Friday, October 19, 2007

First Article: Moffitt

Moffitt, T. E. (1993). Adolescence-limited and life-course-persistent antisocial behavior: A developmental taxonomy Psychological Review, 100 (4), 674-701

Remember: the article itself is on Blackboard! Check under "Course Materials -> Journal Club Articles."

Blogging on Peer-Reviewed ResearchOkay, this one's pretty hefty, but it's good. Terrie Moffitt develops her idea that there are two very distinct origins of criminal and delinquent behavior: one which is based on abnormal neurobiological pathology combined with exposure to environmental stressors, and one which is based on social adaptation. She argues that these two different origins manifest in very different behavior patterns, affecting the nature of the antisocial behavior, the persistence of the behavior over the life course, and the purpose of the behavior.

Echoing what Dr. Geiselman said in class, most crimes are committed by (male) offenders between the ages of 12 and 25 (note the dramatic spike in the graph on the second page). Furthermore, the number of crimes is fueled by a dramatic increase in the number of offenders, not just in the number of crimes each offender performs. Yet around age 18, this increase stops. For all practical purposes, no one starts a life of crime after the age of 18, unless there are extreme circumstances, such as losing a job and house.

So there's a steady increase in the incidence of antisocial behavior (as well as crimes) starting in early adolescence, and a tapering off in late adolescence. But this does not affect everyone equally: there seems to be about 5% of men, found in samples across the globe, who continue to offend into their 30s, their 40s, their 50s, as long as they are capable of it. What's more, it seems that they start earlier, too. They're the ones who are likely to be guilty of torturing cats or setting fires at 7, and then battering spouses and driving drunk at 40. Is there something fundamentally different between these offenders and everyone else?

Moffitt argues that there is. Her hypothesis is that this 5% have certain risk factors that, when expressed in the wrong environments, lead to stable and persistent patterns of antisocial behavior. Brain insults, whether genetic, prenatal, or postnatal; poor parenting, sometimes compounded by generational patterns of neglect or abuse; the nature of the reactions to a child's early antisocial behaviors; environments that maintain, reinforce, and strengthen negative behavior patterns. Dr. Geiselman mentioned the highly heritable nature of criminality: adopted children will generally resemble their biological parents more than their adoptive parents in terms of antisocial behaviors. There are many mechanisms by which this might occur - there is no single "antisociality gene" - but factors such as low arousal levels and difficult temperaments can set up interactions with caregivers and the environment that amplify inherent tendencies. Just because someone is raised in a different environment does not mean that they won't encounter the same reactions and biases.

On the other hand, there are also, Moffitt argues, people who only display antisocial behavior over a limited time period, namely adolescence. And it's a lot of people: Moffitt says 1/3 are arrested over their lifetimes for serious offenses, Geiselman said about 50% have been imprisoned at some time. In adolescence, it seems that antisocial behavior is more the norm than the exception. So are all these people psychopaths? Most go on to have clean records after they become adults, so it can't be some natural criminal disposition. Instead, this type of antisociality seems to rely on a number of factors.

  • Developmentally, their frontal lobes are still maturing. The frontal lobe is responsible for much of the voluntary control we have over our behavior. Whenever we have to plan something or weigh the consequences of an action we rely on our frontal lobes. Phineas Gage, the classic frontal lobe example, was a reliable, productive railway worker until he got a steel bar driven through his eye socket and out the top of his head. While he miraculously survived, it destroyed much of his frontal lobe, after which he started gambling, abusing his girlfriend, mouthing off, and showing up late to work. It's remarkable what a faulty frontal lobe can do.
  • Biologically, they're getting bombarded by hormones such as testosterone, which, while it may not be directly linked to criminality, has associations with aggression, emotion perception, and sex drive. Plus, they're also simply getting bigger, with all that that entails: they can beat up more people, break into houses, drive, etc.
  • Socially, they're learning new behaviors. Adolescents have access to a world of new stimuli: drugs, sex, violence. They may have seen these on TV before, but now they're at a point where it becomes possible to actually try them out. These types of behaviors are often reinforced by peers, which means that there's even more of an incentive to try them.
  • Culturally, they're increasingly adrift. Figure 4 shows that there has been similar trends in age and criminal behavior over the years, but after the industrial period of the early 20th century, the level of adolescent crime has increased steadily. Moffitt attributes this to the growing gulf between childhood and adulthood that adolescents become trapped in: too old for this, not old enough for that. Adolescents are now in school longer and delay marriage more than in the past, but at the same time they're sexually maturing earlier. If they want to assume adult roles, they sometimes have to force them by challenging adult rules. It's at this point that the persistent adolescents, the ones who have been getting in trouble for years already, become a major influence as the "cool kids," but cruelly they're soon passed on as being weird and dangerous.
When antisocial behaviors are instrumental and influenced by biological and social changes that have the likelihood of stabilizing, it's easy for them to be outgrown. After a person gets a regular job and turns 21, he doesn't have to steal alcohol with his friends. This shift in motivation is what accounts for the rapid decline in offending behavior.

There are some problems with and alternatives to Moffitt's theory, which she touches on at the end. For example, Zimbardo has suggested that, given the right environmental conditions, anyone can be turned to criminal acts; fortunately, anyone can be influenced to perform heroic acts, as well. We'll go more into his research later, but for now, let's open it up: what do you think? Is this proveable? Is it useful? Does it really change anything if it were true? Are there alternate explanations for what she's found, considering there are no actual experiments in this study?

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