This includes individuals who are sensitive to reward prediction errors , those who have a preference for immediate rather than delayed rewards , who are impulsive , and adolescents . Adolescence can be considered an intersection in development where opportunities to engage in risky behavior, such as substance use, is met with a heightened sensitivity to reward, suggesting this population may be particularly vulnerable to addiction . Because opportunities to engage in substance use often occur in social settings and are promoted by social cues , a full understanding reward prediction error should arguably consider the context in which it occurs in addition to the dopaminergic response.While prediction error is traditionally viewed as a learning signal, calculated by determining the difference between an expectation and its associated outcome, the present studies aim to assess violations of expectations, as they are more inclusive of the prediction error calculation and the context in which they occur. Violations of expectations are couched in Expectancy Violations Theory, which is inclusive of social rules in communication and behavioral interactions between people . Research on this theory has demonstrated that people have unspoken expectations in relationships, and violating them can alter the relationship . Additionally,weed drying room different cognitive and affective processes result from experiencing expectancy violations. Upon reading incongruent statements compared to congruent statements , adults demonstrate increased event-related potential amplitude.
When participants read negatively valenced incongruent semantic statements they showed negative affect compared to when the statements were positive , suggesting people are sensitive to incongruences of their expectations. Functional Magnetic Resonance Imaging studies have reported similarities between activation in regions implicated in prediction error and expectancy violations, such that positive expectancy violations result in activation of striatal regions , whereas negative expectancy violations result in activation of frontal regions . The aforementioned studies on the effects of expectancy violations focus on semantic incongruences; but importantly, additional neural activation is implicated in social incongruences. Researchers have found that upon realization of a social expectancy violation, participants show increased activation in regions associated with recognition of expectation inconsistency, including the posterior medial frontal cortex . Social neuroscience research has explored responses to violations of expectations from relationship partners , whereby participants learned how favorably or unfavorably their significant other felt about them. This study demonstrated activation in regions associated with socioemotional decision-making, motivation, and reward, including the ventral medial prefrontal cortex, ventral tegmental area, and the ventral striatum. People also tend to recruit cognitive control regions, such as the dorsolateral prefrontal cortex when they learn their beliefs are inconsistent with a group’s beliefs . In a study by Klucharev and colleagues, participants rated images of women. When they were prompted with their rating followed by a group’s collective rating, participants changed their responses to match the group .
Recognizing these differences in expectations leads to social conformity, whereby a person realizes their expectation deviates from an outcome, and makes an effort to change their opinion to match the group’s opinion . When people recognize a discrepancy between their beliefs and someone else’s, error detection and eagerness to reduce error is present in brain activation . People are typically inclined to modify their opinions and behaviors to conform to a group’s beliefs when they realize their beliefs differ from the group’s . Researchers examining individual differences in responses to positive violations of expectations have found that individuals with traits that are characteristic of adolescents, such as sensation seeking, novelty seeking , and impulsivity demonstrate an increased neural response to an unexpected outcome. Exploring the effects of social violations of expectations in an adolescent population is important because teenagers are particularly sensitive to social feedback and are more reactive in socioemotional contexts compared to other age groups. Notably, adolescents are also susceptible to peer influence , suggesting these phenomena should be explored in concert.Adolescents demonstrate a diminished ability to distinguish between different levels of positive social feedback—finding all positive social feedback rewarding , and are especially afflicted when they have been ostracized by their peers , demonstrating a heightened sensitivity to both positive and negative social feedback. In the laboratory, researchers have found adolescents take more risks when they are in the presence of their peers compared to when they are alone , and demonstrate increased neural activation in reward sensitive brain regions compared to adults when making risky decisions in the presence of their peers . Reports indicate that adolescents partake in many real-world risky activities such as speeding while driving, binge drinking, and using and abusing illicit drugs .
Additionally, they demonstrate delinquent behaviors perhaps in an effort to achieve the sensation of reward—though the outcome of these activities can have dangerous and sometimes fatal consequences. Adolescents are more reactive in affective contexts than adults, demonstrating increased mesolimbic neural activation and impaired decision-making in the “heat of the moment” . A potential reason for this may be due to an imbalance that exists between the cognitive control and emotional arousal systems during adolescence . While reward circuitry is recruited for emotional and rewarding experiences, the prefrontal cortex, which is associated with cognitive control and is known to aid in emotion regulation, does not fully mature until adulthood and is less functionally mature in adolescence by comparison . Many fMRI studies illustrate decreased engagement signal of these areas in adolescents compared to adults when performing the same tasks requiring cognitive control ; while others suggest enhanced activation relative to adults . Protracted development of the prefrontal structures and increased engagement of subcortical structures have been implicated in reward and sensation-seeking behaviors during adolescence. Because adolescents spend more time with peers than other age groups , understanding their behavior following an emotional event is critical in determining how adolescents behave and respond neurobiologically when their peers violate their expectations. While adolescence marks a time of sensitivity to peer feedback, it is plausible that some individuals are more sensitive than others, and are thus more susceptible to peer influence than others—making a more concerted effort to be well received and accepted by their peers. Several vulnerability factors have been implicated in characterizing individuals who are more susceptible to peer influence, including those who have low self-esteem are sensitive to rejection ,drying rack for weed and/or are victims of bullying . Notably, not all peer influence is explicit—in fact, adolescents report choosing to partake in risky behaviors in an effort to be more well-liked or accepted by their friends and higher status peers, more than they report feeling coerced . This suggests adolescents are primarily motivated to mirror their peers’ behaviors to achieve the sensation of reward . Additionally, research has shown that compared to individuals who are more susceptible to peer influence, individuals who report increased resistance to peer influence demonstrate greater recruitment of cognitive control regions in emotional contexts . This suggests that perhaps individuals who are more likely to succumb to peer influence demonstrate a lesser engagement of cognitive control regions to regulate their emotions, and are particularly sensitive to social feedback.
These individual differences associated with peer influence are essential to consider because individuals who are more sensitive to social feedback may also demonstrate greater emotional and behavioral reactivity when that feedback is unexpected.The goal of this dissertation was to implement novel, ecologically valid experimental designs to determine whether neural responses to social feedback were associated with real world behaviors in adolescents. Implementing an ecologically valid task is meaningful, as previous research has demonstrated individuals are sensitive to feedback in computer-like games from unknown peers—suggesting that actual evaluative feedback from a close friend may elicit a more robust or different neural response, and may also be more closely aligned with an individual’s real-world behaviors. As previously mentioned, violations of expectations occur in both humans and non-human primates, suggesting that across species, it is a critical signal for learning. Importantly, while many studies have examined this phenomenon in adults, few have examined violations of expectations in adolescents . Because adolescence is marked by an increase in sensitivity and responsivity to social feedback and reward, examining social violations of expectations in this age group may elucidate whether there are differential neural and behavioral responses that are specific to social feedback. Additionally, by examining behaviors that are known to be associated with reward in adolescence, we can determine whether neural responses to social feedback may be associated with behaviors that occur in social settings . The following chapters present new task designs and evidence to use for future research to predict which adolescents will be most likely to use substances and become susceptible to peer influence.The goal of the first study was to examine the neural mechanisms in adolescents associated with learning social information from a friend by using a novel social violations of expectations task. We hypothesized that adolescents would report feeling happier and demonstrate activation in dopaminergic rich brain regions, such as the ventral striatum when their expectations were positively violated compared to negatively violated, where they would report feeling less happy by comparison and demonstrate increased activation in regions associated with pain and rejection, such as the insula and subgenual anterior cingulate cortex , respectively. We found greater VS activation for positive social violations and greater insula and subACC activation for negative social violations. Participants reported feeling happiest when expectations were met compared to when expectations were positively or negatively violated. This study suggests that while learning unexpected positive information compared to negative information may be preferred, learning unexpected social information during adolescence could be disruptive to the cognitive harmony that a teenager has regarding his/her friendship, which may have implications for adolescent behavior in affective contexts. The second study sought to understand whether neural responses to social violations of expectations evinced in Study 1 were associated with self-reported substance use. We hypothesized that adolescents who demonstrated an increase in ventral striatal response when expectations were positively violated would have a greater affinity for reward and use more substances than adolescents who demonstrated a decreased ventral striatal response when experiencing a positive violation of expectations. We found adolescents reported using socially acceptable substances more than less socially acceptable substances; and those who demonstrated increased VS response for violations of expectations used more socially acceptable substances than adolescents who demonstrated decreased VS response by comparison. We conclude that adolescents who feel rewarded when they receive new social information from a friend are socially more likely to act in ways to reinforce a rewarding sensation when they are with their friends, including engaging in socially acceptable substance use.In the third study, we assessed whether ventral striatal response to violations of expectations in Study 1 and self-reported substance use in Study 2 was associated with self reported and experimentally manipulated susceptibility to peer influence. We hypothesized that self-reported susceptibility to peer influence would be associated with experimentally manipulated peer influence. We also hypothesized that adolescents would be more susceptible to peer influence if they demonstrated an increase VS response to violations of expectations and reported using substances. We found that participants who reported a greater susceptibility to peer influence reported a greater likelihood to use socially acceptable substances following the peer influence manipulation. We also found participants who demonstrated increased VS activation for violations of expectations reported sharing their opinions with their peers. This study concludes that adolescents who are more susceptible to peer influence are more considerate of their peers’ perspectives and have a greater motivation to modify their social behaviors to be accepted. Adolescence is a pivotal time to learn social information from peers, who provide insight about the dynamic social landscape. Adolescents show an increased desire for positive peer feedback compared to other age groups , and are more likely than adults to change their behavior in the presence of their peers . Neuroimaging research suggests that the observed hypersensitive response in mesolimbic circuitry to emotional and rewarding stimuli, coupled with the protracted development of cognitive control circuitry in the brain may explain enhanced sensitivity to social information evinced during adolescence . Extensive research on prediction error , has demonstrated that accurate predictions in daily life are beneficial and adaptive . Organisms can only learn about the environment by evaluating whether our expectations of what we think is true or what we think will happen are violated or not.