¡Descarga Understanding Adolescent Development: A Neuroscientific Perspective - Prof. Sánchez Jiméne y más Apuntes en PDF de Psicología solo en Docsity!
Cognitive and affective development
in adolescence
Laurence Steinberg
Department of Psychology, Temple University, Philadelphia, PA 19122, USA
Questions about the nature of normative and atypical development in adolescence have taken on special significance in the last few years, as scientists have begun to recast old portraits of adolescent behavior in the light of new knowledge about brain development. Adolescence is often a period of especially heightened vulnerability as a consequence of potential disjunctions between developing brain, behavioral and cognitive systems that mature along different timetables and under the control of both common and independent biological processes. Taken together, these develop- ments reinforce the emerging understanding of adoles- cence as a critical or sensitive period for a reorganization of regulatory systems, a reorganization that is fraught with both risks and opportunities.
Introduction Adolescence is characterized by an increased need to regulate affect and behavior in accordance with long-term goals and consequences, often at a distance from the adults who provided regulatory structure and guidance during childhood. Because developing brain, behavioral and cognitive systems mature at different rates and under the control of both common and independent biological processes, this period is often one of increased vulner- ability and adjustment. Accordingly, normative develop- ment in adolescence can profitably be understood with respect to the coordination of emotional, intellectual and behavioral proclivities and capabilities, and psychopathol- ogy in adolescence may be reflective of difficulties in this coordination process. The notion that adolescence is a heightened period of vulnerability specifically because of gaps between emotion, cognition and behavior has important impli- cations for our understanding of many aspects of both normative and atypical development during this period of the life-span. With respect to normative development, for instance, this framework is helpful in understanding age differences in judgment and decision-making, in risk- taking, and in sensation-seeking [1]. With respect to atypical development, the framework helps us to under- stand why adolescence can be a time of increased risk for the onset of a wide range of emotional and behavioral problems, including depression, violent delinquency and substance abuse [2].
Questions about the nature of normative and atypical development in adolescence have taken on special signifi- cance in the last few years as scientists have begun to recast old portraits of adolescent psychological develop- ment in light of new knowledge about adolescent brain development. Recent discoveries in the area of develop- mental neuroscience have stimulated widespread scien- tific and popular interest in the study of brain development during adolescence, as well as substantial speculation about the connections between brain matu- ration and adolescents’ behavioral and emotional devel- opment. Indeed, the topic has garnered such widespread public interest that it was the subject of a recent cover story in Time magazine aimed at parents of teenagers [3], and was raised in arguments submitted in late 2004 to the United States Supreme Court in connection with the Court’s consideration of the constitutionality of the juvenile death penalty [4].
Brain development in adolescence As reviewed in the accompanying article by Paus [5] there is growing evidence that maturational brain processes are continuing well through adolescence. Even relatively simple structural measures, such as the ratio of white- to-gray matter in the brain, demonstrate large-scale changes into the late teen-age years [6–8]. The impact of this continued maturation on emotional, intellectual and behavioral development has yet to be thoroughly studied, but there is considerable evidence that the second decade of life is a period of great activity with respect to changes in brain structure and function, especially in regions and systems associated with response inhibition, the cali- bration of risk and reward, and emotion regulation. Contrary to earlier beliefs about brain maturation in adolescence, this activity is not limited to the early adolescent period, nor is it invariably linked to processes of pubertal maturation (Figure 1). Two particular observations about brain development in adolescence are especially pertinent to our under- standing of psychological development during this period. First, much brain development during adolescence is in the particular brain regions and systems that are key to the regulation of behavior and emotion and to the perception and evaluation of risk and reward. Second, it appears that changes in arousal and motivation brought on by pubertal maturation precede the development of regulatory competence in a manner that creates a disjunction between the adolescent’s affective experience
Corresponding author: Steinberg, L. ([email protected]). Available online 23 December 2004
www.sciencedirect.com 1364-6613/$ - see front matter Q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.tics.2004.12.
and his or her ability to regulate arousal and motivation. To the extent that the changes in arousal and motivation precede the development of regulatory competence – a reasonable speculation, but one that has yet to be confirmed – the developments of early adolescence may well create a situation in which one is starting an engine without yet having a skilled driver behind the wheel [9].
Cognitive development in adolescence Until recently, much of the work on adolescent cognitive development was devoted to a search for a core mechanism that could account parsimoniously for broad changes in adolescent thinking [10]. After nearly 50 years of search- ing, what has emerged instead is the necessity of an integrated account. What lies at the core of adolescent cognitive development is the attainment of a more fully conscious, self-directed and self-regulating mind [10]. This is achieved principally through the assembly of an advanced ‘executive suite’ of capabilities [11], rather than through specific advancement in any one of the constituent elements. This represents a major shift in prevailing views of adolescent cognition, going beyond the search for underlying elements [12] that are formed and operate largely outside awareness. As Keating [10] has noted, the plausibility of such an integrative account has been substantially enhanced by recent major advances in the neurosciences [6–8,13–18], in comparative neuroanatomy across closely related primate species that illuminate core issues of human cognitive evolution [10,19], and in a deepened under- standing of the critical role of culture and context in the shaping of cognitive and brain development [11,20]. Much of the underlying action is focused on specific develop- ments in the prefrontal cortex, but with an equally significant role for rapidly expanding linkages to the whole brain [11,15,21]. This complex process of assembly is supported by increasingly rapid connectivity (through continued myelination of nerve fibers), par- ticularly in communication among different brain regions, and by significant and localized synaptic pruning, especially in frontal areas that are crucial to executive functioning [6–8,18].
Whatever the underlying processes, during early adolescence, individuals show marked improvements in reasoning (especially deductive reasoning), information processing (in both efficiency and capacity), and expertise. These conclusions derive from studies of age differences in logical reasoning on tasks in which participants are asked to solve verbal analogies or analyze logical propositions; basic cognitive processes, such short- or long-term memory; and in specialized knowledge [10]. There has been broad consensus for more than 25 years that, as a result of these gains, individuals become more capable of abstract, multidimensional, planned and hypothetical thinking as they develop from late childhood into middle adolescence (less is known about cognitive changes during late adolescence). No research in the past several decades has challenge this conclusion.
Implications of new brain maturation research for adolescent cognitive development After a rather lengthy period during the late 1980s and early 1990s, when the study of adolescent cognitive development was more or less moribund, interest in intellectual development during adolescence has been revitalized in recent years in two ways. First, researchers in the field of developmental neuroscience began to direct attention to the study of structural and functional aspects of brain development during early adolescence [6,8,13,22]. These studies have pointed both to significant growth and significant change in multiple regions of the prefrontal cortex throughout the course of adolescence, especially with respect to processes of myelination and synaptic pruning (both of which increase the efficiency of infor- mation processing) [8,17,23]. These changes are believed to undergird improvements in various aspects of executive functioning, including long-term planning, metacognition, self-evaluation, self-regulation and the coordination of affect and cognition [10]. Most research has focused on age differences in skills known to be related to functioning in the dorsolateral region of the prefrontal cortex, such as those involving working memory, spatial working memory and planning [24–26], but two recent studies [27,28] indicate as well that adolescence is a time of improvement
Puberty heightens emotional arousability, sensation-seeking, reward orientation
Period of heightened vulnerability to risk-taking and problems in regulation of affect and behavior
Maturation of frontal lobes facilitates regulatory competence
Early adolescence Middle adolescence Late adolescence
TRENDS in Cognitive Sciences
Figure 1. It has been speculated that the impact of puberty on arousal and motivation occurs before the maturation of the frontal lobes is complete. This gap may create a period of heightened vulnerability to problems in the regulation of affect and behavior, which might help to explain the increased potential in adolescence for risk-taking, recklessness, and the onset of emotional and behavioral problems.
of adolescence, their reasoning about real-life problems is often not as advanced as their reasoning about hypothe- tical dilemmas [42]. The correlation between adolescents’ moral reasoning and their moral behavior is especially likely to break down when individuals define issues as personal choices rather than ethical dilemmas (for instance, when using drugs is seen as a personal matter rather than a moral issue) [43]. Similarly, when faced with a logical argument, adolescents are more likely to accept faulty reasoning or shaky evidence when they agree with the substance of the argument than when they do not [44,45]. And, although individuals’ ability to look at things from another person’s perspective increases in adoles- cence, the extent to which this advanced social perspective taking translates into tolerance for others’ viewpoints depends on the particular issue involved [46]. In other words, adolescents’ social reasoning, like that of adults, is influenced not only by their basic intellectual abilities, but by their desires, motives and interests.
Affect and cognition In contrast to most measures of cognitive development in adolescence, which seem to correlate more closely with age and experience rather than the timing of pubertal maturation, there is evidence for a specific link between pubertal maturation and developmental changes in arousal, motivation and emotion. For example, there is evidence that pubertal development directly influences the development of romantic interest and sexual motiv- ation [47,48]. There is also evidence that some changes in emotional intensity and reactivity, such as changes in the frequency and intensity of parent-adolescent conflict, may be more closely linked to pubertal maturation than to age [49]. Some cognitive skills related to human face-proces- sing have also shown intriguing alterations in mid- adolescence – an apparent decrement in face processing skills that is associated with sexual maturation (measured by Tanner staging by physical examinations) rather than
with age or grade level [50]. A parallel finding has been reported for voice recognition [51]. There is also evidence that increases in sensation- seeking, risk-taking and reckless behavior in adolescence are influenced by puberty and not chronological age. For example, in a study by Martin et al. [29], where sensation- seeking and risk behaviors were examined in a large group of young adolescents aged 11 to 14, there was no significant correlation between age and sensation-seeking, but a significant correlation between sensation-seeking and pub- ertal stage. There is also evidence in animal and human studies supporting a link between increasing levels of reproductive hormones and sensitivity to social status [52,53], which is consistent with the link between puberty and risk-taking, since several influential theories of adoles- cent risk-taking [54] suggest that at least some of this behavior is done in the service of enhancing one’s standing with peers. Although further research is much needed, it appears that there are important links between pubertal maturation and social information-processing. In some models of the development of affect regulation there is an explicit emphasis on cognitive systems exerting control over emotions and emotion-related behavior [55]. Many aspects of affect regulation involve the ability to inhibit, delay or modify an emotion or its expression in accordance with some rules, goals or strategies, or to avoid learned negative consequences. However, there is increas- ing understanding that cognitive-emotional interactions in adolescence also unfold in the other direction in important ways. Thus, just as cognition has an important impact on emotion, emotion has an important impact on basic cognitive processes, including decision-making and behavioral choice.
Decision-making and risk-taking Behavioral data have often made it appear that adoles- cents are poor decision-makers (i.e. their high-rates of participation in dangerous activities, automobile acci- dents, drug use and unprotected sex). This led initially to hypotheses that adolescents had poor cognitive skills relevant to decision-making or that information about consequences of risky behavior may have been unclear to them [56,57]. In contrast to those accounts, however, there is substantial evidence that adolescents engage in dangerous activities despite knowing and understanding the risks involved [29,58,59,60–63]. Thus, in real-life situations, adolescents do not simply rationally weigh the relative risks and consequences of their behavior – their actions are largely influenced by feelings and social influences [1]. In contrast to much previous work on adolescent decision-making that emphasized cognitive processes and mainly ignored affective ones, there is now increasing recognition of the importance of emotion in decision- making [64]. The ‘decision’ to engage in a specific behavior with long-term health consequences – such as smoking a cigarette, drinking alcohol, or engaging in unprotected sex
- cannot be completely understood within the framework of ‘cold’ cognitive processes. (‘Cold’ cognition refers to thinking processes under conditions of low emotion and/or arousal whereas ‘hot’ cognition refers to thinking under conditions of strong feelings or high arousal and which
Alone With friends
Adolescents Youths Adults
Number of risky restarts
TRENDS in Cognitive Sciences
Figure 2. In a study designed to investigate age differences in risk-taking [37], participants were asked to play a computerized game in which they had opportunities to take driving risks, such as continuing to drive after a traffic light had turned yellow in order to drive the car further and earn more points. Individuals were randomly assigned to one of two conditions: playing the game alone, or playing it while two friends were watching and giving advice. The graph shows the number of times individuals risked crashing the car by stopping and then restarting it to try to drive a bit further after the yellow light had appeared. Adolescents (aged 13–16), youths (aged 18–22), and adults (aged 24 and older) demonstrated equivalent degrees of risk-taking when alone, but in the presence of peers, adolescents and youths, but not adults, took more risks.
therefore may be much more important to understanding risky choices in real-life situations.) These affective influences are relevant in many day-to-day ‘decisions’ that are made at the level of ‘gut-feelings’ regarding what to do in a particular situation (rather than deliberate thoughts about outcome probabilities or risk value). These ‘gut feelings’ appear to be the products of affective systems in the brain that are performing computations that are largely outside conscious awareness [65,66]. How these feelings develop, become calibrated during maturation, and are influenced by particular types of experiences at particular points in development are only beginning to be studied within the framework of affective neuroscience [29]. It does, however, appear that puberty and sexual maturation have important influences on at least some aspects of affective influences on behavior through new drives, motivations and intensity of feelings, as well as new experiences that evoke strong feelings (such as developing romantic involvement) [67,68].
The development of regulatory competence During the adolescent transition, regulatory systems are gradually brought under the control of central executive functions, with a special focus on the interface of cognition and emotion. Two important observations are especially important. The first is that the development of an integrated and consciously controlled ‘executive suite’ of regulatory capacities is a lengthy process. Yet, adolescents confront major, emotionally laden life dilemmas from a relatively early age – an age that has become progressively younger over historic time due to the decline in the age of pubertal onset and in the age at which a wide range of choices are thrust upon young people, as well as a decline in the active monitoring of adolescents by parents as a result of changes in family composition and labor force participation. The second observation is that the acquisition of a fully coordinated and controlled set of executive functions occurs relatively later in development [10]. As such, it is less likely to be canalized (to the same degree as, say, early language acquisition), leaving greater opportunities for suboptimal trajectories. These suboptimal patterns of development take many different forms, clusters of which are associated with broad categories of psycho- pathology, such as the excessive down-regulation of mood and motivation that characterizes many internalizing difficulties, or the inadequate control of arousal that is associated with a wide range of risky behaviors typically seen as externalizing problems.
Concluding comments Like early childhood, adolescence may well be a sensitive or critical developmental period for both normative and maladaptive patterns of development [69–71]. Several aspects of development during this period are especially significant in this regard, among them: the role of puberty in a fundamental restructuring of many body systems and as an influence on social information-processing; the apparent concentration of changes in the adolescent brain in the prefrontal cortex (which serves as a governor of cognition and action) together with the enhanced inter- regional communication between the prefrontal cortex
and other brain regions; and the evidence for substantial synaptic pruning and for non-trivial physiological rever- sibility of behavioral and neuroendocrine patterns arising from early developmental experiences. Taken together, these developments reinforce the emerging understand- ing of adolescence as a critical or sensitive period for a reorganization of regulatory systems, a reorganization that is fraught with both risks and opportunities [10]. As we look to the future of research on cognitive and affective development in adolescence, the challenge facing researchers will be integrating research on psychological, neuropsychological and neurobiological development. What we now have are interesting pieces of a complicated puzzle, but the pieces have yet to be fit together in a way that moves the field out of the realm of speculation and towards some measure of certainty.
Acknowledgements Many of the ideas expressed in this article grew out of the work of the MacArthur Foundation Research Network on Psychopathology and Development. I am especially grateful to Ron Dahl, Dan Keating, David Kupfer, Ann Masten and Danny Pine for their contributions to the enterprise. Thanks also to Marnia Davis for bibliographic assistance.
References 1 Steinberg, L. (2004) Risk-taking in adolescence: What changes, and why? Ann. N. Y. Acad. Sci. 1021, 51– 2 Steinberg, L. et al. Psychopathology in adolescence: Integrating affective neuroscience with the study of context. In Developmental Psychopathology Vol. 1: Theory and Method (Cicchetti, D. and Cohen, D., eds), Wiley (in press) 3 Wallis, C. (2004) What makes teens tick. Time 10 May, pp. 56– 4 Wiener, R. and Miller, M. (2004) Determining the death penalty for juveniles. APA Monitor on Psychology 35, 68 5 Paus, T. (2005) Mapping brain maturation and cognitive development during adolescence. Trends Cogn. Sci. 9, 000– 6 Giedd, J. et al. (1999) Brain development during childhood and adolescence: A longitudinal MRI study. Nat. Neurosci. 2, 861– 7 Sowell, E.R. et al. (2001) Improved memory functioning and frontal lobe maturation between childhood and adolescence: A structural MRI study. J. Int. Neuropsychol. Soc. 7, 312– 8 Sowell, E.R. et al. (2002) Development of cortical and subcortical brain structures in childhood and adolescence: A structural MRI study. Dev. Med. Child Neurol. 44, 4– 9 Dahl, R.E. (2001) Affect regulation, brain development, and behavior- al/emotional health in adolescence. CNS Spectr. 6, 1– 10 Keating, D.P. (2004) Cognitive and brain development. In Handbook of Adolescent Psychology (2nd edn) (Lerner, R.J. and Steinberg, L.D., eds), pp. 45–84, Wiley 11 Donald, M. (2001) A Mind So Rare: The Evolution of Human Consciousness, Norton 12 Dennett, D.C. (1996) Kinds of Minds: Toward an Understanding of Consciousness, Basic Books 13 Casey, B.J. et al. (2000) Structural and functional brain development and its relation to cognitive development. Biol. Psychol. 54, 241– 14 Johnson, M.H. (2001) Functional brain development in humans. Nat. Rev. Neurosci. 2, 475– 15 Luna, B. et al. (2001) Maturation of widely distributed brain function subserves cognitive development. Neuroimage 13, 786– 16 Nelson, C.A. (1999) Neural plasticity and human development. Curr. Dir. Psychol. Sci. 8, 42– 17 Paus, T. et al. (1999) Structural maturation of neural pathways in children and adolescents: in vivo study. Science 283, 1908– 18 Steingard, R.J. et al. (2002) Smaller frontal lobe white matter volumes in depressed adolescents. Biol. Psychiatry 52, 413– 19 Rilling, J.K. and Insel, T.R. (1999) The primate neocortex in comparative perspective using magnetic resonance imaging. J. Hum. Evol. 37, 191–
