Research: Cognitive ability

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The perceived incompetence of the modern minor is exaggerated, culture-bound, and can be blamed in part on the highly lucrative "troubled teen" industry and the advocacy science surrounding it. The often-repeated myth of brain development ending at the ages of 18 or 25, started circulating in the early 10s, but has never been backed up by brain imaging evidence going beyond that age. This is the hallmark of advocacy science. Debate Guide: Teen brain, gives some rebuttals. Use in combination with the following sources:

Basic Physiology/volumes

Total brain volume and Gray Matter volume appears to reach a peak before or during puberty, declining thereafter. White matter, which has a less critical function in cognition, takes until the mid-40s to peak in volume. Neither of these represent any milestone other than the start of puberty. it is clear that some parts of the brain develop into and beyond early adulthood, while others might regress somewhat. This is a normal process of aging, since brain development and cognitive capacity is highly elastic and dependent on environment.

• Giedd, J. et al (1999). "Brain development during childhood and adolescence: a longitudinal MRI study," Nature Neuroscience, 2(10):861-3.

  "Pediatric neuroimaging studies, up to now exclusively cross sectional, identify linear decreases in cortical gray matter and increases in white matter across ages 4 to 20. In this large-scale longitudinal pediatric neuroimaging study, we confirmed linear increases in white matter, but demonstrated nonlinear changes in cortical gray matter, with a preadolescent increase followed by a postadolescent decrease. These changes in cortical gray matter were regionally specific, with developmental curves for the frontal and parietal lobe peaking at about age 12 and for the temporal lobe at about age 16, whereas cortical gray matter continued to increase in the occipital lobe through age 20. The subjects for this study were healthy boys and girls participating in an ongoing longitudinal pediatric brain-MRI project at the Child Psychiatry Branch at the National Institute of Mental Health. [...] This MRI study demonstrates a preadolescent increase in cortical gray matter; this phenomenon was previously obscured, probably by the lack of longitudinal data, as even in an analysis of the 145 cross-section-al data points in our sample, the largest to date, we could not detect nonlinearity in these developmental curves".

• Bartzokis, G. et al., (2001). "Age-related changes in frontal and temporal lobe volumes in men: a magnetic resonance imaging study," Arch Gen Psychiatry, Aug; 58(8):774.

  "Methods: Seventy healthy adult men aged 19 to 76 years underwent magnetic resonance imaging. Coronal images focused on the frontal and temporal lobes were acquired using pulse sequences that maximized gray vs white matter contrast. The volumes of total frontal and temporal lobes as well as the gray and white matter subcomponents were evaluated. Results: Age-related linear loss in gray matter volume in both frontal (r = -0.62, P<.001) and temporal (r = -0.48, P<.001) lobes was confirmed. However, the quadratic function best represented the relationship between age and white matter volume in the frontal (P<.001) and temporal (P<.001) lobes. Secondary analyses indicated that white matter volume increased until age 44 years for the frontal lobes and age 47 years for the temporal lobes and then declined. Conclusions: The changes in white matter suggest that the adult brain is in a constant state of change roughly defined as periods of maturation continuing into the fifth decade of life followed by degeneration. Pathological states that interfere with such maturational processes could result in neurodevelopmental arrests in adulthood. ."

Competence

• Epstein, Robert (2010). "Adultness," Teen 2.0, 148-157.

  "After reviewing the relevant scientific literature, interviewing many adults, and consulting with three other psychologists and two psychiatrists with expertise in adult development issues, we concluded that there are fourteen different skill-sets or "competencies" [love, sex, leadership, problem solving, physical abilities, verbal and math, interpersonal skills, responsibility, managing high-risk behaviors, work, education, personal care, self-management, and citizenship] that distinguish adults from non-adults. [...] For three of the competencies--love, leadership and problem solving--we did find statistically significant differences between the mean scores of teens and adults, with adults outscoring the teens. But the absolute differences were small. [...] On two other scales--work and self-management--the differences between the adult scores and teen scores were marginally significant (at the .05 level), again in the adults' favor, but the absolute differences were less than 4 percent. On the other nine scales, we found no significant differences at all between the adult and teen scores. [...] fifty five of the adults in our sample were college graduates--more than double the rate of college graduates in the United States."

• Epstein, Robert (2007). "The Myth of the Teen Brain," Scientific American Mind, April/May, 57-63.

  "Visual acuity, for example, peaks around the time of puberty. "Incidental memory"—the kind of memory that occurs automatically, without any mnemonic effort, peaks at about age 12 and declines through life. [...] In the 1940s pioneering intelligence researchers J. C. Raven and David Wechsler, relying on radically different kinds of intelligence tests, each showed that raw scores on intelligence tests peak between ages 13 and 15 and decline after that throughout life. Although verbal expertise and some forms of judgment can remain strong throughout life, the extraordinary cognitive abilities of teens, and especially their ability to learn new things rapidly, is beyond question. And whereas brain size is not necessarily a good indication of processing ability, it is notable that recent scanning data collected by Eric Courchesne and his colleagues at the University of California, San Diego, show that brain volume peaks at about age 14."

• Moshman, David (2011). "Adolescent Rationality and Development: Cognition, Morality, and Identity, Third Edition.

(Intro) "Adolescents are qualitatively and categorically distinct from children. There is no empirical support, however, for a state of rationality or maturity common to most adults, rately seen in adolescents. Even young adolescents often show forms and levels of rationality beyond the competence of many adults, and adults of all ages often fall short of rational standards met by many adolescents [...] it is not surprising to find that in most societies for most of human history there was no such thing as adolescence, at least as we understand it (Epstein, 2007; Grotevant, 1998; Hine, 1999)."

"Postchildhood developmental changes in thinking are not tied to age and do not culminate in a state of maturity. Although it seems likely that many individuals show progress beyond childhood in the quality of their problem solving, decision making, judgment, and planning (Cauffman & Woolard, 2005; Steinberg & Scott, 2003), the deployment and progress of thinking in adolescence and beyond is highly variable, depending on specific interests, activities, and circumstances (Fischer, Stein, & Heikkinen, 2009). No theorist or researcher has ever identified a form or level of thinking routine among adults that is rarely seen in adolescents. Adolescent thinking often develops but not through a fixed sequence and not toward a universal state of maturity [...] It seems almost irresistible for adults to see themselves as having achieved a state of maturity that adolescents (and even younger adults) have not yet reached, but brain research provides no evidence to support the postulation of advanced states of maturity attained by the most or all adults but few adolescents. Many people continue to develop long beyond childhood, and their brains reflect those changes, but beyond age 12, there is no natural and universal state of maturity waiting to be achieved."

"Developmental changes beyond age 12 to 14 are much too stable and individualized, it appears to me, for a developmental panel, even if it included brain experts, to succeed in distinguishing age groups on the basis of their age development. Second, there is the reductionist fallacy. Brain data seem more scientific than behavioral data, but they are not, nor do they provide us with ultimate explanations, even if psychology can in principle be reduced to biology, a dubious proposition, we are a very long way from achieving such a reduction."

• Waber, D.P., et al. (2007). "The NIH MRI Study of Normal Brain Development: Performance of a Population Based Sample of Healthy Children Aged 6 to 18 Years on a Neuropsychological Battery," Journal of the International Neuropsychological Society, 13(5), 729-746.

  "Perhaps most intriguing are the age-related trajectories for raw score performance. For most tasks, proficiency improved dramatically between 6 and 10 years of age, leveling off during early adolescence (approximately 10 to 12 years of age), suggesting that for many neurocognitive tasks, children approach adult levels of performance at that age. For a few measures, scores increased linearly throughout the age range. These were tasks that assessed basic information processing, such as Coding, Digit Span, and Spatial Span. Still others were associated with a non-linear component during adolescence. Some showed a flattening of the curve followed by another period of acceleration, suggesting another spurt in mid-adolescence. Verbal learning actually reversed direction with performance declining in later adolescence."

• Adler, N.E., & Matthews, K. (1994). "Why do some people get sick and some stay well?," Annual Review of Psychology, 45, 229-259.

  "However, empirical tests show that adolescents are no less rational than adults. Applications of rational models to adolescent decision-making show that adolescents are consistent in their reasoning and behavior after the salient set of beliefs is assessed (Adler et al 1990). Quadrel et al (1993) demonstrated that adolescents are no more biased in their estimates of vulnerability to adverse health outcomes than are their parents."

• Weithorn, L. A. & Campbell, S. B. (1982). "The competency of children and adolescents to make informed treatment decisions," Child Development, 53(6), 1589-1598.

  "In general, minors aged fourteen were found to demonstrate a level of competence equivalent to that of adults. [...] The ages of eighteen or twenty-one as the "cutoffs" below which individuals are presumed to be incompetent to make determinations about their own welfare do not reflect the psychological capabilities of most adolescents."

• Offer, D. (1987). "In defense of adolescents," Journal of the American Medical Association, 257, 3407-3408.

  Mike Males describes this study: "Northwestern University psychiatrist Daniel Offer, the nation’s leading researcher on adolescents, studied 30,000 teenagers and adults from the 1960s to the 1990s. He and his colleagues found 85% to 90% of teens held attitudes and risk perceptions similar to that of their parents, were not alienated, did think about the future, were coping well with their lives, and did not display psychological disturbances. "Decision making for adults is no different than decision making among teenagers,” Offer reported in 1987 in the Journal of the American Medical Association."

• Offer, D., and Schonert Reichl, K.A. (1992). "Debunking the myths of adolescence: Findings from recent research," Journal of the American Academy of Child & Adolescent Psychiatry, 31, 1003 1014.

  "[T]he effects of pubertal hormones are neither potent nor pervasive (Brooks-Gunn and Reiter, 1990). [...] Adolescence does not occur in a vacuum and is significantly affected by the sociocultural context in which it occurs. A recent investigation by Enright et al. (1987) illustrates this point. This study was based on the careful reading of 89 articles in the Journal of Genetic Psychology for the past 100 years. The articles were rated for their conceptions about the nature of adolescence. Enright et al. demonstrated ideological bias in approaches to understanding adolescent psychology, specifically in relation to economic conditions. Specifically, in times of economic depression, theories emerged in the literature that portrayed adolescents as "immature, psychologically unstable, and in need of prolonged participation in the education system" (p. 553). In contrast, during wartime, the psychological competence of adolescents was accentuated. The authors point out, "The field of adolescent psychology is not free from the societal influences that impinge upon legislators, educators, and parents in shaping American adolescents" (p. 554)."

• Quadrel, M. J., Fischhoff, B., & Davis, W. (1993). "Adolescent (in)vulnerability," American Psychologist, 48, 102-116.

  "Three groups of subjects were asked to judge the probability that they and several target others (a friend, an acquaintance, a parent, a child) would experience various risks. Subjects were middle-class adults, their teenage children, and high-risk adolescents from treatment homes. All three groups saw themselves as facing somewhat less risk than the target others. However, this perception of relative invulnerability was no more pronounced for adolescents than for adults. Indeed, the parents were viewed as less vulnerable than their teenage children by both the adults and those teens. These results are consistent with others showing small differences in the cognitive decision-making processes of adolescents and adults. Underestimating teens' competence can mean misdiagnosing the sources of their risk behaviors, denying them deserved freedoms, and failing to provide needed assistance."

Risk Taking/Impulsivity/Prefrontal Physiology

The oft-repeated 25 year-old fallacy for the full maturation of the human brain is simplistic and outdated. If impulse control were dependent upon prefrontal volume, we would see no such thing as the quiet, studious preschooler - as all preschoolers have a tiny prefrontal cortex. As the previous studies suggest, the brains of teenagers are already losing gray matter and raw processing power is already declining by that age. Further studies are now informing us that functions of the prefrontal cortex are borrowed from other parts of the brain in teens, and raw levels of impulse-control are equal or greater. However, teenage boys in particular, might be slightly less discriminatory when facing tasks within a positive or negative emotional context. While this might manifest in poorer performance within an experimental context, it is likely to be an adaptive (possibly pro-reproductive) trait that is net beneficial to socialization/competence building during youth.

• Casey, B., (2013). "The Teenage Brain: Self Control," Current Directions in Psychological Science, Volume: 22 issue: 2, page(s): 82-87.

  Adolescence, by definition, involves new demands on the individual as she or he moves from dependence on the family unit to relative independence. This developmental period is not specific to humans, as evidenced by the increases in novelty seeking, interactions with peers, and fighting with parents observed in other species (see Romeo, 2013; Spear, 2013; both in this issue). These behaviors are thought to have evolved to serve adaptive functions related to successful mating and obtainment of resources necessary for survival (Spear & Varlinskaya, 2010). [...] To suggest that this period of development is one of no brakes or steering wheel (Bell & McBride, 2010) is to greatly oversimplify it. [...] Self-control—in this case, suppressing a compelling action—showed a different developmental pattern in the context of emotional information than in its absence, especially for males (Tottenham, Hare, & Casey, 2011). As illustrated in Figure 1 (also see Fig. 1 in Hare et al., 2008; National Research Council, 2011), when no emotional information is present, not only do many adolescents perform as well as adults, some perform even better. However, when decisions are required in the heat of the moment (i.e., in the presence of emotional cues; Fig. 2a), performance falters (Fig. 2b). Specifically, adolescents have difficulty suppressing a response to appetitive social cues relative to neutral ones. [...] Recently, a number of human imaging studies have attempted to evaluate this model and test for unique patterns of brain activity in adolescents during stereotypical risky behavior in the context of incentives (Chein, Albert, O’Brien, Uckert, & Steinberg, 2011; J. R. Cohen et al., 2010; Geier, Terwilliger, Teslovich, Velanova, & Luna, 2010; Van Leijenhorst et al., 2010). This work has challenged the view that diminished self-control in adolescents is due to a less mature prefrontal cortex that leads to less successful exertion of regulatory control on behavior (Bell & McBride, 2010). [...] Indeed, if the objective of adolescence is to gain independence from the family unit, then providing opportunities for adolescents to engage in new responsibilities is essential. Without opportunities and experiences to help optimally shape the adolescent’s brain and behavior, the objectives of this developmental phase will not easily be met."

• Romer, D. (2010). "Adolescent Risk Taking, Impulsivity, and Brain Development: Implications for Prevention," Developmental Psychobiology, 52(3): 263–276.

  "A review of the evidence for the hypothesis that limitations in brain development during adolescence restrict the ability to control impulsivity suggests that any such limitations are subtle at best. Instead, it is argued that lack of experience with novel adult behavior poses a much greater risk to adolescents than structural deficits in brain maturation [...] The evidence we have reviewed suggests that adolescent risk taking is not a universal phenomenon and that individual differences related to at least three types of impulsivity underlie such behavior in adolescents. Furthermore, at least two forms of impulsivity are associated with weak executive function as assessed by working memory and response inhibition tasks. However, sensation seeking does not appear to be inversely related to either of these executive functions and may actually be somewhat positively related to working memory ability."

• Moshman, David (2011). "Adolescent Rationality and Development: Cognition, Morality, and Identity, Third Edition.

  "There is no evidence that adolescents are uniquely egocentric or even much different from adults in this regard; on the contrary, research has shown age differences to be minimal or nonexistent (Millstein & Halpern-Felsher, 2002; Quadrel et al., 1993; Smetana & Villalobos, 2009). As fo the specific assertion that adolescents see themselves as invulnerable, it appears instead that adolescents routinely, and often drastically, overestimate their actual vulnerability (Millstein & Halpern-Felsher, 2002). [...] risk taking is not always bad, and adolescents are not uniquely prone to it. People of all ages take risks of all sorts, including foolish and dangerous risks; there is no empirical basis for the common assumption that risk taking is a special phenomenon of adolescence. On the contrary, direct comparisons of adolescents and adults show minimal age differences (Beyth-Marom et al., 1993). Sociological data indicate that when covariates such as poverty are controlled, adolescents are no more prone to risk taking than adults, who in fact take plenty of dubious risks (Males, 2009, 2010)."

Moral reasoning

• Haidt, J. (2001). "The emotional dog and its rational tail: A social intuitionist approach to moral judgment," Psychological Review, 108, 814-834.

  "Turiel (1983) has shown that young children do not believe [that actions are wrong just because they are punished]. They say that harmful acts, such as hitting and pulling hair, are wrong whether they are punished or not. They even say that such acts would be wrong if adults ordered them to be done."