Avshalom Caspi

Developmental Psychobiology of Aggression: Life-Course Persistent and Adolescence-Limited Antisocial Males: Longitudinal Followup to Adulthood

This chapter tests and refines a developmental taxonomy of antisocial behavior, which proposed two primary hypothetical prototypes: life-course persistent offenders whose antisocial behavior begins in childhood and continues worsening thereafter, versus adolescence-limited offenders whose antisocial behavior begins in adolescence and desists in young adulthood (Moffitt, 1993). Two of our previous reports have described clinically defined groups of childhood-onset and adolescence-onset antisocial youths in the Dunedin birth cohort during childhood (Moffitt & Caspi, 2001) and at age 18 (Moffitt, Caspi, Dickson, Silva, & Stanton, 1996). Recently we followed up the cohort at age 26, and here we describe how the two groups of males fared in adulthood. In so doing we test a hypothesis critical to the theory : that childhood-onset, but not adolescent-onset, antisocial behavior is associated in adulthood with antisocial personality, violence, and continued serious antisocial behavior that expands into maladjustment in work life and victimization of partners and children (Moffitt, 1993). THE TWO PROTOTYPES AND THEIR PREDICTED ADULT OUTCOMES According to the theory, life-course persistent antisocials are few, persistent, and pathological. Adolescence-limited antisocials are common, relatively temporary, and near normative. The developmental typology hypothesized that childhood-onset versus adolescent-onset conduct problems have different etiologies. In addition, the typology differed from other developmental crime theories by predicting different outcome pathways for the two types across the adult life-course (Caspi & Moffitt, 1995; Moffitt, 1993, 1994, 1997).

Sex Differences in Antisocial Behaviour: Sex differences in the amount of antisocial behaviour: dimensional measures

Do males and females differ in their antisocial behaviour? This question has been addressed by developmental psychologists, social psychologists, psychiatrists, and criminologists. The answers provided are not always exactly the same for several reasons. First, different disciplines measure different behaviours that may or may not measure the same latent variable. For example, whereas child psychologists often focus on behaviours in situ such as rough-and-tumble play, criminologists tend to index antisocial behaviour through official records of conviction for crime. Second, different disciplines focus on antisocial behaviour at different points in the life span. Developmental researchers tend to focus on the early years of life, psychiatrists focus on adolescents, social psychologists focus on college students in their late teens and early twenties, and criminologists focus on older juveniles and adults. Third, different disciplines often rely on different methods to measure antisocial behaviour. For example, developmentalists often rely on observational methods, social psychologists rely on standardized experimental paradigms to elicit analogue responses, psychiatrists use diagnostic data gathered via parental and self-reports, and criminologists favor still different types of data, such as self-report interviews and police and court records. These methodological factors tend to covary within discipline. For example, observational studies of naturalistic behaviours are primarily restricted to younger populations, whereas criminological studies of court records are generally restricted to older populations.

Sex Differences in Antisocial Behaviour: Do girls who develop antisocial behaviour surmount a higher threshold of risk than their male counterparts?

For a long time, many researchers have been attracted to the hypothesis that females who develop antisocial behaviour surmount a higher threshold of risk than males and are therefore more severely afflicted. This hypothesis goes by many names, including group resistence, the threshold effect, and the gender paradox. Because the hypothesis holds such wide appeal, it is worth revisiting the logic behind it. The hypothesis is built on the factual observation that fewer females than males act antisocially. Because this is true, then the deduction is made that some factor has raised the threshold that females must pass before they convert antisocial attitudes, feelings, or motives into actual antisocial actions. A higher threshold implies that the few females who have indeed passed their high threshold were pushed over it by stronger causes than were the males who passed their low threshold. Generally the female threshold is presumed to be raised by gender-role socialization of females against aggression, at the level of the culture. The push over the threshold is presumed to come from psycho-biological or developmental factors, at the level of the individual. The hypothesis is typically addressed empirically by comparing the strength of aetiological variables across groups of antisocial females and males, looking for evidence of more severe aetiology among females. If more severe aetiology is found for girls, then the inference is made that a higher threshold for girls exists. The criminologist Thorsten Sellin (1938) referred to this line of reasoning as the ‘group resistence’ hypothesis.