"It seems like people accept you more if you’re, like, a dangerous driver or something. If there is a line of cars going down the road and the other lane is clear and you pass eight cars at once, everybody likes that. . . . If my friends are with me in the car, or if there are a lot of people in the line, I would do it, but if I’m by myself and I didn’t know anybody, then I wouldn’t do it. That’s no fun."

—Anonymous teenager, as quoted in The Culture of Adolescent Risk-Taking (Lightfoot, 1997, p. 10)

Introduction

It is well established that adolescents are more likely than children or adults to take risks, as evinced by elevated rates of experimentation with alcohol, tobacco, and drugs, unprotected sexual activity, violent and nonviolent crime, and reckless driving (Steinberg, 2008). Early research efforts to identify the distinguishing cognitive immaturity underlying adolescents’ heightened risk-taking propensity bore little fruit. A litany of carefully controlled laboratory experiments contrasted adolescent and adult capacities to perceive and process fundamental components of risk information, but found that adolescents possess the knowledge, values, and processing efficiency to evaluate risky decisions as competently as adults do (Reyna & Farley, 2006).

If adolescents are so risk prone in the real world, why do they appear so risk averse in the lab? We propose that the answer to this question is nicely illustrated by the American teenager quoted above: “If I’m by myself and I didn’t know anybody, then I wouldn’t do it. That’s no fun.” If adolescents made all of their decisions involving drinking, driving, dalliances, and delinquency in the cool isolation of an experimenter’s testing room, those decisions would likely be as risk averse as those of adults. But therein lies the rub: Teenagers spend a remarkable amount of time in the company of other teenagers. In this article, we describe a new wave of research on the neurobehavioral substrates of adolescent decision making in peer contexts suggesting that the company of other teenagers fundamentally alters the calculus of adolescent risk taking.

Peer Influences on Adolescent Risk Behavior

Consistent with self-reports of lower resistance to peer influence among adolescents than among adults (Steinberg & Monahan, 2007), observational data point to peer influence as a primary contextual factor contributing to adolescents’ heightened tendency to make risky decisions. For instance, crime statistics indicate that adolescents typically commit delinquent acts in peer groups, whereas adults more frequently offend alone (Zimring, 1998). Furthermore, one of the strongest predictors of delinquent behavior in adolescence is affiliation with delinquent peers, an association that has been attributed in varying degrees to peer socialization (e.g., deviancy training; Dishion, Bullock, & Granic, 2002) and friendship choices, in which risk-taking adolescents naturally gravitate toward one another (e.g., Bauman & Ennett, 1996). Given the difficulty of distinguishing between these causal alternatives using correlational data, our lab has pursued a program of experimental research directly comparing the behavior of adolescents and adults when making decisions either alone or in the presence of peers.

In the first experimental study to examine age differences in the effect of peer context on risky decision making (Gardner & Steinberg, 2005), early adolescents (mean age = 14), late adolescents (mean age = 19), and adults (mean age = 37) were tested on a computerized driving task called the Chicken Game, which challenges the driver to advance a vehicle as far as possible on a driving course while avoiding crashing into a wall that could appear, without warning, on the course at any point. Peer context was manipulated by randomly assigning participants to play the game either alone or with two same-aged peers in the room. When tested alone, participants in each of the three age groups engaged in a comparable amount of risk taking. In contrast, early adolescents scored twice as high on an index of risky driving when tested with their peers in the room than when tested alone, whereas late adolescents’ driving was approximately 50% riskier in the presence of peers, and adults showed no difference in risky driving related to social context. The ongoing goal of our research program is to further specify the behavioral and neural mechanisms of this peer effect on adolescent risk taking.

A Neurodevelopmental Model of Peer Influences on Adolescent Decision Making

Building on extensive evidence demonstrating maturational changes in brain structure and function occurring across the second decade of life (and frequently beyond), we have advanced a neurodevelopmental account of heightened susceptibility to peer influence among adolescents (Albert & Steinberg, 2011; Steinberg, 2008). In brief, we propose that, among adolescents more than adults, the presence of peers “primes” a reward-sensitive motivational state that increases the subjective value of immediately available rewards and thereby increases preferences for the short-term benefits of risky choices over the long-term value of safe alternatives. Although a comprehensive presentation of the behavioral and neuroscientific evidence underlying this hypothesis is beyond our current scope (but see Albert & Steinberg, 2011), a brief review of three fundamental assumptions of this model will set the stage for a description of our peer-influence studies.

First, decisions are a product of both cognitive and affective input, even when affect is unrelated to the choices under evaluation. Research with adult populations has identified several pathways by which affect influences decision making (Loewenstein, Weber, Hsee, & Welch, 2001). For instance, the anticipated emotional outcome of a behavioral option—how one expects to feel after making a given choice—contributes to one’s cognitive assessment of its expected value. Indeed, affective states may influence decision processing even when the source of the affect is not directly related to the choices under evaluation. Such incidental affective influences are apparent in experiments demonstrating the effect of preexisting or experimentally elicited affective states on adult perception, memory, judgment, and behavior (Winkielman, Knutson, Paulus, & Trujillo, 2007).

One experiment illustrating this effect found that incidental positive emotion elicited via the presentation of masked happy faces caused participants to pour and drink more of an unfamiliar beverage than participants who had viewed angry faces, despite no differences in self-reported emotion between the two groups (Winkielman, Berridge, & Wilbarger, 2005). Consistent with evidence for extensive overlap in the neural circuitries implicated in the evaluation of socioemotional and choice-related incentive cues (e.g., frontostriatal circuitry, including ventral striatum and ventromedial prefrontal cortex; for a recent review, see Falk, Way, & Jasinska, 2012), Winkielman and his colleagues describe this priming effect as an instance of approach sensitization. That is, neural responses to positively valenced socioemotional stimuli—in this case, responses that do not even reach the level of conscious awareness—may sensitize approach responding to unrelated incentive cues. As we describe below, several characteristics of adolescent neurobehavioral functioning suggest that this approach-sensitization effect could be a particularly powerful influence on adolescent decision making in peer contexts.

Second, relative to adults, adolescents exhibit stronger “bottom-up” affective reactivity in response to socially relevant stimuli. Whereas some controversy remains regarding the degree to which adolescents are more or less sensitive than children and adults to nonsocial reward cues (Galvan, 2010; Spear, 2009), few scholars now dispute that adolescence is a period of peak neurobehavioral sensitivity to social stimuli (Burnett, Sebastian, Kadosh, & Blakemore, 2011; Somerville, 2013). Puberty-related increases in gonadal hormones have been linked to a proliferation of receptors for oxytocin within subcortical and limbic circuits, including the amygdala and striatum (Spear, 2009). Oxytocin neurotransmission has been implicated in a variety of social behaviors, including social bonding and heightened attention to positive social stimuli (Insel & Fernald, 2004). Along with concurrent changes in dopaminergic function within neural circuits broadly implicated in incentive processing (Spear, 2009), these puberty-related increases in gonadal hormones and oxytocin-receptor density contribute to changes in a constellation of social behaviors observed in adolescence.

Peer relations are never more salient than in adolescence. In addition to a puberty-related spike in interest in opposite-sex relationships, adolescents spend more time than children or adults interacting with peers, report the highest degree of happiness in peer contexts, and assign the greatest priority to peer norms for behavior (Brown & Larson, 2009). This developmental peak in affiliation motivation appears to be highly conserved across species: Adolescent rats also spend more time interacting with peers than do younger or older rats, while showing evidence that such interactions are highly rewarding (Doremus-Fitzwater, Varlinskaya, & Spear, 2010). Moreover, several developmental neuroimaging studies have indicated that, relative to children and adults, adolescents show heightened neural activation in response to a variety of social stimuli, such as facial expressions and social feedback (Burnett et al., 2011). For instance, one of the first longitudinal neuroimaging studies of early adolescence demonstrated a significant increase from ages 10 to 13 in ventral striatal and ventral prefrontal reactivity to facial stimuli (Pfeifer et al., 2011). Together, this evidence for hypersensitivity to social stimuli suggests that adolescents may be more likely than adults to experience heightened approach motivation when exposed to positively valenced peer stimuli in decision-making scenarios, thus setting the stage for an exaggerated approach-sensitization effect of peer context on decision making.

Third, adolescents are less capable than adults of “top-down” cognitive control of impulsive behavior. In contrast to social processing, which undergoes relatively sudden changes around the time of puberty, cognitive capacities supporting efficient self-regulation mature in a gradual, linear pattern over the course of adolescence. In parallel with structural brain changes thought to support neural-processing efficiency (e.g., increased axonal myelination), continued gains in response inhibition, planned problem solving, flexible rule use, impulse control, and future orientation occur during adolescence (Steinberg, 2008).

Indeed, evidence is growing for a direct link between structural and functional brain maturation during adolescence and concurrent improvements in cognitive control. In addition to studies correlating white-matter maturation with age-related cognitive improvements (Schmithorst & Yuan, 2010), developmental neuroimaging studies using tasks requiring response inhibition (e.g., go-no/go, Stroop, flanker, and ocular-antisaccade tasks) have demonstrated relatively inefficient recruitment by adolescents of the core neural circuitry supporting cognitive control (e.g., lateral prefrontal and anterior cingulate cortex; Luna, Padmanabhan, & O’Hearn, 2010). Moreover, research on age differences in control-related network dynamics has demonstrated adolescent immaturity in the functional integration of neural signals deriving from specialized cortical and subcortical “hub” regions (Stevens, 2009). This immature capacity for functional integration may contribute to adolescents’ difficulties with simultaneously evaluating social, affective, and cognitive factors relevant to a given decision, particularly when social and emotional considerations are disproportionately salient.

Identification of Mechanisms Underlying Peer Influences on Adolescent Decision Making

In an effort to further delineate the neurodevelopmental vulnerability underlying adolescents’ susceptibility to peer influence, we have conducted a series of behavioral and neuroimaging experiments comparing adolescent and adult decision making in variable social contexts. Specifically, we have sought to determine whether the presence of peers biases adolescents’ decision making by (a) modulating responses to incentive cues, as predicted by the approach-sensitization hypothesis, (b) disrupting inhibitory control, or (c) altering both of these processes.

As a first step in addressing this question, we conducted an experiment in which we randomly assigned late adolescents (ages 18 and 19) to complete a series of tasks either alone or in the presence of two same-age, same-sex peers. Risk-taking propensity was assessed using the Stoplight game, a first-person driving game in which participants must advance through a series of intersections to reach a finish line as quickly as possible to receive a monetary reward (Fig. 1). Each intersection is marked by a stoplight that turns yellow and, sometimes, red as the car approaches, and participants must decide to either hit the brakes (and lose time while waiting for the light to turn green) or run the light (and risk crashing while crossing an intersection). We also administered a go/no-go task as a measure of cognitive control and a delay-discounting task as a measure of preference for immediate over delayed rewards. Whereas no group differences were evident on the go/no-go index of inhibitory control, adolescents in the peer-presence condition took more risks in the Stoplight game (Albert et al., 2009) and indicated stronger preferences for immediate over delayed rewards (O’Brien, Albert, Chein, & Steinberg, 2011) than did adolescents who completed the tasks alone.

Fig. 1. Schematic of the Stoplight game. In this first-person driving game, participants are instructed to attempt to reach the end of a straight track as quickly as possible. At each of 20 intersections, participants must decide to either stop the vehicle (STOP) or take a risk and run the yellow or red light (GO). Stopping results in a short delay. Successful risk taking results in no delay, but unsuccessful risk taking results in a crash and a relatively long delay. Summary indices of risk taking include (a) the proportion of intersections at which the participant decides to run the light and (b) the total number of crashes. ITI = intertrial interval. See original article for figure.

Findings from a recent follow-up experiment suggested that a peer’s observation influences adolescents’ decision making even when the peer is anonymous and not physically present. Using a counterbalanced repeated-measures design, we assessed late adolescents’ performance on a delay-discounting task once in an alone condition and once in a deception condition that elicited the impression that the adolescents’ task performance was being observed by a same-age peer in an adjoining room. As predicted, participants exhibited a stronger preference for immediate rewards in the task when they believed they were being observed than when they were alone (Weigard, Chein, & Steinberg, 2011). Peer observation also increased rates of monetary gambles on a probabilistic gambling task, but only for participants with relatively low self-reported resistance to peer influence (Smith, Chein, & Steinberg, 2011). Along similar lines, Segalowitz et al. (2012) reported that individuals high in self-reported sensation seeking are particularly susceptible to the peer effect on risk taking. Considered together, these behavioral results suggest that the presence of peers increases adolescents’ risk taking by increasing the salience (or subjective value) of immediately available rewards, and that some adolescents are more susceptible to this effect than others.

Our recent work has used brain imaging to more directly examine the neural dynamics underlying adolescent susceptibility to peer influences. In the first of these studies, we scanned adolescents and adults while they played the Stoplight game, again using a counterbalanced within-subjects design (Chein, Albert, O’Brien, Uckert, & Steinberg, 2011). All subjects played the game in the scanner twice—once in an alone condition and once in a peer condition, in which participants were made aware that their performance was being observed on a monitor in a nearby room by two same-age, same-sex peers who had accompanied them to the experiment. As predicted, adolescents, but not adults, took significantly more risks when they were being observed by peers than when they were alone (Fig. 2). Furthermore, analysis of adolescents’ neural activity during the decision-making epoch showed greater activation of brain structures implicated in reward valuation (ventral striatum and orbitofrontal cortex) in the peer-condition scans relative to the alone-condition scans, an effect that was not observed for adults (Fig. 3). Indeed, the degree to which both adolescent and adult participants evinced greater ventral-striatum activation in the peer condition compared with the alone condition was inversely correlated with self-reported resistance to peer influence (Fig. 4). These findings constitute the first evidence that peer presence accentuates risky decision making in adolescence by modulating activity in the brain’s reward-valuation system.

Fig. 2. Susceptibility of adolescents, young adults, and older adults to peer influences on performance in the Stoplight game in Chein, Albert, O’Brien, Uckert, and Steinberg (2011). The graphs show (a) the mean percentage of risky decisions and (b) the number of crashes for participants playing the Stoplight game either alone or with a peer audience. Error bars indicate standard errors of the mean. See original article for figure.

Fig. 3. Brain regions showing an Age × Social Context interaction during the Stoplight game in Chein, Albert, O’Brien, Uckert, and Steinberg (2011). The graphic (a) shows two brain regions exhibiting an Age × Social Context interaction: the right ventral striatum (Montreal Neurological Institute, or MNI, peak coordinates: x = 9, y = 12, z = −8) and the left orbitofrontal cortex (MNI peak coordinates: x = −22, y = 47, z = −10). Brain images are shown by radiological convention (left on right) and thresholded at p < .01 for presentation purposes. The graph (b) shows mean estimated blood-oxygen-level-dependent signal change (standardized coefficients) from the four peak voxels of the ventral striatum and the orbitofrontal cortex in adolescents (adols.), young adults, and adults in alone and peer conditions. Error bars indicate standard errors of the mean. See original article for figure.

Fig. 4. Resistance to peer influence correlated with right-ventral-striatum activity during the Stoplight game in Chein, Albert, O’Brien, Uckert, and Steinberg (2011). Estimated activity was extracted from an average of the four peak voxels in the ventral-striatum region of interest. The graph shows a scatter plot, with best-fitting regression line, of ventral-striatum activity indicating an inverse linear correlation between self-reported resistance to peer influence and the neural peer effect (i.e., the difference in average ventral-striatum activity in peer relative to alone conditions). See original article for figure.

Conclusions and Future Directions

Although our work to date has indicated that the effect of peers on adolescents’ risk taking is mediated by changes in reward processing during adolescence, we recognize that the distinction between risk taking that is attributable to heightened arousal of the brain’s reward system versus that which is due to immaturity of the cognitive-control system is somewhat artificial, given that these brain systems influence each other in a dynamic fashion. Consistent with this notion, in a comparison of children, adolescents, and adults on a task that requires participants to either produce or inhibit a motor response to pictures of calm or happy faces, Somerville, Hare, and Casey (2011) not only found elevated ventral striatal activity for adolescents in response to happy faces, which the authors described as an “appetitive” cue, but also a corresponding increase in failures to inhibit motor responses to the happy (vs. calm) facial stimuli. Thus, adolescents’ exaggerated response to positively valenced social cues was shown to directly undermine their capacity to inhibit approach behavior. Translated to the peer context, this finding suggests that adolescents may not only be particularly sensitive to the reward-sensitizing effects of social stimuli, but that this sensitization may further undermine their capacity to “put the brakes on” impulsive responding.

Despite the promise of this conceptual model, further work is needed to more specifically determine the neurodevelopmental dynamics underlying adolescents’ susceptibility to peer influence and to translate this understanding to the design of effective prevention programs. In an effort to “decompose” the peer effect, we are currently examining age differences in the influence of social cues on neural activity underlying performance on tasks specifically tapping reward processing and response inhibition. In addition, we are investigating whether conditions known to diminish cognitive control (e.g., alcohol intoxication) might exacerbate the influence of peers on risky decision making. Finally, as a first step toward our ultimate goal of using this research to improve the efficacy of risk-taking prevention programs, we are examining whether targeted training designed to promote earlier maturation of cognitive-control skills might attenuate the influence of peers on adolescent decision making.

Link to Article

Introduction

It is widely acknowledged that adolescents, compared to children and adults, are more prone to risky behaviors, including substance use, risky sexual activity, criminal involvement, and reckless driving (Steinberg, 2008). However, early research struggled to pinpoint the specific cognitive immaturity driving this heightened risk-taking. Laboratory studies contrasting adolescent and adult risk processing found minimal differences, suggesting adolescents possess comparable knowledge, values, and processing abilities to evaluate risky decisions (Reyna & Farley, 2006).

This discrepancy between real-world and laboratory findings highlights a crucial factor: the influence of peers. Adolescents rarely make decisions about risk-taking behaviors in isolation. This article explores recent research examining the neurobehavioral underpinnings of adolescent decision-making within peer contexts, suggesting that the presence of peers significantly alters the risk-taking calculus for adolescents.

Peer Influences on Adolescent Risk Behavior

Observational data, coupled with self-reported lower resistance to peer influence among adolescents (Steinberg & Monahan, 2007), strongly implicate peer influence in adolescent risk-taking. For example, adolescent delinquency often occurs in groups, contrasting with the solitary nature of adult offenses (Zimring, 1998). Furthermore, associating with delinquent peers is a strong predictor of delinquent behavior in adolescence, potentially due to peer socialization or shared tendencies towards risk-taking (Bauman & Ennett, 1996; Dishion, Bullock, & Granic, 2002). To disentangle these factors, experimental research directly comparing adolescent and adult behavior in solitary and peer-present decision-making contexts is crucial.

A pioneering study utilizing a computerized driving simulation, the "Chicken Game," demonstrated this peer effect (Gardner & Steinberg, 2005). Early adolescents (age 14), late adolescents (age 19), and adults (age 37) participated, either alone or with same-aged peers observing. While risk-taking was similar across age groups when alone, early adolescents doubled their risky driving with peers present, late adolescents showed a 50% increase, while adults remained unaffected. These findings underscore the need to further investigate the behavioral and neural mechanisms underlying this peer-influenced adolescent risk-taking.

A Neurodevelopmental Model of Peer Influences on Adolescent Decision Making

Building on evidence of significant brain development during adolescence (Albert & Steinberg, 2011; Steinberg, 2008), a neurodevelopmental framework for heightened adolescent susceptibility to peer influence has emerged. This model proposes that, compared to adults, the presence of peers in adolescents triggers a reward-sensitive motivational state, amplifying the immediate rewards of risky choices over long-term benefits of safer options. Three core assumptions of this model are highlighted below.

Firstly, decision-making integrates both cognitive and affective components, even when affect is unrelated to the choices. Research highlights how anticipated emotional outcomes of a choice contribute to its perceived value (Loewenstein, Weber, Hsee, & Welch, 2001). Furthermore, incidental affect, where unrelated emotional states influence decisions, is evident in studies demonstrating how preexisting or induced moods impact adult perception, memory, judgment, and behavior (Winkielman, Knutson, Paulus, & Trujillo, 2007). For instance, subliminal exposure to happy faces led to increased consumption of a novel beverage compared to exposure to angry faces, despite no self-reported mood differences (Winkielman, Berridge, & Wilbarger, 2005). This "approach sensitization" suggests that positive socioemotional stimuli can heighten approach responses towards unrelated rewards, potentially due to shared neural circuitry in socioemotional and reward processing (Falk, Way, & Jasinska, 2012). This effect might be particularly potent in adolescents due to their developing neurobehavioral systems.

Secondly, adolescents, compared to adults, display heightened "bottom-up" affective reactivity to socially relevant stimuli. While debate exists regarding adolescent sensitivity to nonsocial rewards (Galvan, 2010; Spear, 2009), increased sensitivity to social stimuli during adolescence is well-documented (Burnett, Sebastian, Kadosh, & Blakemore, 2011; Somerville, 2013). Puberty-driven hormonal changes increase oxytocin receptors in brain regions like the amygdala and striatum, potentially explaining heightened social behavior and attention to positive social cues (Insel & Fernald, 2004; Spear, 2009). This, combined with changes in dopaminergic function within reward-processing circuits, contributes to altered social behavior in adolescence.

Adolescence represents a peak in affiliation motivation. Alongside heightened interest in romantic relationships, adolescents prioritize peer interaction, report greater happiness in peer contexts, and adhere strongly to peer norms (Brown & Larson, 2009). This is mirrored in animal models, where adolescent rats prioritize and find reward in peer interactions (Doremus-Fitzwater, Varlinskaya, & Spear, 2010). Neuroimaging studies further support this, showing amplified neural responses in adolescents compared to children and adults to social stimuli like facial expressions and feedback (Burnett et al., 2011). For instance, ventral striatal and ventral prefrontal reactivity to faces significantly increases from ages 10 to 13 (Pfeifer et al., 2011). This hypersensitivity to social cues suggests adolescents might experience stronger approach motivation towards positive peer stimuli during decision-making, leading to an exaggerated approach-sensitization effect.

Thirdly, adolescents exhibit less developed "top-down" cognitive control over impulsive behavior compared to adults. Unlike the rapid changes in social processing during puberty, cognitive control develops gradually throughout adolescence (Steinberg, 2008). Brain development, particularly increased axonal myelination, coincides with improvements in response inhibition, planning, impulse control, and future orientation.

Evidence links brain maturation during adolescence to improved cognitive control. Studies correlate white matter development with cognitive enhancements (Schmithorst & Yuan, 2010). Additionally, neuroimaging studies using response-inhibition tasks show adolescents utilize cognitive-control regions like the prefrontal cortex less efficiently than adults (Luna, Padmanabhan, & O'Hearn, 2010). Furthermore, adolescents exhibit immature functional integration of neural signals from specialized brain regions, potentially hindering their ability to simultaneously evaluate social, emotional, and cognitive aspects of decisions, especially when social and emotional factors are salient (Stevens, 2009).

Identification of Mechanisms Underlying Peer Influences on Adolescent Decision Making

To further understand the neurodevelopmental vulnerability underlying peer influence susceptibility, studies comparing adolescent and adult decision-making in different social contexts are crucial. Specifically, do peers influence adolescent decisions by (a) altering responses to reward cues (approach-sensitization), (b) disrupting inhibitory control, or (c) a combination of both?

Initial research examined late adolescents (18-19 years old) randomly assigned to complete tasks alone or with two same-age, same-sex peers observing. Risk-taking was measured using the "Stoplight game," a driving simulation where participants make risk-reward decisions. Inhibitory control was assessed using a go/no-go task, and delay discounting measured preference for immediate versus delayed rewards. While inhibitory control didn't differ between groups, adolescents took more risks in the Stoplight game and showed stronger preference for immediate rewards with peers present (Albert et al., 2009; O'Brien, Albert, Chein, & Steinberg, 2011).

Further research suggests that even an anonymous, physically absent peer can influence adolescent decision-making. Late adolescents completed a delay-discounting task alone and under the (deceptive) impression of being observed by a same-aged peer. As predicted, participants demonstrated a stronger preference for immediate rewards when believing they were observed (Weigard, Chein, & Steinberg, 2011). Similar effects were observed on a probabilistic gambling task, with peer observation increasing risky gambles, particularly in individuals with lower self-reported resistance to peer influence (Smith, Chein, & Steinberg, 2011). Similarly, individuals high in sensation seeking are more susceptible to peer influence on risk-taking (Segalowitz et al., 2012). These findings collectively suggest that peer presence, real or perceived, heightens the salience of immediate rewards for adolescents, increasing their risk-taking, with individual susceptibility varying.

Neuroimaging studies provide further insight. In one study, adolescents and adults underwent brain scans while playing the Stoplight game, once alone and once believing they were observed by same-aged peers (Chein, Albert, O'Brien, Uckert, & Steinberg, 2011). As expected, adolescents, but not adults, took more risks when "observed." Brain imaging revealed that adolescents, compared to adults, showed increased activation in reward-related brain regions (ventral striatum and orbitofrontal cortex) during the peer-observed condition. Notably, the degree of this activation correlated negatively with self-reported resistance to peer influence, supporting the idea that peers amplify the rewarding aspects of risk-taking for adolescents, particularly those more susceptible to peer influence.

Conclusions and Future Directions

While current research points to altered reward processing during adolescence as a key mechanism for peer influence on risk-taking, it's crucial to acknowledge the complex interplay between reward and cognitive-control systems. These systems are dynamically interconnected, and their immature balance in adolescence likely contributes to heightened risk-taking in social contexts.

Further research is crucial to dissect the neurodevelopmental dynamics underlying adolescent susceptibility to peer influence and translate these findings into effective prevention strategies. For instance, directly comparing age-related differences in how social cues influence brain activity during reward processing and response inhibition tasks can provide valuable insights. Additionally, examining whether factors that compromise cognitive control, such as alcohol intoxication, exacerbate peer influence on adolescent risk-taking is crucial.

Ultimately, applying these research findings to real-world interventions is paramount. Investigating whether targeted training programs aimed at enhancing cognitive control can mitigate peer influence on adolescent decision-making is a promising avenue for future research. Such efforts hold the potential to equip adolescents with the necessary skills to navigate social pressures and make healthier, safer choices.

Link to Article

Introduction

It’s no secret that adolescents are more prone to risky behaviors compared to children or adults. This is evident in their higher rates of experimenting with things like alcohol, drugs, unsafe sex, criminal activities, and reckless driving. Early research attempting to pinpoint the specific cognitive immaturity driving this heightened risk-taking tendency didn't yield much. Numerous controlled lab experiments, comparing adolescents and adults' abilities to understand and process risk information, actually found that adolescents possess the knowledge, values, and cognitive efficiency to evaluate risky choices as well as adults.

So, why do adolescents seem so risk-averse in the lab but so risk-prone in real life? The answer might lie in the social context. As one teenager put it, "If I’m by myself and I didn’t know anybody, then I wouldn’t do it. That’s no fun." Basically, if adolescents made all their decisions about things like drinking, driving, relationships, and rule-breaking in the sterile environment of a lab, their choices would likely be as cautious as any adult's. But here's the catch: teenagers spend a significant amount of time with other teenagers. This article explores new research on the brain mechanisms behind adolescent decision-making in peer groups, suggesting that being around other teenagers fundamentally changes how adolescents calculate risk.

The Influence of Peers on Teen Risk-Taking

Research consistently shows that adolescents are more susceptible to peer pressure than adults. Observational data also highlights peer influence as a major factor contributing to risky decision-making in teenagers. For example, crime statistics reveal that teens typically commit delinquent acts in groups, unlike adults who are more likely to offend alone. Furthermore, one of the strongest predictors of delinquent behavior in adolescence is associating with delinquent peers. This link is attributed partly to peer socialization, such as learning deviant behaviors from each other, and partly to friendship selection, where risk-taking teens naturally gravitate towards one another. Since it's tricky to separate these factors using correlational data alone, our research team has been conducting experiments directly comparing how adolescents and adults behave when making decisions alone versus with peers.

In the first study of its kind to examine age differences in peer influence on risky decision-making, we tested early adolescents (average age 14), late adolescents (average age 19), and adults (average age 37) using a computer driving simulation called the "Chicken Game." In this game, players are challenged to drive as far as possible on a course while avoiding a wall that could appear unexpectedly. We manipulated peer context by randomly assigning participants to play either alone or with two same-aged peers present. When playing alone, all three age groups showed similar levels of risk-taking. However, early adolescents took twice as many risks with peers present compared to when alone. Late adolescents' driving became about 50% riskier with peers, while adults showed no difference in risk-taking based on social context. Our research program continues to investigate and define the behavioral and neural mechanisms behind this peer effect on adolescent risk-taking.

A Brain-Based Model of Peer Influence on Teen Decision-Making

Building on extensive research showing significant brain development throughout adolescence and beyond, we've developed a neuroscientific explanation for why teenagers are more vulnerable to peer influence. We propose that being around peers, more so in adolescents than adults, triggers a reward-sensitive state in the brain. This amplifies the perceived value of immediate rewards, making teens favor the short-term benefits of risky choices over the long-term value of safer options. While a complete review of the evidence supporting this theory is beyond this article's scope, let's break down three key assumptions of this model.

Firstly, decisions are influenced by both logic and emotions, even when emotions aren’t directly related to the choices at hand. Studies with adults have shown several ways emotions influence decision-making. For example, how we expect to feel after making a choice contributes to our overall assessment of that choice's value. In fact, our emotional states can even affect decision-making when the source of the emotion is totally unrelated to the choices we're considering. These "incidental" emotional influences are evident in studies demonstrating how pre-existing or experimentally induced moods affect adult perception, memory, judgment, and behavior.

One experiment demonstrating this effect involved showing participants masked happy or angry faces. Despite not consciously registering the emotions on the faces, those who saw happy faces poured and drank more of an unfamiliar beverage compared to those who saw angry faces. This suggests that even subconscious positive emotions can make individuals more receptive to unrelated pleasurable experiences. Winkielman and colleagues call this a priming effect due to approach sensitization. Essentially, positive social and emotional stimuli, even those we don't consciously process, can make our brains more sensitive to rewards in general. Several aspects of how adolescents' brains work suggest that this approach-sensitization effect could be particularly strong on their decision-making when they're with peers.

Secondly, adolescents are more reactive to social stimuli than adults, meaning their emotions are more easily swayed by social interactions. While there's debate about whether teens are more or less sensitive than children and adults to non-social rewards, most researchers agree that adolescence is a peak time for sensitivity to social cues. Puberty hormones trigger an increase in oxytocin receptors in brain regions involved in emotional and social processing, like the amygdala and striatum. Oxytocin is linked to social bonding and increased attention to positive social interactions. Combined with changes in dopamine function in reward pathways, these hormonal shifts contribute to changes in social behavior during adolescence.

Peer relationships are paramount during the teenage years. Aside from a surge in interest in romantic relationships, teens spend more time with peers than children or adults, report greater happiness in peer settings, and place a higher value on peer norms. This developmental peak in the need for belonging appears across species. For instance, adolescent rats also prioritize socializing with peers, finding it highly rewarding. Furthermore, brain imaging studies show that teens display greater activity in brain areas associated with social processing, like the ventral striatum and prefrontal cortex, when responding to social stimuli compared to children and adults. One longitudinal study showed a significant increase in these regions' activity in response to facial expressions between the ages of 10 and 13. This heightened sensitivity to social information suggests that adolescents are more likely than adults to experience stronger feelings of reward and motivation when exposed to positive peer interactions, making them more susceptible to the influence of peers on their choices.

Thirdly, teenagers haven’t fully developed the ability to control impulsive behavior compared to adults. While social processing undergoes rapid changes during puberty, cognitive abilities related to self-control develop more gradually throughout adolescence. This lines up with brain development; as neural connections become more efficient (like increased myelin), adolescents gradually improve in their ability to inhibit responses, plan, be flexible, control impulses, and think about future consequences.

Evidence increasingly links brain maturation during adolescence to improvements in cognitive control. Studies have correlated the development of white matter in the brain with age-related improvements in cognitive abilities. Furthermore, brain imaging studies using tasks that require response inhibition (like the go/no-go task) have shown that adolescents are less efficient at activating brain regions responsible for cognitive control, such as the prefrontal cortex. Additionally, research on the communication between different brain regions suggests that the integration of signals between key areas involved in control is less mature in adolescents. This immaturity might make it harder for them to juggle social, emotional, and logical factors when making decisions, particularly when social and emotional considerations are more prominent.

Unraveling the Mechanisms of Peer Influence

To better understand how adolescent brains make them vulnerable to peer pressure, our research team has conducted studies comparing adolescent and adult decision-making in different social situations. Specifically, we want to know if the presence of peers influences teenagers' decisions by: a) changing how their brains respond to rewarding cues (the approach-sensitization hypothesis), b) disrupting their ability to control impulses, or c) a combination of both.

Our initial experiment involved randomly assigning late adolescents (ages 18-19) to complete tasks either alone or with two same-aged, same-sex peers present. We measured risk-taking using the "Stoplight game," a driving simulation where participants have to reach a finish line as quickly as possible to earn a reward. At intersections, players decide to either brake for a yellow or red light (losing time) or run the light (risking a crash and longer delay). We also assessed their cognitive control with a go/no-go task and their preference for immediate versus delayed rewards using a delay-discounting task.

While there were no differences in inhibitory control on the go/no-go task, adolescents in the peer group took more risks in the Stoplight game and showed a stronger preference for immediate rewards compared to those who completed the tasks alone.

Interestingly, a follow-up experiment suggested that even the perception of being observed by a peer can influence adolescents' decisions. We had late adolescents complete a delay-discounting task, once alone and once while being led to believe a peer in another room was observing their performance. As predicted, participants were more impulsive and chose immediate rewards more often when they thought they were being watched. Similarly, perceived peer observation led to riskier gambling behavior, but only in those who reported being easily influenced by peers. Segalowitz et al. (2012) also found that individuals who enjoy thrill-seeking are particularly susceptible to this peer effect on risk-taking. These findings indicate that the presence (or perceived presence) of peers increases adolescent risk-taking by enhancing the perceived value of immediate rewards, and this effect varies between individuals.

To look directly at what happens in the brain, we conducted brain imaging studies while adolescents and adults played the Stoplight game, again alone and with the belief that same-aged peers were observing them. As expected, adolescents took significantly more risks with a perceived peer audience, while adults did not. Brain imaging revealed greater activity in adolescents' reward centers (ventral striatum and orbitofrontal cortex) when they thought peers were watching. This difference was not observed in adults. Furthermore, across both age groups, the extent to which the ventral striatum was more active in the peer condition correlated with how susceptible individuals reported being to peer pressure. These results provide the first neural evidence that peer presence increases risk-taking in adolescents by influencing activity in the brain's reward system.

Looking Ahead: Implications and Future Research

Our research shows that peers' influence on adolescent risk-taking is related to changes in how their brains process rewards. However, we recognize that the interplay between heightened reward sensitivity and immature impulse control is complex, as these systems constantly interact. Supporting this idea, a study by Somerville, Hare, and Casey (2011) compared children, adolescents, and adults on a task where they had to either respond or inhibit responses to images of calm or happy faces. They found that adolescents not only showed greater activity in the ventral striatum (a reward center) in response to happy faces but also made more errors inhibiting their responses to these positive social cues. This suggests that not only are teens more sensitive to positive social cues, but this sensitivity might hinder their ability to control impulsive actions. In the context of peer influence, this means adolescents may be more drawn to the rewarding feeling of fitting in with peers, and this feeling may further weaken their ability to resist impulsive actions.

While our model shows promise, more research is needed to fully understand the brain's development concerning peer influence and how to translate these findings into effective prevention programs. Currently, we are investigating how social cues specifically affect reward processing and impulse control across different ages. Additionally, we are exploring whether factors known to reduce cognitive control, like alcohol intoxication, might magnify the influence of peers on risky behaviors. Ultimately, our goal is to use this research to improve interventions for risky behavior in youth. As a first step, we are examining whether training programs that specifically target and strengthen cognitive control skills can help adolescents resist negative peer pressure.

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Why Taking Risks Is More Fun With Friends

"It seems like people accept you more if you’re, like, a dangerous driver or something. If there is a line of cars going down the road and the other lane is clear and you pass eight cars at once, everybody likes that. . . . If my friends are with me in the car, or if there are a lot of people in the line, I would do it, but if I’m by myself and I didn’t know anybody, then I wouldn’t do it. That’s no fun."

—Anonymous teenager, as quoted in The Culture of Adolescent Risk-Taking

It's a well-known fact that teenagers are more likely to take risks compared to kids or adults. This is obvious from the higher rates of dangerous behaviors like drinking, smoking, drug use, unprotected sex, criminal activity, and reckless driving. Early research tried to figure out what was different about teenagers' brains that made them more likely to take risks, but they didn't find many answers. Lots of lab experiments compared how well teens and adults could understand and process information about risks, but they discovered that teens actually have the knowledge, values, and mental skills to make decisions about risks just as well as adults can.

So, if teens are so risky in the real world, why do they seem so cautious in the lab? We believe the answer is clear in the words of the teenager quoted above: "If I’m by myself and I didn’t know anybody, then I wouldn’t do it. That’s no fun.” If teenagers made all their decisions about drinking, driving, relationships, and breaking rules in a boring lab by themselves, they'd probably be just as careful as adults. But here's the catch: teenagers spend a huge chunk of their time with other teenagers.This article explores new research on how teenagers' brains work when they make decisions around their friends. This research suggests that hanging out with other teens totally changes how teenagers think about risks.

Friends' Influence on Risky Behavior

Teens say they're less able to resist peer pressure than adults, and we can see this in real life too. For example, crime statistics show that teens usually commit crimes in groups, while adults are more likely to act alone. One of the biggest signs that a teenager might get involved in criminal activity is if their friends are already doing it. This could be because teens learn bad behavior from each other, or because teens who like taking risks naturally become friends. It's hard to know for sure just by looking at who hangs out with who, so our lab decided to do experiments directly comparing how teens and adults act when they're alone versus with their friends.

One of the first experiments to look at this had young teens (around 14 years old), older teens (around 19), and adults (around 37) play a computer driving game called the Chicken Game. In the game, a person has to drive as far as they can on a track without hitting a wall that can pop up anytime. To see the effect of friends, some people played alone, and some played with two people their own age watching. When they played alone, all the age groups took similar risks. But, young teens took twice as many risks with friends watching! Older teens took about 50% more risks with friends around, and adults didn't change how they played at all. Our research team is now trying to figure out exactly how being around friends affects teens' risky decisions.

How The Brain Develops and Why Friends Matter

We know that the brain changes a lot during the teenage years (and even after!). We've used this to develop a theory about why teenagers are more easily influenced by their peers. Here's the idea: being around friends can trigger a "reward-sensitive" state in teenagers' brains more than in adults' brains. This basically means that being with friends makes rewards seem even better and more immediate, leading teens to choose the short-term thrill of a risky choice over playing it safe. We don't have space to explain all the scientific evidence here, but we can offer three key ideas behind this theory.

1. Emotions affect decisions, even when if we don't realize it. Research on adults shows that our emotions influence our choices in several ways. For example, if a person thinks a decision will make them feel good, they're more likely to see it as a good choice. Emotions can even affect our choices when they're not directly related to what we're deciding. Scientists call this incidental emotional influence, and it can be seen in experiments where people's mood affects how they see things, remember information, make judgments, and behave.

Here's one example: in one study, people who saw quick flashes of happy faces (so fast they didn't even know they saw them!) poured and drank more of a strange drink than people who saw angry faces, even though they didn't report feeling any different. This happens because the parts of the brain that process social and emotional information overlap with the parts that make decisions. Positive social experiences can make a person more likely to go for other rewards, too, even if they're unrelated.

Since teenagers' brains are even more sensitive to social stuff than adults' brains, this effect is probably stronger for them.

2. Teens' brains are wired to respond strongly to social stuff. While there's debate about whether teenagers are more or less sensitive to rewards in general, almost everyone agrees: teenage brains are highly tuned to social information). The hormonal changes during puberty flood the brain with chemicals like oxytocin, which makes one crave social connection and pay extra attention to positive social cues. These changes, along with how dopamine works in the brain during adolescence, contribute to teenagers' intense focus on social life.

It's no surprise then that relationships become super important during the teenage years. Along with a surge of interest in dating, teenagers spend more time with friends, feel happier with friends, and care more about fitting in with their peers than they did as children or will as adults. Even teenage rats spend more time socializing and seem to really enjoy it. Brain imaging studies show that teenagers' brains light up more strongly than children's or adults' brains when they see social cues like facial expressions or get feedback from others. For example, one study found that the reward centers of the brain became much more active in response to pictures of faces between the ages of 10 and 13. This all points to the idea that teenagers' brains are primed to experience social situations as super rewarding, which could explain why their friends have such a big impact on their decisions.

3. Teenagers are still learning to resist impulses. While the brain goes through a lot of social and emotional development during puberty, the parts of the brain that help control oneself mature more slowly and steadily throughout adolescence. As the brain develops (especially the connections between brain cells), a person gets better at things like resisting impulses, planning ahead, being flexible, and thinking about the future.

Research is showing a clear link between these brain changes and improvements in self-control. Studies have found that teens' brains don't use the control centers (like the prefrontal cortex and anterior cingulate cortex) as efficiently as adults' brains when they need to resist impulses. This means teenagers might have a harder time thinking clearly and making good choices when their emotions are running high, especially in social situations.

Figuring Out How Friends Influence Teens' Choices

Our research team has been doing more experiments to try to pinpoint how social pressure affects teenagers' decisions. We're trying to find out if having friends around:

a) makes rewards seem more appealing, b) makes it harder to resist impulses, or c) does both of these things.

To figure this out, we had a group of older teens (18-19 years old) complete some tasks either alone or with two people their own age and gender watching them. First, we measured their risk-taking by having them play a driving game called the Stoplight game. In this game, a person has to drive through a bunch of intersections to reach the finish line as fast as they can to win money. At each intersection, the light turns yellow, and sometimes red. This person has to decide whether to slam on the brakes (and waste time waiting) or run the light (and risk crashing).

We also had them do a go/no-go task (to measure impulse control) and a delay-discounting task (to see how much they preferred immediate rewards over waiting for bigger ones). The results were interesting! The teens who played the driving game with their friends watching took way more risks and were more impatient for rewards than those who played alone. However, there was no difference between the groups on the impulse control task.

We did another experiment to see if teens would act differently even if their friend was anonymous and not in the room. We tricked some teens into thinking another teen in a different room was watching them play a game. Guess what? Just thinking someone was watching made them choose the immediate rewards more often. In another experiment, we found that teens who said they're easily influenced by peers were more likely to take risks in a gambling game when they thought someone their age was watching. Similarly, another study found that "thrill-seeking" people are especially susceptible to peer pressure when making risky decisions. These findings suggest that even the idea of a friend watching is enough to make some teens more impulsive, especially if they're already sensitive to peer influence.

Recently, we used brain imaging to get an even closer look at what happens in teens' brains when they're under social pressure. We had teens and adults play the Stoplight game while inside a brain scanner. They played twice: once alone and once while we made them think two other people their age and gender were watching them on a monitor in another room. Just like in the previous experiment, the teenagers took way more risks when they thought their friends were watching, while the adults didn't change their behavior.

When we looked at the brain scans, it got even more interesting! The teenagers' brains showed more activity in the reward centers (like the ventral striatum and orbitofrontal cortex) when they were playing with an audience compared to when they were alone. This didn't happen in the adults' brains.

Even cooler, we found that the more active these reward centers were when teens thought they had an audience, the more likely they were to say they're easily influenced by their friends.

This was the first evidence that peer pressure actually changes how rewarding teenagers find risky decisions!

What Does It All Mean? What's Next?

So far, our research shows that teens are more likely to take risks around friends because their brains are wired to find social rewards extra exciting. But it's not quite as simple as that. The line between taking more risks because a teen is more sensitive to rewards and taking more risks because they're bad at controlling themselves is blurry. These two brain systems are constantly talking to each other!

One study showed this perfectly: when researchers compared children, teens, and adults on a task where they had to either press a button or stop themselves from pressing a button when they saw pictures of faces, they found that teenagers not only showed more activity in the reward centers of their brains when they saw happy faces but were also more likely to accidentally press the button when they weren't supposed to. This means that the excitement of seeing a happy face actually made it harder for them to control their impulses. So, not only are teenagers' brains super sensitive to the excitement of social rewards, but that excitement might also make it even harder for them to think clearly and make safe choices.

There's still a lot to learn. We're currently working on figuring out exactly when during adolescence these brain changes happen and how they work together to make teens vulnerable to peer pressure. We're also exploring whether things that impair judgment, like alcohol, might make the peer effect even stronger. Ultimately, we want to use all this research to help design better programs to prevent risky behavior in teenagers. For example, we're looking at whether teaching teenagers how to control their impulses better can help them resist peer pressure and make safer choices.

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Introduction

We all know that teenagers are more likely to do risky things than kids or grown-ups. This includes things like trying cigarettes or alcohol, having sex without protection, getting into trouble, and driving recklessly. Scientists wanted to understand why, so they studied how teenagers think about risk. Surprisingly, when they asked teenagers to make decisions about risky things in a lab, by themselves, they were just as careful as adults. So why do teenagers take more risks in real life?

Well, think about this: teenagers spend a lot of time with their friends. When they're with their friends, they might make different decisions than they would if they were alone. Let's look at why that might be.

How Friends Influence Teenagers' Risky Choices

While being around friends doesn't make adults make riskier decisions, it does for teenagers. Scientists wanted to know why.

They did an experiment where they asked teenagers and adults to play a driving game. In the game, players had to decide whether to stop at yellow lights or speed through them and risk crashing. Some people played alone, and some played while their friends were watching. When their friends were watching, teenagers took way more risks than when they were alone. Adults, on the other hand, didn't change how they played the game, even when they knew someone was watching. This tells us that teenagers are more likely to be influenced by their friends, especially when it comes to risky decisions.

What Happens in Teenagers' Brains When They're With Friends?

Scientists believe that changes in teenagers' brains might explain why they're more easily influenced by their friends.

• Teenagers' brains are wired to enjoy rewards. When teenagers are with their friends, their brains release chemicals that make them feel good. This feeling of reward can make them want to take more risks, because risky behavior can be exciting and lead to more rewards (like the thrill of driving fast).

• Teenagers' brains are still developing self-control. The part of the brain that helps us resist impulses and think about long-term consequences isn't fully developed until our mid-twenties. This means that teenagers may have a harder time saying "no" to risky behavior, especially when they're with friends and feeling the excitement of potential rewards.

• Social rewards are extra powerful for teenagers. During the teenage years, our brains become really good at understanding and responding to social cues. This means that teenagers are more sensitive to things like peer pressure and social acceptance. They really want to fit in and impress their friends, which can lead them to make riskier choices.

What Does This Mean?

Even though teenagers' brains are still developing, it doesn't mean they can't make good choices. Understanding how their brains work can help them make smarter and safer decisions. It's also important for adults to talk to teenagers about the risks associated with certain behaviors and to help them develop strategies for resisting peer pressure.

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