Is the Peer Presence Effect on Heightened Adolescent Risky Decision-Making only Present in Males?

Methamphetamine increases risky choice in rats, but only when magnitude and probability of reinforcement are manipulated within a session

Risky choice is associated with maladaptive behaviors, particularly substance use disorders. Current animal models of risky choice are often confounded by other constructs like behavioral flexibility and suboptimal choice. The purpose of the current experiment was to determine if the psychostimulant methamphetamine, a drug whose popularity has increased in recent years, increases risky choice in an equivalent expected value (EEV) task. In the EEV task, rats are given a choice between two reinforcer alternatives that differ in magnitude and probability of delivery, but have equivalent expected value. Forty-eight Sprague Dawley rats were tested in three versions of the EEV task. In the first version of the EEV task, both reinforcer magnitude and probability were adjusted across blocks of trials for both alternatives. In the second and the third versions of the EEV task, reinforcer magnitude was held constant across each block of trials (either 1 vs. 2 pellets or 4 vs. 5 pellets). We found that male rats preferred the "riskier" option, except when reinforcer magnitudes were held constant at 4 and 5 pellets across each block of trials. Methamphetamine (0.5 mg/kg) increased preference for the risky option in both males and females, but only when both reinforcer magnitude and probability were manipulated across blocks of trials for each alternative. The current results demonstrate that both magnitude of reinforcement and probability of reinforcement interact to influence risky choice. Overall, this study provides additional support for using reinforcers with expected value to measure risky choice.

The more peers are present, the more adventurous? How peer presence influences adolescent pedestrian safety

Objective

Adolescence is a high-risk period for traffic injury. One factor that may impact adolescent safety in traffic is the presence of peers. We conducted a quasi-experimental research study to examine the impact of peer presence, peer familiarity, and peer group size on adolescent pedestrian risk-taking intentions in both sidewalk and street-crossing settings.

Methods

607 students aged 12-18 years from Nantong city, China, completed a questionnaire that presented 20 traffic scenarios. The scenarios varied based on a 3 (peer group size: no peer vs. one peer vs. multiple peers) x 2 (peer familiarity: familiar vs. unfamiliar) x 2 (traffic setting: crossing the street vs. walking on the roadside) experimental design. Adolescents' responses indicated safer vs riskier intentions in each situation.

Results

Results found that: (1) Adolescents were safer when walking on the sidewalk than when crossing the street; (2) Whether crossing the street or walking on the sidewalk, adolescents' behavioral intentions were safer when there were peers present than when there were no peers present; (3) Adolescents' safety tended to be higher overall with unfamiliar peers than with familiar peers; (4) Adolescents were less safe when crossing the street with familiar peer(s) than with unfamiliar peer(s), but no differences emerged when walking on the sidewalk.

Conclusions

Adolescents report safer behavior when walking with a peer or peers compared with walking alone. Familiar peers reduce adolescents' safety of behavior intentions in traffic, especially when crossing the street.

Research Review: Siblings matter. A multi-level meta-analysis on the association between cannabis use among adolescent siblings

BACKGROUND

Parents' and peers' cannabis use are well-documented predictors of youth cannabis use, however, relatively little is known about the influence of siblings' cannabis use. Hence, this meta-analysis investigated the association between sibling-youth cannabis use (disorder) and explored moderation by sibling type (monozygotic- vs. dizygotic- vs. non-twins), age, age spacing, birth order, gender, and gender constellations (same- vs. mix- gender pairs). When comparison data of parents' and peers' cannabis use (disorder) were also available in the included studies, separate meta-analyses on associations between parent-youth and peer-youth cannabis use (disorder) were additionally conducted.

METHODS

Studies were selected if they included 11- to 24-year-old participants, and investigated associations between cannabis use (disorder) among those youth and their siblings. These studies were retrieved via a search in seven databases (e.g., PsychINFO). A multi-level meta-analysis using a random effects model was performed on the studies, and heterogeneity analyses and moderator analyses were also conducted. PRISMA guidelines were followed.

RESULTS

We retrieved 20 studies (most of which originated from Western cultures) with 127 effect sizes for the main sibling-youth meta-analysis and found a large overall effect-size (r = .423), implying that youth had higher cannabis use rates when their sibling used cannabis, and this association was stronger for monozygotic twins and for same-gender sibling pairs. Finally, a medium effect size existed for the associations between parent-youth cannabis use (r = .300) and a large effect size for peer-youth cannabis use (r = .451).

CONCLUSIONS

Youth are more likely to use cannabis when their siblings use cannabis. This sibling-youth cannabis use association existed for all sibling constellations, was larger than the association between parent-youth cannabis use, and was similar in magnitude compared to the association between peer-youth cannabis use-suggesting both genetic and environmental influences (e.g., social-learning) between siblings. Hence, it is important not to neglect sibling influences when treating youth cannabis use (disorder).

Are you more risk-seeking when helping others? Effects of situational urgency and peer presence on prosocial risky behavior

Introduction

Prosocial risky behavior (PRB) proposes that individuals take risks for others' benefits or social welfare, and that this may involve trade-offs between risk and social preferences. However, little is known about the underlying cognitive mechanisms of risk-seeking or aversion during PRB.

Methods

This study adopted the dilemma-priming paradigm to examine the interaction between the risk levels of personal cost and situational urgency on PRB (Experiment 1, N  = 88), and it further uncovered the modulation of the risk levels of failure (Experiment 2, N  = 65) and peer presence (Experiment 3, N  = 80) when helping others.

Results

In Experiment 1, the participants involved in risky dilemmas made more altruistic choices for strangers in urgent situations compared to those for strangers in non-urgent situations. However, increasing the risk levels of personal cost decreased the frequencies of help offered to strangers in urgent situations. Experiment 2 further established that, similar to the risk of personal cost, increasing the risk levels of failure when helping others also decreased the frequencies of help offered to strangers in urgent situations. Furthermore, in dilemmas involving a low-risk personal cost, Experiment 3 showed that peer presence encouraged the participants to make more altruistic choices when providing help to strangers in non-urgent situations.

Discussion

Individuals demonstrate obvious risk-seeking behavior when helping others and that both non-urgent situations and peer presence weaken the effect of increased risk aversion on PRB in a limited manner.

Explore with Me: Peer Observation Decreases Risk-Taking but Increases Exploration Tendencies across Adolescence

It has been assumed that adolescents increase risk-taking tendencies when peers are present but findings on experimental decision-making have been inconclusive. Most studies focus on risk-taking tendencies, ignoring the effects peer presence can exert over other cognitive processes involved in decision-making, as well as any other underlying developmental and individual differences. In the present study, the trial-by-trial choice behavior was analyzed in a task in which adolescents adjust to dynamically changing risk probabilities. Using Bayesian modeling, the study aimed to infer about peer presence effects on risk-taking tendencies but also on reactions to, exploration of, and learning from positive and negative outcomes of risk-taking. 184 pre- to late adolescents (M = 14.09 years, min = 8.59, max = 18.97, SD = 2.95, 47% female) conducted the Balloon Analog Risk Task under two conditions: Once alone and once in the presence of a (non-existent) peer observing them virtually. Findings revealed that (a) peer observation reduced risk-taking but increased exploration tendencies and (b) that individual differences modulated this effect. Especially female pre-adolescents increased their openness to explore different choice outcomes when a peer observed their behavior. These results support the assumption that the occurrence and direction of peer influences on risk-taking depend on a person-environment interaction, emphasizing the dynamic role peers play in adolescent risk-taking.

The Influence of Social Isolation on Social Orientation, Sociability, Social Novelty Preference, and Hippocampal Parvalbumin-Expressing Interneurons in Peripubertal Rats - Understanding the Importance of Meeting Social Needs in Adolescence

The fulfillment of belonging needs underlies a variety of behaviors. In order to understand how social needs unmet during maturation shape everyday life, we examined social motivation and cognition in peripubertal rats, as a rodent model of adolescence, subjected to social isolation (SI) during early and early-to-mid adolescence. The behavioral correlates of social orientation (social space preference), sociability (preference for social over non-social novelty), and social novelty preference (SNP) were examined in group-housed (GH) and single-housed (SH) rats in a 3-chamber test. The response to social odors was examined to gain insights into the developmental role of social odors in motivated social behavior. Differentiation between appetitive (number of visits/approaches) and consummatory (exploratory time) aspects of motivated social behavior was done to determine which facet of social motivation characterizes maturation when social needs are met and which aspect dominates when social needs are unsatisfied. The SI-sensitive parvalbumin-expressing interneurons (PVI) in the hippocampus were examined using immunohistochemistry. The main findings are the following: (1) in GH rats, the preference for social space is not evident regardless of animals' age, while sociability becomes apparent in mid-adolescence strictly through consummatory behavior, along with complete SNP (appetitive, consummatory); (2) SH promotes staying in a social chamber/space regardless of animals' age and produces an appetitive preference for it only in early-adolescent animals; (3) SH promotes sociability (appetitive, consummatory) regardless of the animals' age and prevents the SNP; (4) the preference for a social odor is displayed in all the groups through consummatory behavior, while appetitive behavior is evident only in SH rats; (5) the response to social odors does not commensurate directly to the response to conspecifics; (6) SH does not influence PVI in the hippocampus, except in the case of early-adolescence when a transient decrease in the dentate gyrus is observed. These results accentuate the developmental complexity of social motivation and cognition, and the power of SI in adolescence to infringe social maturation at different functional levels, promoting appetitive behavior toward peers overall but harming the interest for social novelty. The findings emphasize the importance of the fulfillment of basic social needs in the navigation through the social world.

Adolescent school injuries and classroom sex compositions in German secondary schools

BACKGROUND

School injuries are an important adolescent health problem. Previous research suggests that relevant risk behaviors for school injuries, risk-taking and aggression, are highly susceptible to peer effects. Specifically, evidence suggests that the ratio of men and women in peer groups (sex ratio) affects individuals' propensity for aggression and risk-taking. However, potential associations of classroom sex ratios with adolescent school injury risks have not been studied so far. The purpose of this paper is to investigate the association of classroom sex compositions with adolescent school injuries.

METHODS

We investigate the association of classroom sex ratios with school injuries in a longitudinal survey dataset containing 13,131 observations from 9,204 adolescent students (ages 13-16) from secondary schools in Germany. The data also allow us to identify injuries due to aggressive behavior and analyze these injuries in detail. We use multilevel logistic regression models to analyze risks of both overall and aggression-related school injuries.

RESULTS

Adolescent students' risk for school injuries is significantly and positively associated with male-skewed classroom sex ratios (OR = 1.012, p=0.012). Specifically, the risk of sustaining a school injury increases by 33.5 percent when moving from the 10th to the 90th classroom sex ratio percentile. Moreover, we find an even stronger positive association between male-dominated classrooms and aggression-related injury risks (OR = 1.022, p=0.010). Compared to classroom sex ratios at the 10th percentile, the risk of an aggression-related injury is 78 percent higher in classrooms with a sex ratio at the 90th percentile. Finally, we find that both boys' and girls' injury risks equally increase with a higher proportion of male students in their classroom.

CONCLUSIONS

Our findings indicate that sex composition of classrooms is an important contextual factor for adolescent school injuries, in particular school injuries resulting from aggression. These findings illustrate the need to integrate a contextual perspective on school injuries among adolescent students both into research and into intervention planning.

Adolescent Brain Development and Contextual Influences: A Decade in Review

Adolescence is a developmental period characterized by substantial psychological, biological, and neurobiological changes. This review discusses the past decade of research on the adolescent brain, as based on the overarching framework that development is a dynamic process both within the individual and between the individual and external inputs. As such, this review focuses on research showing that the development of the brain is influenced by multiple ongoing and dynamic elements. It highlights the implications this body of work on behavioral development and offers areas of opportunity for future research in the coming decade.

Preference uncertainty accounts for developmental effects on susceptibility to peer influence in adolescence

Adolescents are prone to social influence from peers, with implications for development, both adaptive and maladaptive. Here, using a computer-based paradigm, we replicate a cross-sectional effect of more susceptibility to peer influence in a large dataset of adolescents 14 to 24 years old. Crucially, we extend this finding by adopting a longitudinal perspective, showing that a within-person susceptibility to social influence decreases over a 1.5 year follow-up time period. Exploiting this longitudinal design, we show that susceptibility to social influences at baseline predicts an improvement in peer relations over the follow-up period. Using a Bayesian computational model, we demonstrate that in younger adolescents a greater tendency to adopt others’ preferences arises out of a higher uncertainty about their own preferences in the paradigmatic case of delay discounting (a phenomenon called ‘preference uncertainty’). This preference uncertainty decreases over time and, in turn, leads to a reduced susceptibility of one’s own behaviour to an influence from others. Neuro-developmentally, we show that a measure of myelination within medial prefrontal cortex, estimated at baseline, predicts a developmental decrease in preference uncertainty at follow-up. Thus, using computational and neural evidence, we reveal adaptive mechanisms underpinning susceptibility to social influence during adolescence.

People often change their preferences to conform with others. Using a longitudinal design, the authors show that such conformity decreases over the course of adolescence and that this reduction in conformity is accompanied by a decreasing degree of uncertainty about what to like.

Sex differences in pubertal associations with fronto-accumbal white matter morphometry: Implications for understanding sensitivity to reward and punishment

Researchers have reported sex-differentiated maturation of white matter (WM) during puberty. It is not clear, however, whether such distinctions contribute to documented sex differences in sensitivity to reward and punishment during adolescence. Given the role of the orbitofrontal cortex (OFC) and nucleus accumbens (NAcc) in reward and punishment-related behaviors, we tested in a cross-sectional study whether males and females (N = 156, 89 females; ages 9-14 years) differ in the association between pubertal stage and fixel-based morphometry of WM fibers connecting the OFC and NAcc (i.e., the fronto-accumbal tract). Further, we examined whether males and females differ in associations between fronto-accumbal WM measures and self-reported sensitivity to reward and punishment. Pubertal stage was positively associated with fronto-accumbal fiber density and cross-section (FDC) in males, but not in females. Consistent with previous reports, males reported higher reward sensitivity than did females, although fronto-accumbal combined FDC was not related to reward sensitivity in either sex. Meanwhile, only males showed a negative association between fronto-accumbal tract FDC and sensitivity to punishment. Follow-up analyses revealed that fiber cross-section, but not density, was related to pubertal stage and punishment sensitivity in males, as well as to reward sensitivity in all participants. Our findings suggest there are sex differences in puberty-related maturation of the fronto-accumbal tract, and this tract is related to lower punishment sensitivity in adolescent males compared to females.