Geert-Jan Will

Testosterone administration modulates moral judgments depending on second-to-fourth digit ratio

Moral judgment involves the interplay of emotions and social cognitions. The male sex-hormone testosterone might play a role in moral reasoning as males are more utilitarian than females in their moral decisions, and high salivary testosterone levels also are associated with utilitarian moral decisions. However, there is no direct evidence for a role of testosterone in moral reasoning. Recent testosterone administration studies show effects on cognitive empathy and social cooperation, which depend on right-hands second-to-fourth (2D:4D) digit ratio, a proxy for prenatal sex-hormone (testosterone-versus-estradiol) priming. Here, in a placebo-controlled within-subjects design using 20 young females we show that 2D:4D predicts 44% of the variance in the effects of testosterone administration on moral judgment. Subjects who show an increase in utilitarian judgments following testosterone administration have significantly higher than average 2D:4D (relatively high prenatal estradiol priming), while subjects showing more deontological judgments following testosterone administration have near-significantly lower 2D:4D (relatively high prenatal testosterone priming). We argue that prenatally-organized differences in aromatase, i.e. conversion from testosterone to estradiol in the brain, might underlie these effects. Our findings suggest that early neurodevelopmental effects of sex steroids play a crucial role in the activational effects of hormones on moral reasoning later in life.

Chronic childhood peer rejection is associated with heightened neural responses to social exclusion during adolescence

This functional Magnetic Resonance Imaging (fMRI) study examined subjective and neural responses to social exclusion in adolescents (age 12–15) who either had a stable accepted (n = 27; 14 males) or a chronic rejected (n = 19; 12 males) status among peers from age 6 to 12. Both groups of adolescents reported similar increases in distress after being excluded in a virtual ball-tossing game (Cyberball), but adolescents with a history of chronic peer rejection showed higher activity in brain regions previously linked to the detection of, and the distress caused by, social exclusion. Specifically, compared with stably accepted adolescents, chronically rejected adolescents displayed: 1) higher activity in the dorsal anterior cingulate cortex (dACC) during social exclusion and 2) higher activity in the dACC and anterior prefrontal cortex when they were incidentally excluded in a social interaction in which they were overall included. These findings demonstrate that chronic childhood peer rejection is associated with heightened neural responses to social exclusion during adolescence, which has implications for understanding the processes through which peer rejection may lead to adverse effects on mental health over time.

Acting on Observed Social Exclusion: Developmental Perspectives on Punishment of Excluders and Compensation of Victims

This study examined punishment of excluders and compensation of victims after observing an instance of social exclusion at various phases of adolescent development. Participants (n = 183; age 9 to 22 years) were first included in a virtual ball-tossing game, Cyberball, and then observed the exclusion of a peer. Subsequently, they played economic games in which they divided money between themselves and the including players, the excluders, and the victim. The results demonstrate a gradual age-related increase in money given to the victim from age 9 to 22 and a gradual decrease in money allocated to the excluders from age 9 to 16 with an increase in 22-year-olds. Affective perspective-taking predicted both compensation of the victim and punishment of the excluders. Taken together these results show that across adolescence individuals sacrifice an increasingly bigger share of their own resources to punish excluders and to compensate victims and that taking the perspective of the victim enhances these decisions.

Effects of Testosterone Administration on Strategic Gambling in Poker Play

Testosterone has been associated with economically egoistic and materialistic behaviors, but -defensibly driven by reputable status seeking- also with economically fair, generous and cooperative behaviors. Problematically, social status and economic resources are inextricably intertwined in humans, thus testosterone’s primal motives are concealed. We critically addressed this issue by performing a placebo-controlled single-dose testosterone administration in young women, who played a game of bluff poker wherein concerns for status and resources collide. The profit-maximizing strategy in this game is to mislead the other players by bluffing randomly (independent of strength of the hand), thus also when holding very poor cards (cold bluffing). The profit-maximizing strategy also dictates the players in this poker game to never call the other players’ bluffs. For reputable-status seeking these materialistic strategies are disadvantageous; firstly, being caught cold bluffing damages one’s reputation by revealing deceptive intent, and secondly, not calling the other players’ bluffs signals submission in blindly tolerating deception. Here we show that testosterone administration in this game of bluff poker significantly reduces random bluffing, as well as cold bluffing, while significantly increasing calling. Our data suggest that testosterone in humans primarily motivates for reputable-status seeking, even when this elicits behaviors that are economically disadvantageous.

Neural correlates of advantageous and disadvantageous inequity in sharing decisions.

Humans have a strong preference for fair distributions of resources. Neuroimaging studies have shown that being treated unfairly coincides with activation in brain regions involved in signaling conflict and negative affect. Less is known about neural responses involved in violating a fairness norm ourselves. Here, we investigated the neural patterns associated with inequity, where participants were asked to choose between an equal split of money and an unequal split that could either maximize their own (advantageous inequity) or another person’s (disadvantageous inequity) earnings. Choosing to divide money unequally, irrespective who benefited from the unequal distribution, was associated with activity in the dorsal anterior cingulate cortex, anterior insula and the dorsolateral prefrontal cortex. Inequity choices that maximized another person’s profits were further associated with activity in the ventral striatum and ventromedial prefrontal cortex. Taken together, our findings show evidence of a common neural pattern associated with both advantageous and disadvantageous inequity in sharing decisions and additional recruitment of neural circuitry previously linked to the computation of subjective value and reward when violating a fairness norm at the benefit of someone else.

Neural correlates of retaliatory and prosocial reactions to social exclusion: Associations with chronic peer rejection

Social exclusion is a distressing experience and can lead to both retaliatory and prosocial reactions toward the sources of exclusion. The way people react to social exclusion has been hypothesized to be shaped through chronic exposure to peer rejection. This functional Magnetic Resonance Imaging study examined associations between chronic peer rejection and retaliatory (i.e. punishing) and prosocial (i.e. forgiving) reactions to social exclusion and the neural processes underlying them. Chronically rejected (n = 19) and stably highly accepted adolescents (n = 27) distributed money between themselves and unknown others who previously included or excluded them in a virtual ball-tossing game (Cyberball). Decreasing the excluders’ monetary profits (i.e., punishment) was associated with increased activity in the ventral striatum, dorsolateral prefrontal cortex (PFC) and parietal cortex in both groups. Compared to stably highly accepted adolescents, chronically rejected adolescents exhibited higher activity in the dorsal striatum and lateral prefrontal cortex – brain regions implicated in cognitive control – when they refrained from punishment and shared their money equally with (i.e. forgave) the excluders. These results provide insights into processes that might underlie the maintenance of peer rejection across development, such as difficulties controlling the urge to retaliate after exclusion.

Some Bullies are More Equal Than Others: Peer Relationships Modulate Altruistic Punishment of Bullies After Observing Ostracism

current study presents a novel experimental design to examine how real-life peer relationships modulate altruistic punishment of bullies and compensation of victims after observed ostracism. Twenty-four participants (age 20) were invited to an experimental session in groups of three classmates and two unfamiliar peers, where they engaged in online interactions with one another. They played a series of virtual ball-tossing games (Cyberball) where they observed the ostracism of a classmate by another classmate and an unfamiliar bully. In between the Cyberball sessions, participants played economic exchange games where they could invest money to increase or decrease the payoffs of the players from the preceding Cyberball session. Participants punished classmate bullies and compensated victims more when they liked the victim more than the bully. Importantly, participants punished familiar bullies less severely than unfamiliar bullies when the familiar bully was better liked than the victim.

Longitudinal links between childhood peer acceptance and the neural correlates of sharing

Abstract Childhood peer acceptance is associated with high levels of prosocial behavior and advanced perspective taking skills. Yet, the neurobiological mechanisms underlying these associations have not been studied. This functional magnetic resonance imaging study examined the neural correlates of sharing decisions in a group of adolescents who had a stable accepted status (n = 27) and a group who had a chronic rejected status (n = 19) across six elementary school grades. Both groups of adolescents played three allocation games in which they could share money with strangers with varying costs and profits to them and the other person. Stably accepted adolescents were more likely to share their money with unknown others than chronically rejected adolescents when sharing was not costly. Neuroimaging analyses showed that stably accepted adolescents, compared to chronically rejected adolescents, exhibited higher levels of activation in the temporo‐parietal junction, posterior superior temporal sulcus, temporal pole, pre‐supplementary motor area, and anterior insula during costly sharing decisions. These findings demonstrate that stable peer acceptance across childhood is associated with heightened activity in brain regions previously linked to perspective taking and the detection of social norm violations during adolescence, and thereby provide insight into processes underlying the widely established links between peer acceptance and prosocial behavior.

A Neurocognitive Perspective on the Development of Social Decision-Making

In this chapter, we review evidence for the hypothesis that developmental changes in cognitive control and perspective taking are crucial in understanding age-related changes in social behavior. Studies that have examined the developmental roots of prosocial behavior using experimental economic games show that other-oriented concern and a preference for fairness emerge early in development. Continued development of intentionality understanding and strategic behavior in bargaining situations suggest that perspective taking and cognitive control undergo extended development and continue to contribute to changes in social behavior well into adolescence. Functional neuroimaging studies have shown that these behavioral changes are accompanied by an increased recruitment of brain regions implicated in cognitive control (e.g., dorsolateral prefrontal cortex) and perspective taking (e.g., temporoparietal junction). Together these studies show that developmental changes in cognitive control and perspective taking and their underlying neural circuitry are associated with progressively more strategic thinking and an increased incorporation of other’s perspectives into social decision-making across development.

Neural Systems Involved In Moral Judgment and Moral Action

For centuries, philosophers have debated whether moral judgments are the product of active deliberation or that intuition drives our decisions about right and wrong. During the last decade and a half, cognitive neuroscientists have stepped into this debate by scanning peoples brains while they make