Instead our results converge with past reports that show continued linear declines in extraversion in late adolescence in male youth , and stable levels of extraversion in late adolescence for female youth . As described in a recent review, findings on mean-level change in extraversion continue to be inconsistent ; however, our findings seem to link together several previous reports, and suggest that flexible modeling are necessary to capture sex-specific effects in the development of reported extraversion. For emotional stability, our findings continue to fit well with past literature. Like others , we find steady increases in emotional stability in male participants across the entire developmental age range, while female participants demonstrate a dip in emotional stability during mid-adolescence, followed by a slight rise, before largely leveling off in late adolescence and early adulthood. Again, we note an important difference here between our GAMM findings and quadratically- and cubically-fit linear models. Our LME model results suggest that in male participants, emotional stability rises slightly during early- and mid-adolescence before declining in late-adolescence and early adulthood . While this effect in male youth has been demonstrated previously , we found that after controlling for substance use, and using more flexible non-linear modeling strategies, a linear fit was better in male youth. Therefore, like with extraversion, vertical farming racks our findings replicate several previous results, and suggest that disparate findings may be due to different modeling strategies.
In general, the sex differences noted in our sample are highly convergent with past literature. That is, female youth typically report greater extraversion, openness, agreeableness, and conscientiousness, and less emotional stability, and these effects for openness, agreeableness and conscientiousness are persistent throughout adolescence and young adulthood , while past findings regarding the developmental timing of sex differences in extraversion and emotional stability have been less clear. Our findings provide added support for the existing notion that the largest differences in emotional stability and extraversion between male and female youth emerge by mid-to-late adolescence and persist into young adulthood . These findings, particularly in regards to emotional stability, may have relevance for sex differences in rates of internalizing mental health disorders, with women showing much higher rates of depression than men, beginning during adolescence . Regarding the association between substance use and personality, our results fit with past literature. Like others , we see that alcohol use is associated with lower conscientiousness and higher extraversion, though our findings suggest the association between alcohol use and conscientiousness may be limited to adolescence, dissipating in young adulthood. Further, we replicate past reports of greater marijuana use being associated with less agreeableness, conscientiousness and emotional stability ; however, our results suggest these associations between marijuana use and conscientiousness are limited to early adolescence and later in young adulthood.Importantly, we replicate previous reports of alcohol and marijuana use being differentially related to extraversion , particularly in young adulthood , highlighting the importance of examining their effects concurrently.
Additionally, while past reports found the association between marijuana use and emotional stability was stronger in female youth than male youth , we found that greater marijuana use was associated with lower emotional stability throughout adolescence and young adulthood for female youth, but only in young adulthood for male youth. Lastly, in contradiction to past literature, we found alcohol use was associated with higher openness. However, as noted in regards to the developmental increase in openness we found, it is possible that the 10-item measure of personality may not have reliably captured this trait. Thus, these results should be interpreted with caution. In young adults, lower emotional stability has been associated with using marijuana as a coping mechanism, an effect mediated by anxiety sensitivity ; however, young adults with lower conscientiousness are also more likely to experience negative consequences related to their marijuana use . This suggests that adolescents and young adults with lower conscientiousness and emotional stability may be more prone to using marijuana as a method for managing stress and anxiety, but may also be more likely to experience negative consequences of their drug use, and that female youth may be more susceptible to these effects. Meanwhile, previous studies demonstrated that extraversion is associated with positive alcohol expectancies and that alcohol expectancies mediate the relationship between extraversion and alcohol use , suggesting that those reporting higher extraversion may be more inclined to drink alcohol for its prosocial effects. Finally, strengths and weaknesses regarding our modeling techniques should be noted. First, our GAMMs produced subtle but important differences compared to LME models in the development of extraversion in females and emotional stability in males. While our LME results, using lower-order polynomial effects, may align with singular past studies, our GAMM results help bring convergence to several past studies, some of which had more narrow age ranges.
However, GAMMs do not provide parametric coefficients for growth parameters, even in the case of linear growth, making it difficult to assess of effect sizes for both change across age and age-dependent sex-specific effects. Here, simultaneously fitting traditional polynomial effects , where appropriate, may be of added benefit. Future studies should consider using GAMMs as an exploratory analytic first step in identifying subtle changes in personality over time, before following up with traditional linear models. Several additional limitations should also be noted. First, while our goal was to evaluate the development of personality in association between past-year substance use, it is difficult to determine from our models whether substance use is predictive of changes in personality. In fact, it is most likely that personality and substance use have bidirectional effects over the course of development. With this question in mind, a different set of modeling techniques would be necessary to test such effects. Given the broad range of timing of substance use initiation and our desire to focus on the non-linear shape of personality development, such analyses fall beyond the scope of the current report, and may be better answered by more robust single cohort longitudinal studies . Further, our measure of substance use is rather course, and does not capture the vast array of patterns and quantity of use often occurring during this developmental period. However, as is the case in most studies to date, marijuana use has proven to be difficult to properly quantify . As such, we have chosen to prioritize selection of use variables that could be equated across the two substances, so that our findings may be compared in a meaningful way. It is also the case that, for this study, we are using sex at birth as the variable of interest, in the absence of other potentially meaningful and related variables of individual difference, such as gender identity or other psychosocial or cultural factors that may influence personality. Therefore, interpretation of sex-specific findings is limited. Finally, as noted before, personality effects may be most generalizable when measured in a multimethod, multiscale, and even multinational capacity . While our findings replicate many previous results and highlight the ability of even brief measures of gaining insight into personality, their generalizability may be questioned. Future studies with similar methodological techniques, but different samples, or measures, could provide further confirmation of our results. In conclusion, we used a large, multi-site longitudinal dataset to replicate and extend several past findings on personality development in adolescence. We confirm findings of steady linear increases in agreeableness and conscientiousness across adolescence and young adulthood, and provide additional clarity regarding discrepant reporting on the development of extraversion and emotional stability. We also replicate the preponderance of literature that finds female youth report higher agreeableness, openness, conscientiousness and extraversion and lower emotional stability, compared to male youth, and provide added clarity on the developmental timing of such effects. Finally, we provide novel information regarding the timing of the association between substance use and personality, vertical grow rack and we replicate past reporting of differential associations between alcohol and marijuana use on extraversion and sex-dependent effects of marijuana use on emotional stability. Taken together, these findings highlight the importance of modeling sex differences in personality development, using flexible non-linear modeling strategies, and accounting for sex- and age-specific effects of alcohol and marijuana use.Adolescence, the transition from childhood to adulthood, is often characterized as a particularly difficult time for children . Adolescents undergo bodily and hormonal changes, which further influences their mental and physical health .
Adolescents feel misunderstood and struggle to fit in with the pressures they may feel from their peers, family, and society . Often times, this may lead to the practice of risky and harmful behaviors such as poor diet, substance use, unprotected sex, and reckless driving . These health risk behaviors can further shape adolescent health during this critical time and may even affect their decisions in adulthood, and thus it is critical to address these behaviors early on . The Centers for Disease Control and Prevention identified unhealthy eating and substance use as health risk behaviors that are particularly likely to negatively impact adolescent health . The focus on unhealthy eating is important given the increase in obesity during adolescence throughout the last decade . With the rise in obesity rates among children and adolescents in the United States, it has become vital for parents to learn effective communication strategies that may influence their children to make healthier food choices in their daily lives. Marijuana is the most commonly used illicit substance among adolescents, with the prevalence of marijuana use increasing every year in the United States . Among these adolescents, there is a decrease in adolescents perceived harm and disapproval towards marijuana use . Changes in marijuana policies have tracked with greater acceptance of marijuana use in adults and adolescents across the United States . These trends suggest that marijuana use will continue to rise with increases in legalization of marijuana for medicinal and recreational use across the United States. Though adolescents begin to desire independence from their parents, parents still play an integral role in the prevention of health risk behaviors in their children . It has been found that parent-child discussions centered on preventing risky behaviors serve as a protective influence . Weekly parent-child discussions have also been identified as one of the strongest factors in influencing healthier food choices in adolescents . Parent decisions to discuss health risk behaviors with their children are likely to be influenced by their general parenting dynamics such as their attachment styles, their parenting styles, and their communication tendencies . These parental decisions are also likely to be shaped by more proximal and behavior-specific psychological factors such as their risk perceptions of unhealthy eating and marijuana use, their social prototypes or stereotypes of children who engage in these behaviors, and their worry about the potential harms of these behaviors . In the present research project, we propose an extended adaptation of the PWM framework in which we integrate general parenting dynamics with both established PWM factors and new cognitive factors as predictors of parental discussions of unhealthy eating and marijuana use with their children . After testing this adapted PWM in Study 1, we used the model to guide the development and evaluation of discussion tools designed to provide parents with guidance on how to communicate about unhealthy eating and marijuana use with their children . There is a need for evidence-based discussion tools that will provide parents with tips on how to talk with their child about these health risk behaviors, particularly given evidence that parenting practice interventions about substance use with a communication component have been effective in increasing discussions with their child about substance use, as well as alleviating or decreasing substance use in the child . This dissertation is organized as follows. The general introduction provides an overview of the PWM including measures of perceived risks, prototypes, worry, intentions and willingness; evidence supporting the adapted PWM for predicting parental discussions of marijuana use with child; overview of attachment styles, parenting styles, parent-child communication, coherence, and self-efficacy; and lastly a summary and research overview. Then, Chapter Two will focus on Study 1, Chapter Three will focus on Study 2, Chapter Four will focus on Study 3, and Chapter Five will focus on the general discussion, limitations, and concluding remarks and recommendations.According to the PWM, two sets of psychological processes motivate risk-related behavior .