair offers. A higher P300 amplitude was detected when participants faced fair offers from TD compared to DS fair offers. We also found a positive correlation between P300 amplitude for TD offers and self-esteem scale score. Together these findings indicate that insertion of an atypical player in the UG led to changes in participants' perception and expectancy of the game.

Adult-like neuroelectrical response to inequity in children: Evidence from the ultimatum game.

People react aversely when faced with unfair situations, a phenomenon that has been related to an electroencephalographic (EEG) potential known as medial frontal negativity (MFN). To our knowledge, the existence of the MFN in children has not yet been demonstrated. Here, we recorded EEG activity from 15 children playing the ultimatum game (UG) and who afterward performed a recognition task, in order to assess whether they could recognize the unfair and fair (familiar) proposers among unfamiliar faces. During the recognition task, we also acquired pupil dilation data to investigate subconscious recognition processes. A typical (adult-like) MFN component was detected in reaction to unfair proposals. We found a positive correlation between reaction time and empathy, as well as a negative correlation between reaction time and systematic reasoning scores. Finally, we detected a significant difference in pupil dilation in response to unfamiliar faces versus UG proposers. Our data provide the first evidence of MFN in children, which appears to index similar neurophysiological phenomena as in adults. Also, reaction time to fair proposals seems to be related to individual traits, as represented by empathy and systematizing. Our pupil dilation data provide evidence that automatic responses to faces did not index fairness, but familiarity. These findings have implications for our understanding of social development in typically developing children.

El rol de la envidia benigna y maligna en la toma de decisiones estratégicas / The role of benign and malicious envy in making strategic decisions

Este trabajo se propone examinar la influencia de las envidias benigna y maligna en las ofertas del proponente en condición de envidiado y envidioso en el Juego del Ultimátum en 172 estudiantes universitarios de Córdoba, Argentina. Se empleó un diseño factorial interindividual 2 (tipo de envidia: maligna y benigna) X 2 (condición del participante: envidiado y envidioso) con un grupo adicional de control absoluto. Se compararon las ofertas en el Juego del Ultimátum según la condición experimental. No se observaron diferencias estadísticamente significativas entre las distintas condiciones. Sin embargo, se observó que la preocupación por ser envidiado se relacionó positivamente con las ofertas en el juego.

This study aimed to examine the influence of benign and malicious envy upon offers from proponents with envious and envied status in the Ultimatum Game. Participants were 172 university students from Cordoba (Argentina). A factorial inter-subject 2 (type envy: benign and malicious) 3 2 (condition of the participant: envied and envious) design was used, with an additional absolute control group. Offers in the Ultimatum Game were compared according to experimental condition. No statistically significant differences were observed between the different conditions. Nevertheless, the fear of being envied was positively associated with offers in the Ultimatum Game.

Abnormal brain responses to social fairness in depression: an fMRI study using the Ultimatum Game.

BACKGROUND: Depression is a prevalent disorder that significantly affects the social functioning and interpersonal relationships of individuals. This highlights the need for investigation of the neural mechanisms underlying these social difficulties. Investigation of social exchanges has traditionally been challenging as such interactions are difficult to quantify. Recently, however, neuroeconomic approaches that combine multiplayer behavioural economic paradigms and neuroimaging have provided a framework to operationalize and quantify the study of social interactions and the associated neural substrates. METHOD: We investigated brain activation using functional magnetic resonance imaging (fMRI) in unmedicated depressed participants (n = 25) and matched healthy controls (n = 25). During scanning, participants played a behavioural economic paradigm, the Ultimatum Game (UG). In this task, participants accept or reject monetary offers from other players. RESULTS: In comparison to controls, depressed participants reported decreased levels of happiness in response to 'fair' offers. With increasing fairness of offers, controls activated the nucleus accumbens and the dorsal caudate, regions that have been reported to process social information and responses to rewards. By contrast, participants with depression failed to activate these regions with increasing fairness, with the lack of nucleus accumbens activation correlating with increased anhedonia symptoms. Depressed participants also showed a diminished response to increasing unfairness of offers in the medial occipital lobe. CONCLUSIONS: Our findings suggest that depressed individuals differ from healthy controls in the neural substrates involved with processing social information. In depression, the nucleus accumbens and dorsal caudate may underlie abnormalities in processing information linked to the fairness and rewarding aspects of other people's decisions.