Developmental & Life-Course Theories Notes

Objective: To understand the patterns of criminal behavior over time.
Research Findings:
- Crime Peaks in Adolescence: Criminal activity is observed to peak during adolescence and declines as individuals age (Blumstein et al., 1986; Farrington et al., 2013).
- Consistent Behavior: Some individuals exhibit a consistent level of criminal or conforming behavior throughout their lives.
- Variable Criminality: Others show variability in criminal behavior as they age (Laub & Sampson, 2003; Sampson & Laub, 1993).

Age-Crime Curve: Shows an increase in crime rates during early adolescence, peaking in mid to late teenage years, and decreasing through early adulthood (Farrington, 1986).
- Emerging Adults: Defined as individuals aged 18 to 25 (Arnett, 2000).
- Critiques of Age-Crime Distribution:
- Misapplications may arise from advocating longitudinal studies over cheaper cross-sectional studies (Hirschi & Gottfredson, 1983).
- Age-crime curve may reflect changes in opportunity rather than changes in criminal propensity (Gottfredson & Hirschi, 1990).

Research Basis: Informed by early life-history and longitudinal data (Shaw, 1930; Glueck & Glueck, 1950; Wolfgang et al., 1972).
Key Factors in Criminal Careers:
- Onset: Initiation of criminal activity.
- Continuity: Persistence and escalation of criminal activity.
- Change: Can involve desistance or termination of criminal activity.
- Five Dimensions:
1. Prevalence: Number of individuals involved at any level.
2. Frequency: Number of offenses committed by active offenders.
3. Age of Onset: Age at which the first crime is committed.
4. Age of Desistance: Age at last crime committed.
5. Criminal Career Length: Calculated as age of desistance minus age of onset.

Prevalence Statistics:
- By age 30, up to 96% of self-reported criminal involvement and 40% in official records (Farrington, 2002).
Crime Frequency: Peaks at age 16 for self-reports and ages 17-20 for convictions, followed by a decline (Piquero et al., 2003).
Age of Onset: Peaks for minor crimes at ages 13-14 and for serious crimes at ages 17-19 (Farrington, 1990).
Desistance: Average age of last crime ranges from 20-29 years (Farrington, 1992).
Career Length:
- Average of 10.4 years from first to last conviction (Farrington, 1992).
- Includes one-time offenders averages 7.1 years.
- For all crimes, the average is 25.6 years (Laub & Sampson, 2003).

Background: Schmidt-Nielsen Professor at Duke University and King's College London.
Contributions: Noted for work identifying patterns of criminality at different developmental stages.

Moffitt's Proposition: Two distinct groups of offenders:
- Adolescence-Limited (AL):
- Engage in delinquency during adolescence, cease as they transition to adulthood.
- Motivated by social factors and maturity gaps.
- Life-Course Persistent (LCP):
- Develop conduct disorders early in life, continuing criminality into adulthood.
- Associated biological and psychological deficits leading to chronic behavior.

Characteristics:
- Small percentage of total youth; their deviance has biological roots linked to neuropsychological deficits.
- These deficits can result in lower verbal ability and executive functioning, leading to a higher likelihood of antisocial conduct.

Characteristics:
- Represent the majority of youth delinquents.
- Rebellion linked to a maturity gap; no significant deficits compared to LCPs.
- Tend to conform to social norms as they mature, leading to natural desistance from criminal behavior.
- Processes of Social Mimicry: AL youth often imitate behaviors from LCP youth, leading to initial delinquency but eventually adhere to societal norms as they age.

Significant support for the distinctions between AL and LCP groups, including various subgroups like chronic and sporadic offenders.