Neurobiological Sensitivity to Social Rewards and Punishments Moderates Link Between Peer Norms and Adolescent Risk Taking

Socioeconomic status and adolescents' risk-taking behavior: No longitudinal link or differences by neurobiological activation when anticipating social rewards

This longitudinal, preregistered study investigated the hypothesis that adolescents who are raised in socioeconomic adversity engage in relatively more health-compromising risk-taking behavior during years when they show relatively heightened anticipation to social rewards. We operationalized this on a neurobiological level as activity of the ventral striatum, a region of the brain that is involved in social reward processing. A sample of 170 racially and socioeconomically diverse adolescents (12years at Wave 1, 53 % women, 35 % Latine, 29 % White, 22 % Black) completed annual assessments for up to five years, yielding 478 total observations. During annual fMRI scans, adolescents completed a Social Incentive Delay task during which we measured activation of the ventral striatum in response to anticipating social rewards relative to social punishments. Adolescents also self-reported risk-taking behavior annually, and we linked measures of baseline socioeconomic status via parent report and neighborhood census data. Our preregistered hypotheses were not supported; baseline socioeconomic status was not associated significantly with risk-taking behavior, even during years when adolescents were more attuned to social rewards. Sensitivity analyses examined the role of the anterior insula and amygdala and also yielded null results. Adolescents' risk-taking behavior may not be as closely linked to socioeconomic status or social reward activation as previously hypothesized.

Does cognitive control mediate the relationship between peer presence and adolescent risk-taking? An ERP study

Peer presence influences risk-taking behavior, particularly in adolescence. Based on the dual system model, this event-related potential study examined whether and how the presence of a peer displayed a preference for risky behavior would increase adolescents' risk-taking by disrupting their cognitive control processes in either emotional or non-emotional contexts. A sample of 106 adolescents (17-19 years of age) completed two Stoop tasks and a Balloon Analog Risk Task under three peer presence conditions. Results revealed that compared to other conditions, the presence of a risk-averse peer caused adolescents to make safer decisions through improving their conflict monitoring (more negative N200-diff), whereas a risk-preference peer's presence led adolescents to more risky decisions through disrupting their conflict resolution (more positive N450-diff) but they were only observed on the Emotional Stroop task. These findings suggest that different peer presence contexts could increase or decrease adolescents' risk-taking behaviors by influencing their cognitive control under an emotional context rather than in a non-emotional context.

Wanting to matter and learning to care: A neurodevelopmental window of opportunity for (Pro) social learning?

Wanting to matter-to feel socially recognized, appreciated, and capable of actions that benefit others-represents a fundamental motivation in human development. The motivational salience of mattering appears to increase in adolescence. Evidence suggests this is related to pubertal increases in the incentive salience for gaining social value and personal agency. This can provide a useful heuristic for understanding motivational proclivities (i.e. wanting to matter) that influence action-outcome learning as young adolescents are exploring and learning how to navigate increasingly complex social and relational environments. Adolescence also brings new capacities, motives, and opportunities for learning to care about and contribute to the benefit of others. Together, these create a window of opportunity: a sensitive period for learning to gain salient feelings of mattering through caring prosocial actions and valued societal contributions. Successfully discovering ways of mattering by doing things that matter to others may contribute to formative socio-emotional learning about self/other. Advances in understanding these social and relational learning processes and their neurodevelopmental underpinnings can inform strategies to improve developmental trajectories of social competence and wellbeing among adolescents growing up in a rapidly changing and increasingly techno-centric world.

Digital social multitasking (DSMT) and digital stress among adolescents: A peer norm perspective

Background

Digital stress refers to the stress resulting from persistent use of digital media. Given its major implications for well-being, it is crucial to explore how the use of digital media would contribute to the stress. Drawing on the frameworks of DSMT (i.e., using a digital device during social interactions) and perceived peer norms, we explored whether and how perceived peer norms of DSMT and adolescents' own DSMT were associated with digital stress.

Method

Adolescents between the ages of 12 and 18 were recruited through the Qualtrics survey panels. A total of 2105 adolescents completed a one-time online survey (Mage = 15.39, S.D. = 1.82).

Results

Path analysis revealed that all three self-DSMT variables (level, positive self-perception, negative self-perception) were associated with higher digital stress, with level and negative self-perception having stronger associations than did positive self-perception. Furthermore, peer DSMT level was related to higher digital stress both directly and indirectly through all three self-DSMT variables. Positive peer perception of DSMT was indirectly related to higher digital stress through higher self-DSMT level and more positive self-perception of DSMT, but was related to lower digital stress through reduced negative self-perception of DSMT. Negative peer perception of DSMT contributed to higher digital stress both directly and indirectly by intensifying teens' own negative perception of DSMT. Judging from the total-paths coefficients, all three peer norm variables were related to higher digital stress, with level having the largest coefficient, followed by negative peer perception and finally positive peer perception of DSMT.

Discussion and conclusion

All three perceived peer norms of DSMT (level, positive perception, negative perception) had the potential to increase digital stress directly and/or via impacting teens' own engagement in and perceptions of DSMT, with perceived peer engagement and negative peer perception being the greater risk factors. At the individual level, a similar pattern emerged-self-DSMT level and negative self-perception had noticeably stronger associations with digital stress than did positive self-perception.

Early adversity and sexual diversity: the importance of self-reported and neurobiological sexual reward sensitivity

Work shows that sexually-diverse individuals face high rates of early life adversity and in turn increased engagement in behavioral outcomes traditionally associated with adversity, such as sexual risk taking. Recent theoretical work suggests that these associations may be attributable to heightened sexual reward sensitivity among adversity-exposed women. We aimed to test these claims using a combination of self-report and EEG measures to test the relationship between early adversity, sexual reward sensitivity (both self-reported and EEG measured) and sexual risk taking in a sexually diverse sample of cis-gender women (N = 208) (Mage = 27.17, SD = 6.36). Results showed that childhood SES predicted self-reported sexual reward sensitivity which in turn predicted numbers of male and female sexual partners. In contrast we found that perceived childhood unpredictability predicted neurobiological sexual reward sensitivity as measured by EEG which in turn predicted male sexual partner number. The results presented here provide support for the notion that heightened sexual reward sensitivity may be a pathway through which early life adversity augments future sexual behavior, and underscores the importance of including greater attention to the dynamics of pleasure and reward in sexual health promotion.

Autonomic brain functioning and age-related health concerns

The autonomic nervous system (ANS) regulates involuntary bodily functions such as blood pressure, heart rate, breathing, and digestion, in addition to controlling motivation and behavior. In older adults, the ANS is dysregulated, which changes the ability of the ANS to respond to physiological signals, regulate cardiovascular autonomic functionality, diminish gastric motility, and exacerbate sleep problems. For example, a decrease in heart rate variability, or the variation in the interval between heartbeats, is one of the most well-known alterations in the ANS associated with health issues, including cardiovascular diseases and cognitive decline. The inability to perform fundamental activities of daily living and compromising the physiological reactivity or motivational responses of older adults to moving toward or away from specific environmental stimuli are significant negative consequences of chronic and geriatric conditions that pose grave threats to autonomy, health, and well-being. The most updated research has investigated the associations between the action responsiveness of older adults and the maintenance of their physiological and physical health or the development of mental and physical health problems. Once autonomic dysfunction may significantly influence the development of different age-related diseases, including ischemic stroke, cardiovascular disease, and autoimmune diseases, this review aimed to assess the relationship between aging and autonomic functions. The review explored how motivational responses, physiological reactivity, cognitive processes, and lifelong developmental changes associated with aging impact the ANS and contribute to the emergence of health problems.

Characterizing the mechanisms of social connection

Understanding how individuals form and maintain strong social networks has emerged as a significant public health priority as a result of the increased focus on the epidemic of loneliness and the myriad protective benefits conferred by social connection. In this review, we highlight the psychological and neural mechanisms that enable us to connect with others, which in turn help buffer against the consequences of stress and isolation. Central to this process is the experience of rewards derived from positive social interactions, which encourage the sharing of perspectives and preferences that unite individuals. Sharing affective states with others helps us to align our understanding of the world with another's, thereby continuing to reinforce bonds and strengthen relationships. These psychological processes depend on neural systems supporting reward and social cognitive function. Lastly, we also consider limitations associated with pursuing healthy social connections and outline potential avenues of future research.

Developmental Changes in Habenular and Striatal Social Reinforcement Responsivity Across Adolescence Linked With Substance Use

BACKGROUND

Habenula (HB) function is implicated in substance use disorders and is involved in inhibiting dopamine release in the ventral striatum (VS). While blunted VS reward responsivity is implicated in risk for later substance use, links between HB reinforcement processing and progression of use have not, to our knowledge, been examined among adolescents. In the present study, we longitudinally assessed HB and VS responsivity to social rewards and punishments across adolescence and examined associations with substance use.

METHODS

Within a longitudinal design, 170 adolescents (53.5% female) completed 1 to 3 functional magnetic resonance imaging scans across 6th to 9th grade and reported yearly substance use across 6th to 11th grade. We examined VS and HB responsivity to social reinforcement during a social incentive delay task in which adolescents received social rewards (smiling faces) and punishments (scowling faces).

RESULTS

We observed increased VS responsivity to social rewards (vs. reward omissions) and increased VS, but decreased HB, responsivity to social punishment avoidance versus receipt. However, contrary to hypotheses, the HB displayed increased responsivity to social rewards (vs. reward omissions). Further, adolescents reporting regular substance use displayed longitudinally declining HB responsivity to social rewards (vs. reward omissions), whereas adolescents reporting no substance use displayed longitudinally increasing HB responsivity. In contrast, whereas VS responsivity to punishment avoidance versus receipt increased longitudinally among regular substance users, it stayed relatively stable among nonusers.

CONCLUSIONS

These results suggest that differential HB and VS social reinforcement processing trajectories across adolescence are associated with substance use.

Neural sensitivity to social reward predicts links between social behavior and loneliness in youth during the COVID-19 pandemic

Neural reward network sensitivity in youth is proposed to differentially impact the effects of social environments on social outcomes. The COVID-19 pandemic provided an opportunity to test this hypothesis within a context of diminished in-person social interaction. We examined whether neural sensitivity to interactive social reward moderates the relationship between a frequency of interactive or passive social activity and social satisfaction. Survey reports of frequency of interactions with friends, passive social media use, and loneliness and social satisfaction were gathered in 2020 during mandated precautions limiting in-person contact. A subset of participants (age = 10-17) previously participated in a functional magnetic resonance imaging (fMRI) study examining social-interactive reward during a simulated peer interaction (survey n = 76; survey + fMRI n = 40). We found evidence of differential response to social context, such that youth with higher neural reward sensitivity showed a negative association between a frequency of interactive connections with friends and a combined loneliness and social dissatisfaction component (LSDC) score, whereas those with lower sensitivity showed the opposite effect. Further, high reward sensitivity was associated with greater LSDC as passive social media use increased, whereas low reward sensitivity showed the opposite. This indicates that youth with greater sensitivity to social-interactive reward may be more susceptible to negative effects of infrequent contact than their low reward-sensitive counterparts, who instead maintain social well-being through passive viewing of social content. These differential outcomes could have implications for supporting youth during times of major social disruption as well as ensuring mental health and well-being more broadly.

Neural Reactivity to Social Punishment Predicts Future Engagement in Nonsuicidal Self-injury Among Peer-Rejected Adolescents

BACKGROUND

Rates of nonsuicidal self-injury (NSSI) increase dramatically in adolescence. Affective reactivity and adverse social experiences have been linked to NSSI, but less is known about whether these factors may separately or interactively predict NSSI, especially longitudinally. This study combined functional magnetic resonance imaging and a sociometric measure to test whether a combination of neural (e.g., amygdala) reactivity to social punishment and peer-nominated peer acceptance/rejection predicts NSSI longitudinally in adolescence. Amygdala reactivity was examined as a potential neural marker of affective reactivity to social punishment, which may heighten NSSI risk in contexts of social adversity.

METHODS

One hundred twenty-five adolescents (63 female) completed a social incentive delay task during neuroimaging and school-based peer nominations to measure peer acceptance/rejection. NSSI engagement was assessed at baseline and 1-year follow-up.

RESULTS

Greater amygdala reactivity to social punishment predicted greater NSSI engagement 1 year later among adolescents with high peer rejection. This effect for the amygdala was specific to social punishment (vs. reward) and held when controlling for biological sex and pubertal development. Exploratory analyses found that ventral striatum reactivity to social reward and punishment similarly interacted with peer rejection to predict NSSI but that amygdala connectivity with salience network regions did not.

CONCLUSIONS

Amygdala reactivity to social punishment, in combination with high peer rejection, may increase NSSI risk in adolescence, possibly via heightened affective reactivity to adverse social experiences. Objective measures of neurobiological and social risk factors may improve prediction of NSSI, while therapeutic approaches that target affective reactivity and increase prosocial skills may protect against NSSI in adolescence.

Risks and rewards in adolescent decision-making

Adolescent decision-making has been characterized as risky, and a heightened reward sensitivity may be one of the aspects contributing to riskier choice-behavior. Previous studies have targeted reward-sensitivity in adolescence and the neurobiological mechanisms of reward processing in the adolescent brain. In recent examples, researchers aim to disentangle the contributions of risk- and reward-sensitivity to adolescent risk-taking. Here, we discuss recent findings of adolescent's risk preferences and the associated neural mechanisms. We highlight potential frameworks that target individual differences in risk preferences in an effort to understand adolescent risk-taking, and with an ultimate goal of leveraging undesirable levels of risk taking.

Intrinsic connectivity within the affective salience network moderates adolescent susceptibility to negative and positive peer norms

Not all adolescents are equally susceptible to peer influence, and for some, peer influence exerts positive rather than negative effects. Using resting-state functional magnetic resonance imaging, the current study examined how intrinsic functional connectivity networks associated with processing social cognitive and affective stimuli predict adolescents' (n = 87, ages 11-14 years) prosocial tendencies and risky behaviors in the context of positive and negative peer norms. We tested the moderating role of four candidate intrinsic brain networks-associated with mentalizing, cognitive control, motivational relevance, and affective salience-in peer influence susceptibility. Only intrinsic connectivity within the affective salience network significantly moderated the association between peer norms and adolescent behavior above and beyond the other networks. Adolescents with high intrinsic connectivity within the affective salience network reported greater prosocial tendencies in contexts with more positive peer norms but greater risk-taking behavior in contexts with more negative peer norms. In contrast, peer norms were not associated with adolescent behavior for individuals with low affective salience within-network intrinsic connectivity. The mentalizing network, cognitive control network, and motivational relevance network were not associated with individual differences in peer influence susceptibility. This study identifies key neural mechanisms underlying differential susceptibility to positive and negative peer influence in early adolescence, with a particular emphasis on the role of affective salience over traditional mentalizing, regulatory, and motivational processes.

The brain in social context: A systematic review of substance use and social processing from adolescence to young adulthood

Substance use escalates between adolescence and young adulthood, and most experimentation occurs among peers. To understand underlying mechanisms, research has focused on neural response during relevant psychological processes. Functional magnetic resonance imaging (fMRI) research provides a wealth of information about brain activity when processing monetary rewards; however, most studies have used tasks devoid of social stimuli. Given that adolescent neurodevelopment is sculpted by the push-and-pull of peers and emotions, identifying neural substrates is important for intervention. We systematically reviewed 28 fMRI studies examining substance use and neural responses to stimuli including social reward, emotional faces, social influence, and social stressors. We found substance use was positively associated with social-reward activity (e.g., in the ventral striatum), and negatively with social-stress activity (e.g., in the amygdala). For emotion, findings were mixed with more use linked to heightened response (e.g., in amygdala), but also with decreased response (e.g., in insula). For social influence, evidence supported both positive (e.g., cannabis and nucleus accumbens during conformity) and negative (e.g., polydrug and ventromedial PFC during peers' choices) relations between activity and use. Based on the literature, we offer recommendations for future research on the neural processing of social information to better identify risks for substance use.

The personality and cognitive traits associated with adolescents' sensitivity to social norms

Little is known about the personality and cognitive traits that shape adolescents' sensitivity to social norms. Further, few studies have harnessed novel empirical tools to elicit sensitivity to social norms among adolescent populations. This paper examines the association between sensitivity to norms and various personality and cognitive traits using an incentivised rule-following task grounded in Game Theory. Cross-sectional data were obtained from 1274 adolescents. Self-administered questionnaires were used to measure personality traits as well as other psychosocial characteristics. Incentivised rule-following experiments gauged sensitivity to social norms. A series of multilevel mixed effects ordered logistic regression models were employed to assess the association between sensitivity to norms and the personality and cognitive traits. The results highlighted statistically significant univariate associations between the personality and cognitive traits and sensitivity to norms. However, in the multivariate adjusted model, the only factor associated with sensitivity to norms was gender. The gender-stratified analyses revealed differences in the personality and cognitive traits associated with sensitivity to norms across genders. For males need to belong was significantly negatively associated with sensitivity to norms in the multivariate model. By comparison, emotional stability was negatively associated with sensitivity to norms for females. This study reinforced the findings from an earlier study and suggested female adolescents had higher levels of sensitivity to norms. The results indicated no consistent pattern between sensitivity to norms and the personality and cognitive traits. Our findings provide a basis for further empirical research on a relatively nascent construct, and bring a fresh perspective to the question of norm-following preferences among this age group.

Service innovation in small neighborhood family firms: An advanced approach to enhance employee's performance through social and psychological rewards

This research study focuses on the employee's job performance of private small firms during the post COVID-19 situation. After the COVID these small family firms try to regain their business, but their efforts are not that much successful. This situation creates a financial crisis in these firms, and they are unable to provide sufficient monetary rewards to their employees. This situation creates unrest among the employees of these small firms. To manage this issue, social rewards and psychological rewards played their role. The study uses a causal research design with a correlational study design in a non-contrived environment. Minimal researcher interference has been assured. AMOS 24 has dealt with the mediation in study design with bootstrap methodology. The study was conducted on 250 employees of different private small family firms across Punjab province using a proportionate stratified sampling technique. A study's finding suggests that top management enhances employee performance in their organizations by introducing the organization's psychological rewards. In contrast, introducing social rewards does not significantly impact employee performance while considering satisfaction and motivation as a mediating variable.

What Does it Mean to be Susceptible to Influence? A Brief Primer on Peer Conformity and Developmental Changes that Affect it

Peer influence is a twofold process that entails a behavior by an agent of influence that elicits conformity from the target of influence. Susceptibility describes the likelihood that conformity will occur. This review focuses on factors that shape susceptibility to peer influence. We argue that conformity has two distinct sources. In some instances, conformity is a product of characteristics of the target of influence, operationalized as stable individual difference variables. Trait-like attributes associated with susceptibility to peer influence include conformity dispositions, social goals, resource acquisition strategies, vulnerabilities, and maturational status. In other instances, conformity is a product of the context in which the target is situated, operationalized as impermanent individual difference variables. State-like circumstances associated with susceptibility to peer influence include conditions of uncertainty, personal attributes that differ from the partner or group, perceived benefits of impression management, unmet social needs, and social referents and beliefs about their behavior. Empirical illustrations are provided. We close with a discussion of developmental changes hypothesized to impact variations in susceptibility to peer influence.

Early experience unpredictability in child development as a model for understanding the impact of the COVID-19 pandemic: A translational neuroscience perspective

Extensive evidence links adverse experiences during childhood to a wide range of negative consequences in biological, socioemotional, and cognitive development. Unpredictability is a core element underlying most forms of early adversity; it has been a focus of developmental research for many years and has been receiving increasing attention recently. In this article, we propose a conceptual model to describe how unpredictable and adverse early experiences affect children's neurobiological, behavioral, and psychological development in the context of the COVID-19 pandemic. We first highlight the critical role of unpredictability in child development by reviewing existing conceptual models of early adversity as they relate to subsequent development across the lifespan. Then, we employ a translational neuroscience framework to summarize the current animal- and human-based evidence on the neurobiological alterations induced by early experience unpredictability. We further argue that the COVID-19 pandemic serves as a global "natural experiment" that provides rare insight to the investigation of the negative developmental consequences of widespread, clustered, and unpredictable adverse events among children. We discuss how the pandemic helps advance the science of unpredictable early adverse experiences. As unpredictability research continues to grow, we highlight several directions for future studies and implications for policymaking and intervention practices.

Introduction to the special section on susceptibility to peer influence

This introduction outlines the goals for the special section on susceptibility to peer influence and articulates aims for the next research steps. We emphasize the difference between state and trait definitions of conformity, a distinction that helps clarify the contributions of specific research findings and delineates areas in need of greater research attention.

Adolescent decision making: A decade in review

Research in the past decade has highlighted the nuances of adolescent decision making. In this review article, we summarize several themes evident in the field of developmental science including the redefinition of adolescence and the ways in which adolescent decision-making capabilities converge with or diverge from those of adults. While the decision-making process is similar for adolescents and adults in contexts that encourage deliberation and reflection, adolescents and adults differ in contexts which preclude deliberation vis-à-vis high emotional arousal. We also discuss the reconceptualization of adolescent behavior, including risk taking, as adaptive. That is, characteristics of adolescence, including impulsivity, the importance of peers, and novelty seeking, are normative, evolutionarily advantageous, and essential for positive development. While these features manifest in negative, health-compromising ways (e.g., risky driving and criminal behavior), they also foster growth and exploration. We conclude with a discussion of potential avenues for future research.

Amygdalar Activation as a Neurobiological Marker of Differential Sensitivity in the Effects of Family Rearing Experiences on Socioemotional Adjustment in Youths

BACKGROUND

Substantial heterogeneity exists in how rearing environments influence youths' socioemotional outcomes. This heterogeneity, as suggested by the biological sensitivity to context theory and the differential susceptibility theory, is associated with emotional reactivity patterns and underlying neural functions. The present study investigated amygdalar reactivity to emotional stimuli as a neural signature that amplified the influence of rearing environments on youths' socioemotional outcomes.

METHODS

To increase replicability and generalizability, this investigation included two independent studies that methodologically complemented each other. Study 1 employed a large, national, longitudinal dataset (the Adolescent Brain Cognitive Development study; N = 11,875). Study 2 used a community sample of youths (N = 123) with multimethod and multireporter assessments.

RESULTS

In study 1, high left amygdalar reactivity to positive stimuli significantly amplified the impact of parental warmth on youths' prosocial behaviors. In study 2, left and right amygdalar reactivity to positive stimuli significantly intensified the associations between family functioning and youths' internalizing problems. These findings were consistent with the biological sensitivity to context theory/differential susceptibility theory hypothesis because significant socioemotional differences were observed at both negative and positive extremes of rearing environments. Additionally, study 2 partially supported the diathesis-stress hypothesis by showing significant differences in youths' vulnerability to negative family environments. Specifically, left amygdalar response to negative stimuli exacerbated the associations between unbalanced family functioning and heightened internalizing/externalizing symptoms. Left amygdalar reactivity to positive stimuli intensified the link between unbalanced family functioning and elevated externalizing problems.

CONCLUSIONS

Among youths and adolescents, amygdalar emotional reactivity may serve as a biomarker of differential sensitivity to rearing environments.

Social neural sensitivity as a susceptibility marker to family context in predicting adolescent externalizing behavior

Adolescence represents a period of risk for developing patterns of risk-taking and conduct problems, and the quality of the family environment is one robust predictor of such externalizing behavior. However, family factors may not affect all youth uniformly, and individual differences in neurobiological susceptibility to the family context may moderate its influence. The current study investigated brain-based individual differences in social motivational processing as a susceptibility marker to family conflict in predicting externalizing behavior in early adolescent youth. 163 adolescents (M_age = 12.87 years) completed an fMRI scan during which they anticipated social rewards and social punishments. For adolescents with heightened ventral striatum and amygdala blood oxygen-level dependent (BOLD) response during the anticipation of social rewards and heightened ventral striatum BOLD response during the anticipation of social punishments, higher levels of family conflict were associated with greater externalizing behavior. BOLD response when anticipating both social rewards and punishments suggested increased susceptibility to maladaptive family contexts, highlighting the importance of considering adolescent social motivation in positive and negatively valenced contexts.

Differences in Adolescents' Alcohol Use and Smoking Behavior between Educational Tracks: Do Popularity Norms Matter?

Explanations about differences in drinking and smoking rates between educational tracks have so far mainly focused on factors outside the classroom. The extent to which these behaviors are rewarded with popularity within a classroom—so called popularity norms—and their interaction with individual characteristics could explain the observed differences in risk behavior. 1860 adolescents (M_age = 13.04; 50% girls) from 81 different classrooms reported three times during one academic year about their own and their classmates behavior. Overall, in vocational tracks popularity norms for alcohol and smoking were more positive and predicted classroom differences in alcohol and smoking. Knowledge about classroom processes can advance the field in unraveling the functional aspects of risk behavior in adolescence. Preregistration: The hypotheses and the analytical plan of this study were preregistered under number #39136 (https://aspredicted.org/blind.php?x=gx77p6).