A child’s desire to share becomes influenced by social norms around the age of eight


The extensive study – conducted on eight diverse societies across the world – examined children and adults’ behaviour when asked to respond to a set of specific sharing tasks.

Researchers led by Dr Bailey House from the University of York’s Department of Psychology established the sharing patterns of adults in the eight societies, and then worked with children from the same communities to determine how they would split a set of rewards in an experimental sharing task.

Children were given a choice between two options: a generous option which delivered one reward to them and one reward to a stranger.

The selfish option delivered both rewards to the child.

Children under seven largely opted for the selfish choice, while between eight and 12 children in some societies increasingly shared one of the tokens, as children began to follow the usual adult pattern of behaviour in their community.

At about the same age, children in all societies also began to more strongly respond to social norms: they shared more when told that the generous option was “right”, and they shared less when they were told that the selfish option was “right”.

Dr House said: “These results suggest that during middle childhood children become sensitive to culturally-specific information about how to behave.

This “information” may be encoded in local norms, which children acquire through an evolved human psychology for learning and conforming to normative information.

This implies that that we ought to have a universally-developing psychology for becoming sensitive to normative information, and that variation in prosocial behaviour ought to be linked to variation in the content of a society’s social norms, and not to variation in development.”

Dr House studies decision-making and behaviour in adults and children, how these vary across diverse societies, and how they are shaped by both cultural beliefs and evolved adaptations.

For this research, eight different study groups were observed including urban communities in Germany, USA, Argentina and India, as well as rural communities in Ecuador, Vanuatu, and Argentina and hunter-gatherers in Tanzania.

This shows the game used in the study

The Dictator game used in the study. The image is credited to Julie Gatenby, University of York.

Dr House said: “People in all of these groups share extensively, but they are used to doing so in different situations and probably for different reasons.

This is likely why people in these different societies made very different choices when we put them all in the exact same sharing situation.

“One of the implications of the study is that we should start to pay attention not just to what children know but why they start to follow social norms.

The next step is to pose the question of what is happening in a child’s development between the ages of eight and 12 that makes them more responsive to social norms around them.

The goal of the work is to better understand how culture and psychological maturation work together to produce human diversity in cooperation and other behaviours.”

Collaborators on the study included Joan B. Silk from Arizona State University, Patricia Kanngiesser from Frei Universität Berlin and Clark Barrett from University of California, Los Angeles.

The paper entitled, Universal norm psychology leads to society diversity in prosocial behaviour and development, is published in Nature Human Behaviour.

All developed societies draw chronological age boundaries between minors and adults for legal purposes, among them, determining who is permitted to vote, drive, purchase alcohol, and make autonomous medical decisions and, if arrested, who is tried as an adult. In many countries, age 18 is used for most purposes with some exceptions (e.g., consent to research or medical treatment; World Health Organization, 2014).

In others, such as the United States, different ages are used for different matters. For example, although the presumptive age of majority in the U.S. is 18, eligibility for driver’s licensing is generally granted at a younger age, whereas the minimum legal purchase age for alcohol is 21.

The idea that young people lack certain capacities or abilities necessary to assume the responsibilities or enjoy the privileges of adulthood is undoubtedly part of the logic behind differentiating between adults and minors in the law (Woolard & Scott, 2009).

For example, the infancy doctrine, which allows minors who enter into contracts to void them at their discretion, was fashioned to protect minors from their immature judgment as well as adults who might capitalize on youths’ lack of understanding of the consequences of the contract (Preston & Crowther, 2012).

In the early 20th century, legislators established a separate justice system in the U.S. for juveniles (Scott & Steinberg, 2008) based on similar logic, namely, that children differ from adults in ways that require special protection in criminal matters: children suffer from deficient decision-making abilities, which makes them less responsible for their bad acts; children are more amenable to rehabilitation, so they should be reformed, not punished (Davis, Scott, Wadlington, & Whitebread, 2009Woolard & Scott, 2009).

The delineation of a specific age-boundary that separates children from adults has often resulted from practical considerations, without reference to relevant empirical and theoretical foundations (Scott, 2000).

For example, initially there were no age restrictions for driving. As traffic safety became a concern, states began setting a minimum driving age, typically 18 (Mayhew, Fields, & Simpson, 2000).

In the 1920s and 1930s, many states lowered the driving age from 18 to 16 to allow minors to work in occupations requiring a vehicle. As teen driving fatalities increased, many states adopted “graduated driver-licensing” in the 1990s, which lets 16-year-olds drive, but only under certain circumstances (e.g., no other teen passengers in the car; Williams, 1999).

In other instances, political considerations led legislators to draw or change legal boundaries. At the height of the Vietnam War, when the military draft age was 18, the voting age was 21.

Many politicians argued that it was unfair to send 18-year-olds into battle but prohibit them from voting, and Congress amended the Constitution in 1971 to lower the voting age to 18. In response, some states lowered their legal drinking age from 21 to 18 or 19 (Cook & Tauchen, 1984).

Because not all states did this, young people living in places with higher drinking ages would drive across state lines to purchase and consume alcoholic beverages—and then drive back home intoxicated. In 1984, under pressure from the federal government, all states raised the minimum legal drinking age back to 21.

Until recently, developmental psychology has not been an explicit force in determining specific legal age boundaries — when legislators lowered the driving age or raised the drinking age, no one asked whether research on psychological development supported either change.

However, developmental science has gradually become more influential (Steinberg, 2017). In both legal and non-legal venues, experts have weighed in on whether, and at what age, the law should distinguish between adolescents and adults.

But considerable controversy has arisen because scientists have answered this question in different ways, depending on the legal issue involved.

In 2005, when the American Psychological Association (APA) submitted an amicus brief in Roper v. Simmons, the U.S. Supreme Court case that abolished the juvenile death penalty for 16- and 17-year-olds, the APA argued that people younger than 18 lacked the psychological maturity necessary to be held fully responsible for their crimes and, therefore, that they should not be eligible for capital punishment (APA, 2004).

Justice Antonin Scalia, in his dissenting opinion, criticized the APA, because in an earlier case its experts had opined that teenagers should have the right to make decisions about abortion without involving their parents, on the grounds that their decision-making abilities were just as mature as adults’ (APA, 1989).

A group of psychologists argued that this apparent logical inconsistency was actually in keeping with developmental science (Steinberg, Cauffman, Woolard, Graham, & Banich, 2009).

They contended that because different abilities mature along different timetables, adolescents of a given age could be adult-like in some respects but not others.

Based on analyses of data from over 900 individuals between the ages of 10 and 30, they noted that cognitive capacity – the basic cognitive processes supporting the ability to reason logically – matures by 16, whereas psychosocial maturity – the capacity to exercise self-restraint, especially in emotionally-arousing contexts – does not fully mature until several years later. Steinberg et al. (2009) argued that these patterns justify having a lower age boundary for legal decisions that allow deliberation and a higher age boundary for matters pertaining to acts typically made under emotionally arousing circumstances (Scott & Steinberg, 2008).

One way to think about the difference between these capacities and abilities is to distinguish between “cold” cognition and “hot” cognition.

Cold cognition refers to mental processes (such as working memory or response inhibition) employed in situations calling for deliberation in the absence of high levels of emotion (e.g., Figner, Mackinlay, Wilkening, & Weber, 2009).

Hot cognition involves mental processes in affectively charged situations where deliberation is unlikely or difficult. Recent research has borne out this distinction, showing that on response inhibition tasks, young adults (aged 18–21) perform comparably to somewhat older individuals when tested under emotionally neutral conditions but more poorly—and similarly to younger teenagers – when tested under arousing ones (Cohen et al., 2016).

Legal issues pertaining to cold cognition include voting, granting consent for research participation, and making autonomous medical decisions, where the presence of adult consultants and the absence of time pressure impose sufficient external control to minimize the dangers of impulsive decision making (Grisso et al., 2003Hein et al., 2015).

Issues related to hot cognition include driving, consuming alcohol, and criminal behavior; it is easy to make impulsive choices when emotions are aroused, such as when behind the wheel, intoxicated, or committing a crime, behaviors that often occur in the presence of peers during adolescence (Albert & Steinberg, 2011).

Importantly, the developmental trajectories of cold and hot cognition differ. In studies using cold cognitive tasks, performance increases dramatically from childhood to early- or mid-adolescence and then plateaus.

This pattern is demonstrated on tasks of response inhibition (e.g., Huizinga, Dolan, & van der Molen, 2006Luna, Garver, Urban, Lazar, & Sweeney, 2004), cognitive flexibility (e.g., Crone, Ridderinkhof, Worm, Somsen, & van der Molen, 2004), and working memory (e.g., Huizinga et al., 2006Luna et al., 2004Prencipe et al., 2011).

A similar developmental pattern appears in the psycholegal literature as well. For example, younger juveniles (11–15 years) are impaired at significantly higher rates than older adolescents (16–17) on measures of understanding and appreciation of Miranda rights and on other measures of adjudicative competence (Viljoen, Zapf, & Roesch, 2007). But by the time they are 16–17 years old, adolescents and adults score comparably on abilities relevant to competence to stand trial, (Grisso et al., 2003Redlich & Shteynberg, 2016).

In contrast, facets of hot cognition, including sensation seeking (or lack thereof), impulse control, future orientation, and resistance to peer influence, follow a protracted development into adulthood. Sensation seeking, which peaks during adolescence (Steinberg et al., 2008), decreases into the early- to mid-twenties (Harden & Tucker-Drob, 2011Shulman, Harden, Chein, & Steinberg, 2014).

On the other hand, impulse control, future orientation, and resistance to peer influence improve into adulthood in studies employing either self-report assessments (e.g., Harden & Tucker-Drob, 2011Romer, Duckworth, Sznitman, & Park, 2010Steinberg et al., 2009cSteinberg & Monahan, 2007) or behavioral tasks (e.g., Chein, Albert, O’Brien, Uckert, & Steinberg, 2011Cohen et al., 2016Steinberg et al., 2009c).

Similarly, relative to adults, adolescents demonstrate impaired decision making in emotionally arousing contexts, such as when being interrogated by police (e.g., Malloy, Shulman, & Cauffman, 2014).

To the extent that these legal contexts become emotionally arousing as a consequence of external pressures – by friends, family, police, or the adolescent’s own lawyer – adolescents’ decision making lags behind adults’.

Thus, if our laws were more closely aligned with developmental science, age boundaries for matters involving cold cognition might be lower than those involving hot cognition, because effective hot cognition requires both cognitive capacity and psychosocial maturity (e.g., self-restraint).

There is no universally agreed-upon way to measure cognitive capacities or psychosocial maturity. Steinberg et al. (2009) measured cognitive capacity using tests of short-term memory, working memory, and verbal fluency.

These measures of executive functioning undergird goal-directed behavior and higher-order logical reasoning (Diamond, 2013).

Their measure of psychosocial maturity was based on self-reports of traits such as impulse control, sensation seeking, future orientation, and resistance to peer influence.

These measures tap individuals’ ability to restrain themselves in the face of temptations to pursue rewarding, immediately gratifying, socially encouraged, or risky activities.

These measures capture some, but not all, important aspects of cognitive and psychosocial functioning that are relevant to decision making (e.g., neither measure included an index of morality or perspective taking; see Fischer, Stein, & Heikkinen, [2009] and Steinberg, Cauffman, Woolard, Graham, & Banich [2009b] for a response).

It is notable that Steinberg and colleagues’ (2009) measure of cognitive capacity comprised all behavioral tasks, whereas their measure of psychosocial maturity comprised all self-report measures.

These limitations notwithstanding, both constructs include measures that are essential to decision making competence in legal contexts – executive functions facilitate flexible, optimized decision making (Diamond, 2013) whereas elements of psychosocial maturity are strongly tied to what some writers have referred to as “judgment” (e.g., Scott, Reppucci & Woolard, 1995Steinberg & Cauffman, 1996).

University of York
Media Contacts:
Julie Gatenby – University of York
Image Source:
The image is credited to Julie Gatenby, University of York.

Original Research: Closed access
“Universal norm psychology leads to societal diversity in prosocial behaviour and development”. Bailey R. House, Patricia Kanngiesser, H. Clark Barrett, Tanya Broesch, Senay Cebioglu, Alyssa N. Crittenden, Alejandro Erut, Sheina Lew-Levy, Carla Sebastian-Enesco, Andrew Marcus Smith, Süheyla Yilmaz & Joan B. Silk .
Nature Human Behavior doi:10.1038/s41562-019-0734-z.


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